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[[Category:Boot loaders (English)]]
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[[Category:Boot loaders]]
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{{i18n|GRUB2}}
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[[cs:GRUB2]]
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[[de:GRUB]]
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[[es:GRUB2]]
 
[[fr:GRUB2]]
 
[[fr:GRUB2]]
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[[id:GRUB2]]
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[[it:GRUB2]]
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[[ru:GRUB2]]
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[[tr:GRUB2]]
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[[zh-CN:GRUB2]]
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[[zh-TW:GRUB2]]
 
{{Article summary start}}
 
{{Article summary start}}
 
{{Article summary text|Covers various aspects of the next generation of the GRand Unified Bootloader (GRUB2).}}
 
{{Article summary text|Covers various aspects of the next generation of the GRand Unified Bootloader (GRUB2).}}
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{{Article summary text|{{Boot process overview}}}}
 
{{Article summary text|{{Boot process overview}}}}
 
{{Article summary heading|Related}}
 
{{Article summary heading|Related}}
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{{Article summary wiki|Burg}} - Burg is a brand-new boot loader based on GRUB2. It uses a new object format which allows it to be built in a wider range of OS, including Linux/Windows/OSX/Solaris/FreeBSD, etc. It also has a highly configurable menu system which works in both text and graphic mode.  
+
{{Article summary wiki|BURG}} - BURG is a brand-new boot loader based on GRUB2. It can be built on a wider range of OS, and has a highly configurable menu system which works in both text and graphic mode.
 +
{{Article summary wiki|GRUB Legacy}} - previous Version, now obsolete.
 
{{Article summary heading|Resources}}
 
{{Article summary heading|Resources}}
−
{{Article summary link|GNU GRUB -- GNU Project|http://www.gnu.org/software/grub/}}
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{{Article summary wiki|GRUB EFI Examples}}
 +
{{Article summary link|GNU GRUB - GNU Project|https://www.gnu.org/software/grub/}}
 
{{Article summary end}}
 
{{Article summary end}}
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+
[https://www.gnu.org/software/grub/ GRUB2] is the next generation of the GRand Unified Bootloader (GRUB). GRUB2 is derived from [http://www.nongnu.org/pupa/ PUPA] which was a research project to investigate the next generation of GRUB. GRUB2 has been rewritten from scratch to clean up everything and provide modularity and portability [https://www.gnu.org/software/grub/grub-faq.html#q1].
−
[http://www.gnu.org/software/grub/ GRUB2] is the next generation of the GRand Unified Bootloader (GRUB). GRUB2 is derived from [http://www.nongnu.org/pupa/ PUPA] which was a research project to investigate the next generation of GRUB. GRUB 2 has been rewritten from scratch to clean up everything and provide modularity and portability [http://www.gnu.org/software/grub/grub-faq.en.html#q1].
 
  
 
In brief, the ''bootloader'' is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the Linux kernel. The kernel, in turn, initializes the rest of the operating system.
 
In brief, the ''bootloader'' is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the Linux kernel. The kernel, in turn, initializes the rest of the operating system.
  
 
== Preface ==
 
== Preface ==
 +
Here is some information that needs to be clarified:
 +
* The name ''GRUB'' officially refers to version ''2'' of the software, see [https://www.gnu.org/software/grub/]. If you are looking for the article on the legacy version, see [[GRUB Legacy]].
  
−
Although, [[GRUB]] (i.e. version 0.9x) is the de facto standard bootloader of Linux, it is considered 'legacy' by upstream. It is being replaced by GRUB2 in many distributions. Upstream recommends GRUB2 >=1.99~rc2 over grub-legacy, even for current grub-legacy users.
+
* From 1.99-6 onwards, GRUB2 supports [[Btrfs]] as root (without a separate {{ic|/boot}} filesystem) compressed with either zlib or LZO.
  
−
{{Note|grub2 from 1.99~rc2 and later supports btrfs as root (without a separate /boot filesystem).}}
+
* For GRUB2 UEFI info, it is recommended to read the [[Unified Extensible Firmware Interface|UEFI]], [[GUID Partition Table|GPT]] and [[UEFI Bootloaders]] pages before reading this page.
  
 
=== Notes for current GRUB Legacy users ===
 
=== Notes for current GRUB Legacy users ===
 +
* Upgrade from [[GRUB Legacy]] to GRUB2 is the much same as fresh installing GRUB2 which is covered [[#Installation|below]].
  
−
* There are differences in the commands of GRUB and GRUB2. Familiarize yourself with [http://www.gnu.org/software/grub/manual/grub.html#Commands GRUB2 commands] before proceeding (e.g. "find" has been replaced with "search").
+
* There are differences in the commands of GRUB and GRUB2. Familiarize yourself with [https://www.gnu.org/software/grub/manual/grub.html#Commands GRUB2 commands] before proceeding (e.g. "find" has been replaced with "search").
  
 
* GRUB2 is now ''modular'' and no longer requires "stage 1.5". As a result, the bootloader itself is limited -- modules are loaded from the hard drive as needed to expand functionality (e.g. for [[LVM]] or RAID support).
 
* GRUB2 is now ''modular'' and no longer requires "stage 1.5". As a result, the bootloader itself is limited -- modules are loaded from the hard drive as needed to expand functionality (e.g. for [[LVM]] or RAID support).
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==== BIOS systems ====
 
==== BIOS systems ====
  
−
===== [[GPT]] specific instructions =====
+
===== [[GUID Partition Table]] (GPT) specific instructions =====
−
 
+
GRUB2 in BIOS-GPT configuration requires a [http://www.gnu.org/software/grub/manual/html_node/BIOS-installation.html BIOS Boot Partition] to embed its {{ic|core.img}} in the absence of post-MBR gap in GPT partitioned systems (which is taken over by the GPT Primary Header and Primary Partition table). This partition is used by GRUB2 only in BIOS-GPT setups. No such partition type exists in case of MBR partitioning (at least not for GRUB2). This partition is also not required if the system is UEFI based, as no embedding of bootsectors takes place in that case. Syslinux does not require this partition.
−
GRUB2 in BIOS-GPT configuration requires a BIOS Boot Partition to embed its core.img in the absence of post-MBR gap in GPT partitioned systems (which is taken over by the GPT Primary Header and Primary Partition table). This partition is used by GRUB2 only in BIOS-GPT setups. No such partition type exists in case of MBR partitioning (at least not for GRUB2). This partition is also not required if the system is UEFI based, as no embedding of bootsectors takes place in that case. Syslinux does not require this partition.
 
−
 
 
−
For a BIOS-GPT configuration, create a 2 MiB partition using cgdisk or GNU Parted with no filesystem. The location of the partition in the partition table does not matter but it should be within the first 2 TiB region of the disk. It is advisable to put it somewhere in the beginning of the disk before the /boot partition. Set the partition type to "EF02" in cgdisk or {{ic|set <BOOT_PART_NUM> bios_grub on}} in GNU Parted.
 
  
−
{{Note|This partition should be created before grub_bios-install or grub-setup is run or before the '''Install Bootloader''' step of the Archlinux installer (if GRUB2 BIOS is selected as bootloader).}}
+
For a BIOS-GPT configuration, create a 1007 KiB partition at the beginning of the disk using cgdisk or GNU Parted with no filesystem. The size of 1007 KiB will allow for the following partition to be correctly alligned at 1024 KiB. If needed, the partition can also be located somewhere else on the disk, but it should be within the first 2 TiB region. Set the partition type to {{ic|0xEF02}} in gdisk, {{ic|EF02}} in cgdisk or {{ic|set <BOOT_PART_NUM> bios_grub on}} in GNU Parted.
  
−
===== [[MBR]] aka msdos partitioning specific instructions =====
+
{{Note|This partition should be created before {{ic|grub-install}} or {{ic|grub-setup}} is run.}}
 +
{{Note|gdisk will only allow you to create this partition on the position which will waste the least amount of space (sector 34-2047) if you create it last, after all the other partitions. This is because gdisk will auto-align partitions to 2048-sector boundaries if possible.}}
  
−
Usually the post-MBR gap (after the 512 byte MBR region and before the start of the 1st partition) in many MBR (or msdos disklabel) partitioned systems is 32 KiB when DOS compatibility cylinder alignment issues are satisfied in the partition table. However a post-MBR gap of about 1 to 2 MiB is recommended to provide sufficient room for embedding grub2's core.img ( https://bugs.archlinux.org/task/24103 ). It is advisable to use a partitioner which supports 1 MiB partition alignment to obtain this space as well as satisfy other non-512 byte sector issues (which are unrelated to embedding of core.img).
+
===== [[Master Boot Record]] (MBR) specific instructions =====
 +
Usually the post-MBR gap (after the 512 byte MBR region and before the start of the 1st partition) in many MBR (or msdos disklabel) partitioned systems is 31 KiB when DOS compatibility cylinder alignment issues are satisfied in the partition table. However a post-MBR gap of about 1 to 2 MiB is recommended to provide sufficient room for embedding GRUB2's {{ic|core.img}} ({{bug|24103}}). It is advisable to use a partitioner which supports 1 MiB partition alignment to obtain this space as well as satisfy other non-512 byte sector issues (which are unrelated to embedding of {{ic|core.img}}).
  
−
If you do not dual-boot with MS Windows (any version) in BIOS systems, it is advisable to switch to GPT partitioning - [[GUID_Partition_Table#Convert_from_MBR_to_GPT_without_data_loss]]
+
MBR partitioning has better support in other operating systems, such as Microsoft Windows (up to Windows 7) and Haiku, than GPT partitioning. If you dual boot another operating system, consider using MBR partitioning.
  
−
{{Note|Create the 2MiB partition mentioned above BEFORE you convert to GPT. If you do not, gparted will not resize your boot partition to allow its creation, and when you reboot grub2 will not know where to look.}}
+
A MBR disk may be convertible to GPT if there is a small amount of extra space available. See [[GUID Partition Table#Convert from MBR to GPT]]
  
 
==== UEFI systems ====
 
==== UEFI systems ====
 +
{{Note|It is recommended to read and understand the [[Unified Extensible Firmware Interface|UEFI]], [[GUID Partition Table|GPT]] and [[UEFI Bootloaders]] pages.}}
  
−
===== Create and Mount the UEFI SYSTEM PARTITION =====
+
===== Create and Mount the UEFI System Partition =====
−
 
+
Follow [[Unified Extensible Firmware Interface#EFI System Partition]] for instructions on creating a UEFI SYSTEM PARTITION. Then mount the UEFI SYSTEM PARTITION at {{ic|/boot/efi}}. If you have mounted the UEFISYS partition in some other mountpoint, replace {{ic|/boot/efi}} in the below instructions with that mountpoint:
−
Follow [[Unified_Extensible_Firmware_Interface#Create_an_UEFI_SYSTEM_PARTITION_in_Linux]] for instructions on creating a UEFI SYSTEM PARTITION. Then mount the UEFI SYSTEM PARTITION at {{ic|/boot/efi}}. It should be FAT32 formatted and should be >=200 MiB in size. If you have mounted the UEFISYS partition in some other mountpoint, replace {{ic|/boot/efi}} in the below instructions with that mountpoint:
 
  
 
  # mkdir -p /boot/efi
 
  # mkdir -p /boot/efi
 
  # mount -t vfat <UEFISYS_PART_DEVICE> /boot/efi
 
  # mount -t vfat <UEFISYS_PART_DEVICE> /boot/efi
  
−
Create a <UEFI_SYSTEM_PARTITION>/efi directory if it does not exist:
+
Create a <UEFI_SYSTEM_PARTITION>{{ic|/EFI}} directory, if it does not exist:
  
−
  # mkdir -p /boot/efi/efi
+
  # mkdir -p /boot/efi/EFI
  
 
== Installation ==
 
== Installation ==
  
−
=== During Arch Linux installation ===
+
=== BIOS systems ===
  
−
* Skip the '''Install Bootloader''' step and exit the installer.
+
==== Backup Important Data ====
−
* Configure the network:
 
−
# aif -p partial-configure-network
 
−
This will bring up a prompt; put in the network interface to use, (e.g., eth0) and use DHCP for easy configuration.
 
−
* If you did not configure the installed system's {{ic|/etc/resolv.conf}} file during installation (for instance, if you plan to let DHCP generate it later), you will need to copy the one generated by AIF when it configured the network:
 
−
# cp /etc/resolv.conf /tmp/install/etc/resolv.conf
 
−
* If you run into network issues in the pacman update step below, you may have needed to install the net-tools package.
 
−
* Load the dm-mod module (you might need grub2-bios; install the package if needed):
 
−
# modprobe dm-mod
 
−
{{Note|This is necessary at this point, and cannot be postponed after the chroot. If you try to use modprobe in a chroot environment that has a later kernel version from that of the installing device (at the time of writing, 2.6.33), modprobe will fail. This happens routinely using the Arch "net" installations.}}
 
−
* From the installer's live shell, chroot to the installed system:
 
−
# mount -o bind /dev /mnt/dev
 
−
# mount -t proc /proc /mnt/proc/
 
−
# mount -t sysfs /sys /mnt/sys/
 
−
# chroot /mnt bash
 
−
* Update pacman's database:
 
−
# pacman-db-upgrade
 
−
* Refresh the package list (with an extra -y flag to force a refresh of all package lists even if they appear to be up to date):
 
−
# pacman -Syy
 
−
* Install the GRUB2 package as mentioned in the section [[#From a running Arch Linux]]. Note that the dm-mod module has already been loaded, no need to do that again.
 
  
−
=== From a running Arch Linux ===
+
Although a GRUB(2) installation should run smoothly, it is strongly recommended to keep the GRUB Legacy files before installing {{Pkg|grub-bios}}.
  
−
==== BIOS systems ====
+
# mv /boot/grub /boot/grub-legacy
  
−
===== Backup Important Data =====
+
Backup the MBR which contains the boot code and partition table (Replace {{ic|/dev/sd'''X'''}} with your actual disk path)
  
−
In general, a grub installation should run smoothly. Sometimes it could mess up your system. You're strongly advised to make a backup before installing grub2-bios.
+
# dd if=/dev/sdX of=/path/to/backup/mbr_backup bs=512 count=1
  
−
* copy grub modules and configuration
+
Only 446 bytes of the MBR contain boot code, the next 64 contain the partition table. If you do not want to overwrite your partition table when restoring, it is strongly advised to backup only the MBR boot code:
  
−
  # cp -a /boot/grub /path/to/backup/
+
  # dd if=/dev/sdX of=/path/to/backup/bootcode_backup bs=446 count=1
  
−
* backup the MBR and GRUB-Legacy stage 1.5
+
If unable to install GRUB2 correctly, see [[#Restore GRUB Legacy]].
  
−
# dd if=/dev/sdX of=/path/to/backup/first-sectors bs=512 count=63
+
==== Install grub-bios package ====
  
−
Replace /dev/sdaX with you disk path (mostly /dev/sda).
+
The GRUB(2) packages can be installed with pacman (and will replace {{Pkg|grub-legacy}} or {{Pkg|grub}}, if it is installed):
 +
 +
# pacman -S grub-bios
  
−
{{Note|This command backs up the partition table too. Be careful while restoring if you've changed your partition setup in the meantime}}
+
{{Note|Simply installing the package won't update the {{ic|/boot/grub/i386-pc/core.img}} file and the GRUB(2) modules in {{ic|/boot/grub/i386-pc}}. You need to update them manually using {{ic|grub-install}} as explained below.}}
  
−
To backup only the MBR boot code use:
+
==== Install grub-bios boot files ====
  
−
# dd if=/dev/sdX of=/path/to/backup/mbr-boot-code bs=440 count=1
+
There are 3 ways to install GRUB(2) boot files in BIOS booting:
 +
*[[#Install to GPT BIOS Boot Partition]] (recommended with [[GPT]])
 +
*[[#Install to 440-byte MBR boot code region]] (recommended with [[MBR]])
 +
*[[#Install to Partition or Partitionless Disk]] (not recommended)
 +
*[[#Generate core.img alone]] (safest method, but requires another BIOS bootloader like [[grub-legacy]] or [[syslinux]] to be installed to chainload {{ic|/boot/grub/i386-pc/core.img}})
  
−
You could now lightly remove {{ic|/boot/grub}} with:
+
{{Note|See http://www.gnu.org/software/grub/manual/html_node/BIOS-installation.html for additional documentation.}}
  
−
# rm -rf /boot/grub
+
===== Install to 440-byte MBR boot code region =====
  
−
and follow the instructions below. You know that if things get nasty, you could reboot your system thanks to an installation media and:
+
To setup {{ic|grub-bios}} in the 440-byte Master Boot Record boot code region, populate the {{ic|/boot/grub}} directory, generate the {{ic|/boot/grub/i386-pc/core.img}} file, embed it in the 31 KiB (minimum size - varies depending on partition alignment) post-MBR gap, and generate the configuration file, run:
  
−
* move old grub-legacy or grub2 files out of the way
+
# modprobe dm-mod
−
 
+
# grub-install --recheck /dev/sda
−
  # mv /boot/grub /boot/grub.nonfunctional
+
  # grub-mkconfig -o /boot/grub/grub.cfg
  
−
* copy grub back to /boot
+
where {{ic|/dev/sda}} is the destination of the installation (in this case the MBR of the first SATA disk). If you use [[LVM]] for your {{ic|/boot}}, you can install GRUB2 on multiple physical disks.
  
−
# cp -a /path/to/backup/grub /boot/
+
{{Note|{{ic|--no-floppy}} has been removed from {{ic|grub-install}} in 2.00~beta2 upstream release, and replaced with {{ic|--allow-floppy}}.}}
  
−
* replace MBR and next 62 sectors of sda with backed up copy (DANGEROUS!)
+
{{Warning|Make sure to check the {{ic|/boot}} directory if you use the latter. Sometimes the {{ic| boot-directory}} parameter creates another {{ic|/boot}} folder inside of {{ic|/boot}}. A wrong install would look like: {{ic|/boot/boot/grub/}}.}}
  
−
# dd if=/path/to/backup/first-sectors of=/dev/sdX bs=512 count=63
+
===== Install to GPT BIOS Boot Partition =====
  
−
{{Note|This command also restores the partition table. Be careful.}}
+
[[GUID Partition Table]] disks do not have a reserved "boot track".  Therefore you must create a BIOS Boot Partition (0xEF02) to hold the GRUB core image.
  
−
To restore only the MBR boot code use:
+
Using GNU Parted, you can set this using a command such as the following:
  
−
  # dd if=/path/to/backup/mbr-boot-code of=/dev/sdX bs=440 count=1
+
  # parted /dev/disk set <partition-number> bios_grub on
  
−
===== Install grub2-bios package =====
+
If you are using gdisk, set the partition type to {{Keypress|0xEF02}}. With partitioning programs that require setting the GUID directly, it should be {{ic|‘21686148-6449-6e6f-744e656564454649’}} (stored on disk as {{ic|"Hah!IdontNeedEFI"}} if interpreted as ASCII).
  
−
The GRUB2 package can be installed with pacman (and will replace {{Pkg|grub}}, if it is installed). Simply installing the package won't update the {{ic|/boot/grub/core.img}} file and the grub2 modules in {{ic|/boot/grub}}. You need to update them manually using grub_bios-install as explained below.
+
{{Warning|Be very careful which partition you select when marking it as a BIOS Boot Partition. When GRUB finds a BIOS Boot Partition during installation, it will automatically overwrite part of it. Make sure that the partition does not contain any other data.}}
−
 
−
# pacman -S grub2-bios
 
  
−
{{Note|Installing grub2-common (a dependency of grub2-bios) 1.99~rc1 or later, may take forever in some systems since the post_install script runs grub-mkconfig and this script does not provide the option {{ic|--no-floppy}}. For more details search this option in the article.}}
+
To setup {{ic|grub-bios}} on a GPT disk, populate the {{ic|/boot/grub}} directory, generate the {{ic|/boot/grub/i386-pc/core.img}} file, and embed it in the BIOS Boot Partition, run:
−
 
 
−
Also load the device-mapper kernel module without which grub-probe does not reliably detect disks and partitions:
 
  
 
  # modprobe dm-mod
 
  # modprobe dm-mod
 +
# grub-install --target=i386-pc --recheck --debug /dev/sda
 +
# mkdir -p /boot/grub/locale
 +
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
  
−
===== Install grub2-bios boot files =====
+
where {{ic|/dev/sda}} is the destination of the installation.
−
 
 
−
There are 3 ways to install grub2 boot files in BIOS booting：
 
−
*[[#Install_to_440-byte_MBR_boot_code_region]] (recommended) ,
 
−
*[[#Install_to_Partition_or_Partitionless_Disk]] (not recommended),
 
−
*[[#Generate_core.img_alone]] (safest method, but requires another BIOS bootloader like [[grub-legacy]] or [[syslinux]] to be installed to chainload {{ic|/boot/grub/core.img}} ).
 
−
 
 
−
====== Install to 440-byte MBR boot code region ======
 
−
 
 
−
To setup grub2-bios in the 440-byte Master Boot Record boot code region, populate the {{ic|/boot/grub}} directory, generate the {{ic|/boot/grub/core.img}} file, and embed it in the 32 KiB (minimum size - varies depending on partition alignment) post-MBR gap (MBR disks) or in BIOS Boot Partition (GPT disks), run:
 
−
 
 
−
# grub_bios-install --boot-directory=/boot --no-floppy --recheck --debug /dev/sda
 
−
 
 
−
where {{ic|/dev/sda}} is the destination of the installation (in this case the MBR of the first SATA disk). If you use [[LVM]] for your {{ic|/boot}}, you can install GRUB2 on multiple physical disks.
 
−
 
 
−
The {{ic|--no-floppy}} tells grub2-bios utilities not to search for any floppy devices which reduces the overall execution time of grub_bios-install on many systems (it will also prevent the issue below from occurring). Otherwise you get an error like this:
 
−
 
 
−
grub-probe: error: Cannot get the real path of '/dev/fd0'
 
−
Auto-detection of a filesystem module failed.
 
−
Please specify the module with the option '--modules' explicitly.
 
  
−
====== Install to Partition or Partitionless Disk ======
+
===== Install to Partition or Partitionless Disk =====
  
−
{{Note|grub2-bios (any version - including upstream bzr repo) does not encourage installation to a partition boot sector or a partitionless disk like grub-legacy or syslinux does. Neither do the Arch devs.}}
+
{{Note|{{ic|grub-bios}} (any version - including upstream Bazaar repo) does not encourage installation to a partition boot sector or a partitionless disk like GRUB Legacy or Syslinux does. This kind of setup is prone to breakage, especially during updates, and is not supported by Arch devs.}}
  
−
To setup grub2-bios to a partition boot sector, to a partitionless disk (also called superfloppy) or to a floppy disk, run (using for example /dev/sda1 as the /boot partition)
+
To set up {{ic|grub-bios}} to a partition boot sector, to a partitionless disk (also called superfloppy) or to a floppy disk, run (using for example {{ic|/dev/sdaX}} as the {{ic|/boot}} partition):
 
   
 
   
−
  # chattr -i /boot/grub/core.img
+
  # modprobe dm-mod
−
  # grub_bios-install --boot-directory=/boot --no-floppy --recheck --force --debug /dev/sda1
+
  # grub-install --target=i386-pc --recheck --debug --force /dev/sdaX
−
  # chattr +i /boot/grub/core.img
+
# chattr -i /boot/grub/i386-pc/core.img
 +
# mkdir -p /boot/grub/locale
 +
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
 +
  # chattr +i /boot/grub/i386-pc/core.img
  
−
You need to use the {{ic|--force}} option to allow usage of blocklists and should not use {{ic|1=--grub-setup=/bin/true}} (which is similar to simply generating core.img).
+
You need to use the {{ic|--force}} option to allow usage of blocklists and should not use {{ic|1=--grub-setup=/bin/true}} (which is similar to simply generating {{ic|core.img}}).
  
−
grub_bios-install will give out warnings like which should give you the idea of what might go wrong with this approach.
+
{{ic|grub-install}} will give out warnings like which should give you the idea of what might go wrong with this approach:
  
−
  /sbin/grub-setup: warn: Attempting to install GRUB to a partitionless disk or to a partition. This is a BAD idea.
+
  /sbin/grub-setup: warn: Attempting to install GRUB to a partitionless disk or to a partition. This is a BAD idea.
−
  /sbin/grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists.
+
  /sbin/grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists.  
 
                         However, blocklists are UNRELIABLE and their use is discouraged.
 
                         However, blocklists are UNRELIABLE and their use is discouraged.
  
−
Without {{ic|--force}} you may get the below error and grub-setup will not setup its boot code in the partition boot sector.
+
Without {{ic|--force}} you may get the below error and {{ic|grub-setup}} will not setup its boot code in the partition boot sector:
 
   
 
   
 
  /sbin/grub-setup: error: will not proceed with blocklists
 
  /sbin/grub-setup: error: will not proceed with blocklists
  
−
With {{ic|--force}} you should get
+
With {{ic|--force}} you should get:
  
 
  Installation finished. No error reported.
 
  Installation finished. No error reported.
  
−
The reason why grub-setup does not by default allow this is because in case of partition or a partitionless disk is that grub2-bios relies on embedded blocklists in the partition bootsector to locate the {{ic|/boot/grub/core.img}} file and the prefix dir {{ic|/boot/grub}}. The sector locations of {{ic|core.img}} may change whenever the filesystem in the partition is being altered (files copied, deleted etc.). For more info see https://bugzilla.redhat.com/show_bug.cgi?id=728742 and https://bugzilla.redhat.com/show_bug.cgi?id=730915.
+
The reason why {{ic|grub-setup}} does not by default allow this is because in case of partition or a partitionless disk is that {{ic|grub-bios}} relies on embedded blocklists in the partition bootsector to locate the {{ic|/boot/grub/i386-pc/core.img}} file and the prefix dir {{ic|/boot/grub}}. The sector locations of {{ic|core.img}} may change whenever the filesystem in the partition is being altered (files copied, deleted etc.). For more info see https://bugzilla.redhat.com/show_bug.cgi?id=728742 and https://bugzilla.redhat.com/show_bug.cgi?id=730915.
  
−
The workaround for this is to set the immutable flag on {{ic|/boot/grub/core.img}} (using chattr command as mentioned above) so that the sector locations of the {{ic|core.img}} file in the disk is not altered. The immutable flag on {{ic|/boot/grub/core.img}} needs to be set only if grub2-bios is installed to a partition boot sector or a partitionless disk, not in case of installtion to MBR or simple generation of {{ic|core.img}} without embedding any bootsector (mentioned above).
+
The workaround for this is to set the immutable flag on {{ic|/boot/grub/i386-pc/core.img}} (using chattr command as mentioned above) so that the sector locations of the {{ic|core.img}} file in the disk is not altered. The immutable flag on {{ic|/boot/grub/i386-pc/core.img}} needs to be set only if {{ic|grub-bios}} is installed to a partition boot sector or a partitionless disk, not in case of installation to MBR or simple generation of {{ic|core.img}} without embedding any bootsector (mentioned above).
  
−
====== Generate core.img alone ======
+
===== Generate core.img alone =====
  
−
To populate the {{ic|/boot/grub}} directory and generate a {{ic|/boot/grub/core.img}} file WITHOUT embedding any grub2-bios bootsector code in the MBR, post-MBR region, or the partition bootsector, add {{ic|1=--grub-setup=/bin/true}} to grub_bios-install:
+
To populate the {{ic|/boot/grub}} directory and generate a {{ic|/boot/grub/i386-pc/core.img}} file '''without''' embedding any {{ic|grub-bios}} bootsector code in the MBR, post-MBR region, or the partition bootsector, add {{ic|1=--grub-setup=/bin/true}} to {{ic|grub-install}}:
 
   
 
   
−
  # grub_bios-install --grub-setup=/bin/true --boot-directory=/boot --no-floppy --recheck --debug /dev/sda
+
  # modprobe dm-mod
 +
# grub-install --target=i386-pc --grub-setup=/bin/true --recheck --debug /dev/sda
 +
# mkdir -p /boot/grub/locale
 +
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
  
−
You can then chainload grub2's core.img from grub-legacy or syslinux as a Linux kernel or a multiboot kernel.
+
You can then chainload GRUB2's {{ic|core.img}} from GRUB Legacy or syslinux as a Linux kernel or a multiboot kernel.
  
−
===== Generate GRUB2 BIOS Config file =====
+
==== Generate GRUB2 BIOS Config file ====
  
−
Finally, generate a configuration for grub2 (this is explained in greater detail in the Configuration section):
+
Finally, generate a configuration for GRUB2 (this is explained in greater detail in the Configuration section):
  
 
  # grub-mkconfig -o /boot/grub/grub.cfg
 
  # grub-mkconfig -o /boot/grub/grub.cfg
  
−
If grub2 complains about "no suitable mode found" while booting, go to [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]] .
+
{{Note|The file path is {{ic|/boot/grub/grub.cfg}}, NOT {{ic|/boot/grub/i386-pc/grub.cfg}}.}}
 +
 
 +
If grub(2) complains about "no suitable mode found" while booting, go to [[#Correct GRUB2 No Suitable Mode Found Error]].
  
 
If {{ic|grub-mkconfig}} fails, convert your {{ic|/boot/grub/menu.lst}} file to {{ic|/boot/grub/grub.cfg}} using:
 
If {{ic|grub-mkconfig}} fails, convert your {{ic|/boot/grub/menu.lst}} file to {{ic|/boot/grub/grub.cfg}} using:
Line 254: Line 240:
 
</nowiki>}}
 
</nowiki>}}
  
−
If you forgot to create a GRUB2 {{ic|/boot/grub/grub.cfg}} configfile and simply rebooted into GRUB2 Command Shell, type:
+
If you forgot to create a GRUB2 {{ic|/boot/grub/grub.cfg}} config file and simply rebooted into GRUB2 Command Shell, type:
  
 
  sh:grub> insmod legacycfg
 
  sh:grub> insmod legacycfg
 
  sh:grub> legacy_configfile ${prefix}/menu.lst
 
  sh:grub> legacy_configfile ${prefix}/menu.lst
  
−
Boot into Arch and re-create the proper GRUB2 {{ic|/boot/grub/grub.cfg}} configfile.
+
Boot into Arch and re-create the proper GRUB2 {{ic|/boot/grub/grub.cfg}} config file.
  
 
{{Note|This option works only in BIOS systems, not in UEFI systems.}}
 
{{Note|This option works only in BIOS systems, not in UEFI systems.}}
  
−
===== Multiboot in BIOS =====
+
==== Multiboot in BIOS ====
  
−
====== Boot Microsoft Windows installed in BIOS-MBR mode ======
+
===== Boot Microsoft Windows installed in BIOS-MBR mode =====
  
−
{{Note|GRUB2 supports booting {{ic|bootmgr}} directly and chainload of partition boot sector is no longer required to boot Windows in a BIOS-MBR setup.}}
+
{{Note|GRUB(2) supports booting {{ic|bootmgr}} directly and chainload of partition boot sector is no longer required to boot Windows in a BIOS-MBR setup.}}
  
−
Find the UUID of the NTFS filesystem of the Windows's SYSTEM PARTITION where the bootmgr and its files reside. For example, if Windows {{ic|bootmgr}} exists at {{ic|/media/Windows/bootmgr}}:
+
{{Warning|Take note that it is the '''system partition''' that has {{ic|bootmgr}}, not your "real" Windows partition (usually C:). When showing all UUIDs with blkid, the system partition is the one with {{ic|LABEL&#61;"SYSTEM RESERVED"}} and is only about 100 MB in size (much like the boot partition for Arch). See http://en.wikipedia.org/wiki/System_partition_and_boot_partition for more info.}}
  
−
  # grub-probe --target=fs_uuid /media/Windows/bootmgr
+
Find the UUID of the NTFS filesystem of the Windows's SYSTEM PARTITION where the {{ic|bootmgr}} and its files reside. For example, if Windows {{ic|bootmgr}} exists at {{ic|/media/SYSTEM_RESERVED/bootmgr}}:
 +
 
 +
For Windows Vista/7/8:
 +
 
 +
  # grub-probe --target=fs_uuid /media/SYSTEM_RESERVED/bootmgr
 
  69B235F6749E84CE
 
  69B235F6749E84CE
  
−
Then, add the below code to {{ic|/etc/grub.d/40_custom}} and regenerate grub.cfg with grub-mkconfig as explained above to chainload Windows (Vista, 7 or 8) installed in BIOS-MBR mode:
+
# grub-probe --target=hints_string /media/SYSTEM_RESERVED/bootmgr
 +
--hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1
 +
 
 +
{{Note|{{ic|grub-probe}} should be run as root.}}
 +
 
 +
{{Note|For Windows XP, replace {{ic|bootmgr}} with {{ic|ntldr}} in the above commands.}}
  
−
menuentry "Microsoft Windows 7 BIOS-MBR" {
+
Then, add the below code to {{ic|/etc/grub.d/40_custom}} or {{ic|/boot/grub/custom.cfg}} and regenerate {{ic|grub.cfg}} with {{ic|grub-mkconfig}} as explained above to boot Windows (XP, Vista, 7 or 8) installed in BIOS-MBR mode:
−
    insmod part_msdos
+
 
−
    insmod ntfs
+
For Windows Vista/7/8:
−
    insmod search_fs_uuid
+
 
−
    insmod ntldr     
+
<pre>
−
    search --fs-uuid --no-floppy --set=root 69B235F6749E84CE
+
menuentry "Microsoft Windows Vista/7/8 BIOS-MBR" {
−
    ntldr (${root})/bootmgr
+
    insmod part_msdos
−
}
+
    insmod ntfs
 +
    insmod search_fs_uuid
 +
    insmod ntldr     
 +
    search --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 69B235F6749E84CE
 +
    ntldr /bootmgr
 +
}</pre>
  
−
For Windows XP
+
For Windows XP:
  
 
  menuentry "Microsoft Windows XP" {
 
  menuentry "Microsoft Windows XP" {
Line 292: Line 292:
 
     insmod search_fs_uuid
 
     insmod search_fs_uuid
 
     insmod ntldr     
 
     insmod ntldr     
−
     search --fs-uuid --no-floppy --set=root 69B235F6749E84CE
+
     search --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 69B235F6749E84CE
−
     ntldr (${root})/ntldr
+
     ntldr /ntldr
 
  }
 
  }
  
−
==== [[UEFI]] systems ====
+
{{ic|/etc/grub.d/40_custom}} can be used as a template to create {{ic|/etc/grub.d/nn_custom}}.  Where nn defines the precendence, indicating the order the script is executed.  The order scripts are executed determine the placement in the grub boot menu.
 +
 
 +
{{Note| nn should be greater than 06 to ensure necessary scripts are executed first.}}
 +
 
 +
=== UEFI systems ===
 +
 
 +
{{Note|It is recommended to read the [[Unified Extensible Firmware Interface|UEFI]], [[GUID Partition Table|GPT]] and [[UEFI Bootloaders]] pages before reading this part.}}
 +
 
 +
==== Hardware-Specific UEFI Examples ====
  
−
===== Install grub2-uefi package =====
+
It is well know that different motherboard manufactures implement UEFI differently.  Users experiencing problems getting Grub/EFI to work properly are encouraged to share detailed steps for hardware-specific cases where UEFI booting does not work as described below.  In an effort to keep the parent [[GRUB]] article neat and tidy, see the [[GRUB EFI Examples]] page for these special cases.
  
−
{{Note|Unless specified as EFI 1.x , EFI and UEFI terms are used interchangeably to denote UEFI 2.x firmware. Also unless stated explicitely, the instructions are general and not Mac specific. Some of them may not work or may be different in Macs. Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one UEFI Specification version and is therefore not a standard UEFI firmware.}}
+
==== Install grub-uefi package ====
  
−
GRUB2 UEFI bootloader is available in Arch Linux only from version 1.99~rc1. To install, first [https://wiki.archlinux.org/index.php/Unified_Extensible_Firmware_Interface#Detecting_UEFI_Firmware_Arch Detect which UEFI firmware arch] you have (either x86_64 or i386).
+
{{Note|Unless specified as EFI 1.x , EFI and UEFI terms are used interchangeably to denote UEFI 2.x firmware. Also unless stated explicitly, the instructions are general and not Mac specific. Some of them may not work or may be different in Macs. Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one UEFI Specification version and is therefore not a standard UEFI firmware.}}
 +
 
 +
GRUB(2) UEFI bootloader is available in Arch Linux only from version 1.99~rc1. To install, first [[Unified Extensible Firmware Interface#Detecting UEFI Firmware Arch|detect which UEFI firmware arch]] you have (either x86_64 or i386).
  
 
Depending on that, install the appropriate package
 
Depending on that, install the appropriate package
  
 
For 64-bit aka x86_64 UEFI firmware:
 
For 64-bit aka x86_64 UEFI firmware:
−
  # pacman -S grub2-efi-x86_64
+
  # pacman -S grub-efi-x86_64
  
 
For 32-bit aka i386 UEFI firmware:
 
For 32-bit aka i386 UEFI firmware:
−
  # pacman -S grub2-efi-i386
+
  # pacman -S grub-efi-i386
  
−
{{Note|Installing grub2-common (a dependency of grub2-bios) 1.99~rc1 or later, may take forever in some systems since the post_install script runs grub-mkconfig and this script does not provide the option {{ic|--no-floppy}}. For more details search this option in the article.}}
+
{{Note|Simply installing the package will not update the {{ic|core.efi}} file and the GRUB(2) modules in the UEFI System Partition. You need to do this manually using {{ic|grub-install}} as explained below.}}
  
−
{{Note|Simply installing the package won't update the grub.efi file and the grub2 modules in the UEFI System Partition. You need to update the grub.efi file and the grub2 modules in the UEFI System Partition manually using grub_efi_${UEFI_ARCH}-install as explained below.}}
+
==== Install grub-uefi boot files ====
  
−
Also load the device-mapper kernel module without which grub-probe does not reliably detect disks and partitions
+
===== Install to UEFI System Partition =====
  
−
# modprobe dm-mod
+
{{Note|The below commands assume you are using {{ic|grub-efi-x86_64}} (for {{ic|grub-efi-i386}} replace {{ic|x86_64}} with {{ic|i386}} in the below commands).}}
  
−
===== Install grub2-uefi boot files =====
+
{{Note|To do this, you need to boot using UEFI and not the BIOS. If you booted by just copying the ISO file to the USB drive, you will need to follow [[Unified Extensible Firmware Interface#Create UEFI bootable USB from ISO|this guide]] or grub-install will show errors.}}
  
−
====== Install to UEFI SYSTEM PARTITION ======
+
The UEFI system partition will need to be mounted at {{ic|/boot/efi/}} for the GRUB(2) install script to detect it:
  
−
{{Note|The below commands assume you are using {{ic|grub2-efi-x86_64}} (for {{ic|grub2-efi-i386}} replace {{ic|x86_64}} with {{ic|i386}} in the below commands).}}
+
# mkdir -p /boot/efi
 +
# mount -t vfat /dev/sdXY /boot/efi
  
−
# grub_efi_x86_64-install --root-directory=/boot/efi --boot-directory=/boot/efi/efi --bootloader-id=grub --no-floppy --recheck --debug
+
Install GRUB UEFI application to {{ic|/boot/efi/EFI/arch_grub}} and its modules to {{ic|/boot/grub/x86_64-efi}} (recommended) using:
  
−
The {{ic|grub_efi_x86_64-install}} automatically generates a {{ic|grub.efi}} while setting up the {{ic|/boot/efi/efi/grub/}} directory.
+
# modprobe dm-mod
 +
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --recheck --debug
 +
# mkdir -p /boot/grub/locale
 +
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
  
−
If you notice carefully, there is no <device_path> option (Eg: {{ic|/dev/sda}}) at the end of the {{ic|grub_efi_x86_64-install}} command unlike the case of setting up grub2 for BIOS systems. Any <device_path> provided will be ignored by the install script as UEFI bootloaders do not use MBR or Partition boot sectors at all.
+
{{Note|Without {{ic|--target}} or {{ic|--directory}} option, grub-install cannot determine for which firmware grub(2) is being installed. In such cases grub-install will show {{ic|source_dir doesn't exist. Please specify --target or --directory}} message.}}
  
−
You may now be able to UEFI boot your system by creating a grub.cfg file by following [[#Generate_GRUB2_UEFI_Config_file]] and copying /boot/efi/efi/grub/grubx64.efi to /boot/efi/efi/boot/bootx64.efi.
+
If you want to install grub(2) modules and {{ic|grub.cfg}} at the directory {{ic|/boot/efi/EFI/grub}} and the {{ic|grubx64.efi}} application at {{ic|/boot/efi/EFI/arch_grub}} (ie. all the grub(2) uefi files inside the UEFISYS partition itself) use:
  
−
===== Create GRUB2 entry in the Firmware Boot Manager =====
+
# modprobe dm-mod
 +
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --boot-directory=/boot/efi/EFI --recheck --debug
 +
# mkdir -p /boot/efi/EFI/grub/locale
 +
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/efi/EFI/grub/locale/en.mo
  
−
====== Non-Mac UEFI systems ======
+
The {{ic|--efi-directory}} option mentions the mountpoint of UEFI SYSTEM PARTITION , {{ic|--bootloader-id}} mentions the name of the directory used to store the {{ic|grubx64.efi}} file and {{ic|--boot-directory}} mentions the directory wherein the actual modules will be installed (and into which {{ic|grub.cfg}} should be created).
  
−
{{Note|The below steps will not work if the system has been booted in BIOS mode and will not work if the UEFI processor architecture does not match the kernel one, i.e. x86_64 UEFI + ix86 32-bit Kernel and vice-versa config will not work. This is true only for efivars kernel module and efibootmgr step. The other steps (ie. upto setting up <UEFISYS>/efi/grub/grub.{efi,cfg} ) can be done even in BIOS/Legacy boot mode.}}
+
The actual paths are:
  
−
{{Warning|Using {{ic|efibootmgr}} in Apple Macs will brick the firmware and may need reflash of the motherboard ROM. There have been bug reports regarding this in Ubuntu/Launchpad bug tracker. Use bless command alone in case of Macs (see chapter regarding Apple systems}}
+
<efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi
  
 +
<boot-directory>/grub/x86_64-efi/<all modules, grub.efi, core.efi, grub.cfg>
  
−
grub_efi_${UEFI_ARCH}-install will ensure {{ic|/boot/efi/efi/grub/grub.efi}} is launched by default if it detects {{ic|efibootmgr}} and if it is able to access UEFI Runtime Services. {{ic|efibootmgr}} command will work only if you have booted the system in UEFI mode itself, since it '''requires access to UEFI Runtime Variables''' which are '''available only in UEFI boot mode''' (with "noefi" kernel parameter NOT being used).  Initially the user is required to manually launch {{ic|/boot/efi/efi/grub/grub.efi}} from the firmware itself (using maybe the UEFI Shell) if grub2-efi was installed in BIOS mode. Then {{ic|efibootmgr}} should be run to make grub2 as the default entry in the UEFI Boot Manager
+
{{Note|the {{ic|--bootloader-id}} option does not change {{ic|<boot-directory>/grub}}, i.e. you cannot install the modules to {{ic|<boot-directory>/<bootloader-id>}}, the path is hard-coded to be {{ic|<boot-directory>/grub}}.}}
  
−
First boot into UEFI mode manually either using the firmware boot menu, UEFI shell, or using any UEFI capable bootable iso (Archboot or Ubuntu non-Mac iso). Use grub probe to determine the device path of your EFI System Partition:
+
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=grub</nowiki>}}:
−
# grub-probe --target=device /boot/efi/efi/grub/grub.efi
 
  
−
It should give something like {{ic|/dev/sda1}} (used as example in the remaining steps). Load 'efivars' kernel module:
+
<efi-directory>/<EFI or efi>/<bootloader-id> == <boot-directory>/grub == /boot/efi/EFI/grub
−
# modprobe efivars
 
  
−
If you get '''no such device found''' error for this command, that means you have not booted in UEFI mode or due to some reason the kernel is unable to access UEFI Runtime Variables.
+
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=arch_grub</nowiki>}}:
  
−
Verify whether there are files in ''/sys/firmware/efi/vars/'' directory. This directory and its contents are created by "efivars" kernel module and it will exist only if you have booted in UEFI mode without the "noefi" kernel parameter.
+
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub
−
+
  <boot-directory>/grub == /boot/efi/EFI/grub
−
  # ls -1 /sys/firmware/efi/vars/
 
  
−
Sample output (x86_64-UEFI 2.3.1 in x86_64 Kernel:
+
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=arch_grub</nowiki>}}:
−
 
−
# ls -1 /sys/firmware/efi/vars/
 
−
Boot0000-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
BootCurrent-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
BootOptionSupport-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
BootOrder-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
ConIn-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
ConInDev-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
ConOut-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
ConOutDev-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
ErrOutDev-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
Lang-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
LangCodes-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
MTC-eb704011-1402-11d3-8e77-00a0c969723b/
 
−
MemoryTypeInformation-4c19049f-4137-4dd3-9c10-8b97a83ffdfa/
 
−
PlatformLang-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
PlatformLangCodes-8be4df61-93ca-11d2-aa0d-00e098032b8c/
 
−
RTC-378d7b65-8da9-4773-b6e4-a47826a833e1/
 
−
del_var
 
−
new_var
 
  
−
If ''/sys/firmware/efi/vars/'' directory is empty or does not exist, then {{ic|efibootmgr}} command will not work. If you are unable to make the ISO/CD/DVD/USB boot in UEFI mode try https://gitorious.org/tianocore_uefi_duet_builds/pages/Linux_Windows_BIOS_UEFI_boot_USB.
+
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub
 +
<boot-directory>/grub == /boot/grub
  
−
If ''/sys/firmware/efi/vars/'' directory (along with the exists then run {{ic|efibootmgr}} and reboot:
+
In {{ic|<nowiki>--efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=grub</nowiki>}}:
−
 
−
# efibootmgr --create --gpt --disk /dev/sda --part 1 --write-signature --label "GRUB2" --loader "\\EFI\\grub\\grub.efi"
 
  
−
In the above command, {{ic|/boot/efi/efi/grub/grub.efi}} can be split up as {{ic|/boot/efi}} and {{ic|/efi/grub/grub.efi}}, which translates to {{ic|(/dev/sda)}} -> partition 1 -> {{ic|\\EFI\\grub\\grub.efi}}.
+
<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/grub
 +
<boot-directory>/grub == /boot/grub
  
−
FAT32 filesystem is case-insensitive since it does not use UTF-8 encoding by default. In that case the firmware uses capital 'EFI' instead of small 'efi', therefore using {{ic|\\EFI\\grub\\grub.efi}} or {{ic|\\efi\\grub\\grub.efi}} does not matter (this will change if the filesystem encoding is UTF-8). UEFI uses backward slash as path separatoir (similar to Windows paths). In the above command "double" backward slashes are used instead of single ones, since a backward slash is used as a escape character by sh shells, the first backward slash escapes the second one so that the path {{ic|\EFI\grub\grub.efi}} is passed to {{ic|efibootmgr}}.
+
The {{ic|<nowiki><efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi</nowiki>}} is an exact copy of {{ic|<nowiki><boot-directory>/grub/x86_64-efi/core.efi</nowiki>}}.
  
−
The 'label' is the name of the menu entry shown in the UEFI boot menu. This name is user's choice and does not affect the booting of the system. More info can be obtained from [http://linux.dell.com/cgi-bin/gitweb/gitweb.cgi?p=efibootmgr.git;a=blob_plain;f=README;hb=HEAD efibootmgr GIT README]
+
{{Note|In GRUB 2.00, the {{ic|grub-install}} option {{ic|--efi-directory}} replaces {{ic|--root-directory}} and the latter is deprecated.}}
  
−
If you have problems running GRUB2 in UEFI mode you can try the following (worked on an ASUS Z68 mainboard):
+
{{Note|The options {{ic|--efi-directory}} and {{ic|--bootloader-id}} are specific to GRUB(2) UEFI.}}
 
   
 
   
−
# cp /boot/efi/efi/grub/grubx64.efi /boot/efi/shellx64.efi
+
In all the cases the UEFI SYSTEM PARTITION should be mounted for {{ic|grub-install}} to install {{ic|grubx64.efi}} in it, which will be launched by the firmware (using the {{ic|efibootmgr}} created boot entry in non-Mac systems).
 +
 
 +
If you notice carefully, there is no <device_path> option (Eg: {{ic|/dev/sda}}) at the end of the {{ic|grub-install}} command unlike the case of setting up GRUB(2) for BIOS systems. Any <device_path> provided will be ignored by the install script as UEFI bootloaders do not use MBR or Partition boot sectors at all.
  
−
or
+
You may now be able to UEFI boot your system by creating a {{ic|grub.cfg}} file by following [[#Generate GRUB2 UEFI Config file]] and [[#Create GRUB2 entry in the Firmware Boot Manager]].
−
 
−
# cp /boot/efi/efi/grub/grubx64.efi /boot/efi/efi/shellx64.efi
 
−
or
 
  
−
# cp /boot/efi/efi/grub/grubx64.efi /boot/efi/efi/shell/shellx64.efi
+
==== Generate GRUB2 UEFI Config file ====
  
−
After this launch the UEFI Shell from the UEFI setup/menu (in ASUS UEFI BIOS, switch to advanced mode, press Exit in the top right corner and choose "Launch EFI shell from filesystem device"). The grub2 menu will show up and you can boot into your system. Afterwards you can use efibootmgr to setup a menu entry (see above).
+
Finally, generate a configuration for GRUB(2) (this is explained in greater detail in the Configuration section):
  
−
====== Apple Mac EFI systems ======
+
# grub-mkconfig -o <boot-directory>/grub/grub.cfg
  
−
Use bless command from within Mac OS X to set {{ic|grub.efi}} as the default boot option. You can also boot from the Mac OS X install disc and launch a Terminal there if you only have Linux installed. In the Terminal, create a directory and mount the EFI System Partition:
+
{{Note|The file path is {{ic|<boot-directory>/grub/grub.cfg}}, NOT {{ic|<boot-directory>/grub/x86_64-efi/grub.cfg}}.}}
  
−
# cd /Volumes
+
If you used {{ic|<nowiki>--boot-directory=/boot</nowiki>}}:
−
# mkdir efi
 
−
# mount -t msdos /dev/disk0s1 /Volumes/efi
 
  
−
Then run bless on {{ic|grub.efi}} and on the EFI partition to set them as the default boot options.
+
# grub-mkconfig -o /boot/grub/grub.cfg
  
−
# bless --folder=/Volumes/efi --file=/Volumes/efi/efi/grub/grub.efi --setBoot
+
If you used {{ic|<nowiki>--boot-directory=/boot/efi/EFI</nowiki>}}:
−
# bless --mount=/Volumes/efi --file=/Volumes/efi/efi/grub/grub.efi --setBoot
 
  
−
More info at https://help.ubuntu.com/community/UEFIBooting#Apple_Mac_EFI_systems_.28both_EFI_architecture.29.
+
# grub-mkconfig -o /boot/efi/EFI/grub/grub.cfg
  
−
===== Generate GRUB2 UEFI Config file =====
+
This is independent of the value of {{ic|--bootloader-id}} option.
  
−
Finally, generate a configuration for grub2 (this is explained in greater detail in the Configuration section):
+
If GRUB2 complains about "no suitable mode found" while booting, try [[#Correct GRUB2 No Suitable Mode Found Error]].
  
−
# grub-mkconfig -o /boot/efi/efi/grub/grub.cfg
+
==== Create GRUB2 entry in the Firmware Boot Manager ====
  
−
If grub2-uefi complains about "no suitable mode found" while booting, go to [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]].
+
As of grub-efi-x86_64 version 2.00, {{ic|grub-install}} automatically tries to create a menu entry in the boot manager. If it doesn't, then see [[Beginners' Guide#GRUB]] for instructions to use {{ic|efibootmgr}} to create a menu entry. However, the problem is likely to be that you haven't booted your CD/USB in UEFI mode, as in [[Unified Extensible Firmware Interface#Create UEFI bootable USB from ISO]].
  
−
===== Create GRUB2 Standalone UEFI Application =====
+
==== Create GRUB2 Standalone UEFI Application ====
  
−
It is possible to create a grub_standalone.efi application which has all the modules embeddded in a memdisk within the uefi application, thus removing the need for having a separate directory populated with all the grub2 uefi modules and other related files.  
+
It is possible to create a {{ic|grubx64_standalone.efi}} application which has all the modules embeddded in a memdisk within the uefi application, thus removing the need for having a separate directory populated with all the GRUB2 uefi modules and other related files. This is done using the {{ic|grub-mkstandalone}} command which is included in {{Pkg|grub-common}} >= 1:1.99-6 package.
  
 
The easiest way to do this would be with the install command already mentioned before, but specifying the modules to include. For example:
 
The easiest way to do this would be with the install command already mentioned before, but specifying the modules to include. For example:
  
−
  # grub_efi_x86_64-install --root-directory=/boot/efi --boot-directory=/boot/efi/efi --bootloader-id=grub --no-floppy --recheck --debug \
+
  # grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \
−
  --modules="normal help ext2 video efi_gop gfxterm gzio"
+
  --output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" <any extra files you want to include>
  
−
However, you might want to embed certain configuration as well, for which you might want to use a script like this:
+
The {{ic|grubx64_standalone.efi}} file expects {{ic|grub.cfg}} to be within its $prefix which is {{ic|(memdisk)/boot/grub}}. The memdisk is embedded within the efi app. The {{ic|grub-mkstandlone}} script allow passing files to be included in the memdisk image to be as the arguments to the script (in <any extra files you want to include>).
  
−
{{hc|grub_image_helper|
+
If you have the {{ic|grub.cfg}} at {{ic|/home/user/Desktop/grub.cfg}}, then create a temporary {{ic|/home/user/Desktop/boot/grub/}} directory, copy the {{ic|/home/user/Desktop/grub.cfg}} to {{ic|/home/user/Desktop/boot/grub/grub.cfg}}, cd into {{ic|/home/user/Desktop/boot/grub/}} and run:
−
<nowiki>
 
−
#!/bin/bash
 
  
−
ARCH=${1:-x86_64-efi}
+
# grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \
 +
--output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" "boot/grub/grub.cfg"
  
−
cat << EOF > "grub.cfg"
+
The reason to cd into {{ic|/home/user/Desktop/boot/grub/}} and to pass the file path as {{ic|boot/grub/grub.cfg}} (notice the lack of a leading slash - boot/ vs /boot/ ) is because {{ic|dir1/dir2/file}} is included as {{ic|(memdisk)/dir1/dir2/file}} by the {{ic|grub-mkstandalone}} script.
−
search --no-floppy --fs-uuid --set=grub_root 5EF2-55E6
 
−
set prefix=(\$grub_root)/efi/grub
 
−
EOF
 
  
−
grub-mkimage --format=$ARCH --compression=xz --output=/boot/efi/efi/grub/grub_standalone.efi --config grub.cfg '--prefix=(,gpt1)/efi/grub' fat part_gpt search</nowiki>}}
+
If you pass {{ic|/home/user/Desktop/grub.cfg}} the file will be included as {{ic|(memdisk)/home/user/Desktop/grub.cfg}}. If you pass {{ic|/home/user/Desktop/boot/grub/grub.cfg}} the file will be included as {{ic|(memdisk)/home/user/Desktop/boot/grub/grub.cfg}}. That is the reason for cd'ing into {{ic|/home/user/Desktop/boot/grub/}} and passing {{ic|boot/grub/grub.cfg}}, to include the file as {{ic|(memdisk)/boot/grub/grub.cfg}}, which is what {{ic|grub.efi}} expects the file to be.
  
−
You would need to create an entry with {{ic|efibootmgr}} for grub_standalone.efi, just use grub.efi instead to replace the original, or you can use the UEFI shell to try it out first. See [[#Create GRUB2 entry in the Firmware Boot Manager]].
+
You need to create an UEFI Boot Manager entry for {{ic|/boot/efi/EFI/arch_grub/grubx64_standalone.efi}} using {{ic|efibootmgr}}. Follow [[#Create GRUB2 entry in the Firmware Boot Manager]].
  
−
===== Multiboot in UEFI =====
+
==== Multiboot in UEFI ====
  
−
====== Chainload Microsoft Windows x86_64 UEFI-GPT ======
+
===== Chainload Microsoft Windows x86_64 UEFI-GPT =====
  
−
Find the UUID of the FAT32 filesystem in the UEFI SYSTEM PARTITION where the Windows UEFI Bootloader files reside. For example, if Windows {{ic|bootmgfw.efi}} exists at {{ic|/boot/efi/efi/Microsoft/Boot/bootmgfw.efi}} (ignore the upper-lower case differences since that is immaterial in FAT filesystem):
+
Find the UUID of the FAT32 filesystem in the UEFI SYSTEM PARTITION where the Windows UEFI Bootloader files reside. For example, if Windows {{ic|bootmgfw.efi}} exists at {{ic|/boot/efi/EFI/Microsoft/Boot/bootmgfw.efi}} (ignore the upper-lower case differences since that is immaterial in FAT filesystem):
  
−
  # grub-probe --target=fs_uuid /boot/efi/efi/Microsoft/Boot/bootmgfw.efi
+
  # grub-probe --target=fs_uuid /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi
 
  1ce5-7f28
 
  1ce5-7f28
  
−
Then, add this code to {{ic|/boot/efi/efi/grub/grub.cfg}} to chainload Windows x86_64 (Vista SP1+, 7 or 8) installed in UEFI-GPT mode:
+
# grub-probe --target=hints_string /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi
 +
--hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1
 +
 
 +
{{Note|{{ic|grub-probe}} should be run as root.}}
 +
 
 +
Then, add this code to {{ic|/etc/grub.d/40_custom}} to chainload Windows x86_64 (Vista SP1+, 7 or 8) installed in UEFI-GPT mode:
  
−
  menuentry "Microsoft Windows x86_64 UEFI-GPT" {
+
  menuentry "Microsoft Windows Vista/7/8 x86_64 UEFI-GPT" {
 
     insmod part_gpt
 
     insmod part_gpt
 
     insmod fat
 
     insmod fat
 
     insmod search_fs_uuid
 
     insmod search_fs_uuid
 
     insmod chain
 
     insmod chain
−
     search --fs-uuid --no-floppy --set=root 1ce5-7f28
+
     search --fs-uuid --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1 1ce5-7f28
−
     chainloader (${root})/efi/Microsoft/Boot/bootmgfw.efi
+
     chainloader /efi/Microsoft/Boot/bootmgfw.efi
 
  }
 
  }
 +
 +
Afterwards remake {{ic|/boot/grub/grub.cfg}}
 +
 +
# grub-mkconfig -o /boot/grub/grub.cfg
  
 
== Configuration ==
 
== Configuration ==
Line 477: Line 473:
 
You can also choose to automatically generate or manually edit {{ic|grub.cfg}}.
 
You can also choose to automatically generate or manually edit {{ic|grub.cfg}}.
  
−
{{Note|If using UEFI {{ic|grub.cfg}} must be placed alongside {{ic|grub.efl}} on the UEFI system partition. The easiest way is to copy the configuration file created below from {{ic|/boot/grub/grub.cfg}} to {{ic|/boot/efi/EFI/grub}} where {{ic|/boot/efi}} is the mounted UEFI partition. }}
+
{{Note|For EFI systems, if GRUB2 was installed with the {{ic|--boot-directory}} option set, the {{ic|grub.cfg}} file must be placed in the same directory as {{ic|grubx64.efi}}. Otherwise, the {{ic|grub.cfg}} file goes in {{ic|/boot/grub/}}, just like in the BIOS version of GRUB2.}}
 +
 
 +
{{Note|Here is a quite complete description of how to configure GRUB2: http://members.iinet.net/~herman546/p20/GRUB2%20Configuration%20File%20Commands.html }}
  
 
=== Automatically generating using grub-mkconfig (Recommended) ===
 
=== Automatically generating using grub-mkconfig (Recommended) ===
  
−
The GRUB2 {{ic|menu.1st}} equivalent configuration files are {{ic|/etc/default/grub}} and {{ic|/etc/grub.d/*}}. grub-mkconfig uses these files to generate {{ic|grub.cfg}}. By default the script outputs to stdout. To generate a {{ic|grub.cfg}} file run the command:
+
The GRUB2 {{ic|menu.lst}} equivalent configuration files are {{ic|/etc/default/grub}} and {{ic|/etc/grub.d/*}}. {{ic|grub-mkconfig}} uses these files to generate {{ic|grub.cfg}}. By default the script outputs to stdout. To generate a {{ic|grub.cfg}} file run the command:
 +
 
 
  # grub-mkconfig -o /boot/grub/grub.cfg
 
  # grub-mkconfig -o /boot/grub/grub.cfg
−
{{ic|/etc/grub.d/10_linux}} is set to automatically add menu items for Arch linux that work out of the box, to any generated configuration. Other operating systems may need to be added manually by editing {{ic|/etc/grub.d/40_custom}}
+
 
 +
{{ic|/etc/grub.d/10_linux}} is set to automatically add menu items for Arch linux that work out of the box, to any generated configuration. Other operating systems may need to be added manually to {{ic|/etc/grub.d/40_custom}} or {{ic|/boot/grub/custom.cfg}}
 +
 
 +
==== Additional arguments ====
 +
 
 +
To pass custom additional arguments to the Linux image, you can set the {{ic|GRUB_CMDLINE_LINUX}} variable in {{ic|/etc/default/grub}}.
 +
 
 +
For example, use {{ic|<nowiki>GRUB_CMDLINE_LINUX="resume=/dev/sdaX"</nowiki>}} where {{ic|sda'''X'''}} is your swap partition to enable resume after hibernation.
 +
 
 +
You can also use {{ic|<nowiki>GRUB_CMDLINE_LINUX="resume=/dev/disk/by-uuid/${swap_uuid}"</nowiki>}}, where {{ic|${swap_uuid} }} is the [[Persistent_block_device_naming|UUID]] of your swap partition.
 +
 
 +
Multiple entries are separated by spaces within the double quotes.  So, for users who want both resume and systemd it would look like this:
 +
{{ic|<nowiki>GRUB_CMDLINE_LINUX="resume=/dev/sdaX init=/usr/lib/systemd/systemd"</nowiki>}}
 +
 
 +
See [[Kernel parameters]] for more info.
  
 
=== Manually creating grub.cfg ===
 
=== Manually creating grub.cfg ===
  
−
A basic grub file uses the following options
+
{{Warning|Editing this file is strongly ''not'' recommended. The file is generated by the {{ic|grub-mkconfig}} command, and it is best to edit your {{ic|/etc/default/grub}} or one of the scripts in the {{ic|/etc/grub.d}} folder.}}
 +
 
 +
A basic GRUB config file uses the following options
 
* {{ic|(hdX,Y)}} is the partition {{ic|Y}} on disk {{ic|X}}, partition numbers starting at 1, disk numbers starting at 0
 
* {{ic|(hdX,Y)}} is the partition {{ic|Y}} on disk {{ic|X}}, partition numbers starting at 1, disk numbers starting at 0
 
* {{ic|1=set default=N}} is the default boot entry that is chosen after timeout for user action
 
* {{ic|1=set default=N}} is the default boot entry that is chosen after timeout for user action
Line 520: Line 535:
 
# (0) Arch Linux
 
# (0) Arch Linux
 
menuentry "Arch Linux" {
 
menuentry "Arch Linux" {
−
set root=(hd0,1)
+
    set root=(hd0,1)
−
linux /vmlinuz-linux root=/dev/sda3 ro
+
    linux /vmlinuz-linux root=/dev/sda3 ro
−
initrd /initramfs-linux.img
+
    initrd /initramfs-linux.img
 
}
 
}
  
Line 534: Line 549:
 
=== Dual-booting ===
 
=== Dual-booting ===
  
−
''NOTE: If you want GRUB2 to automatically search for other systems, for example as in Ubuntu. Then you may need to download {{AUR|os-prober}} from the [[AUR]].''
+
{{Note|If you want GRUB2 to automatically search for other systems, you may wish to install {{Pkg|os-prober}}.}}
  
 
==== Using grub-mkconfig ====
 
==== Using grub-mkconfig ====
−
The best way to add other entries is editing the {{ic|/etc/grub.d/40_custom}}. The entries in this file will be automatically added when running '''grub-mkconfig'''.
+
The best way to add other entries is editing the {{ic|/etc/grub.d/40_custom}} or {{ic|/boot/grub/custom.cfg}} . The entries in this file will be automatically added when running {{ic|grub-mkconfig}}.
 
After adding the new lines, run:
 
After adding the new lines, run:
 
  # grub-mkconfig -o /boot/grub/grub.cfg  
 
  # grub-mkconfig -o /boot/grub/grub.cfg  
Line 563: Line 578:
 
===== With Windows =====
 
===== With Windows =====
  
−
This assumes that your Windows partition is {{ic|sda3}}.
+
This assumes that your Windows partition is {{ic|sda3}}. Remember you need to point set root and chainloader to the system reserve partition that windows made when it installed, not the actual partition windows is on. This example works if your system reserve partition is {{ic|sda3}}.
  
 
  # (2) Windows XP
 
  # (2) Windows XP
Line 571: Line 586:
 
  }
 
  }
  
−
If the windows bootloader is on an entirely different harddrive than grub, it may be necessary to trick Windows into believing that it is in fact the first harddrive. This was possible in the old grub with {{ic|map}} and is now done with {{ic|drivemap}}. Assume grub is on {{ic|hd0}} and windows on {{ic|hd2}}, you need to add the following after {{ic|set root}}:
+
If the Windows bootloader is on an entirely different hard drive than GRUB, it may be necessary to trick Windows into believing that it is the first hard drive. This was possible with {{ic|drivemap}}. Assuming GRUB is on {{ic|hd0}} and Windows is on {{ic|hd2}}, you need to add the following after {{ic|set root}}:
  
 
  drivemap -s hd0 hd2
 
  drivemap -s hd0 hd2
Line 584: Line 599:
 
  title      Chainload into GRUB v2
 
  title      Chainload into GRUB v2
 
  root        (hd0,7)
 
  root        (hd0,7)
−
  kernel      /boot/grub/core.img
+
  kernel      /boot/grub/i386-pc/core.img
  
 
===Visual Configuration===
 
===Visual Configuration===
  
−
In GRUB2 it is possible, by default, to change the look of the menu. Make sure to initialize, if not done already, grub2 graphical terminal, gfxterm, with proper video mode, gfxmode, in grub2. This can be seen in the section [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]]. This video mode is passed by grub2 to the linux kernel via 'gfxpayload' so any visual configurations need this mode in order to be in effect.
+
In GRUB2 it is possible, by default, to change the look of the menu. Make sure to initialize, if not done already, GRUB2 graphical terminal, gfxterm, with proper video mode, gfxmode, in GRUB2. This can be seen in the section [[#Correct_GRUB2_No_Suitable_Mode_Found_Error]]. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload' so any visual configurations need this mode in order to be in effect.
  
 
====Setting the framebuffer resolution ====
 
====Setting the framebuffer resolution ====
  
−
Grub2 can set the framebuffer for both grub2 itself and the kernel. The old ''vga='' way is deprecated. The preferred method is editing {{ic|/etc/default/grub}} as the following sample:
+
GRUB2 can set the framebuffer for both GRUB2 itself and the kernel. The old {{ic|1=vga=}} way is deprecated. The preferred method is editing {{ic|/etc/default/grub}} as the following sample:
  
 
  GRUB_GFXMODE=1024x768x32
 
  GRUB_GFXMODE=1024x768x32
Line 598: Line 613:
  
 
To generate the changes, run:  
 
To generate the changes, run:  
−
  grub-mkconfig -o /boot/grub/grub.cfg
+
  # grub-mkconfig -o /boot/grub/grub.cfg
  
 
The {{ic|gfxpayload}} property will make sure the kernel keeps the resolution.
 
The {{ic|gfxpayload}} property will make sure the kernel keeps the resolution.
  
 
{{Note|If this example does not work for you try to replace {{ic|1=gfxmode="1024x768x32"}} by {{ic|1=vbemode="0x105"}}. Remember to replace the specified resolution with one suitable for your screen.}}
 
{{Note|If this example does not work for you try to replace {{ic|1=gfxmode="1024x768x32"}} by {{ic|1=vbemode="0x105"}}. Remember to replace the specified resolution with one suitable for your screen.}}
−
{{Note|To show all the modes you can use {{ic|1=# hwinfo --framebuffer}} (hwinfo is available in [community]), while at grub2 prompt you can use the {{ic|1=vbeinfo}} command.}}
+
{{Note|To show all the modes you can use {{ic|1=# hwinfo --framebuffer}} (hwinfo is available in [community]), while at GRUB2 prompt you can use the {{ic|1=vbeinfo}} command.}}
  
 
If this method does not work for you, the deprecated {{ic|1=vga=}} method will still work. Just
 
If this method does not work for you, the deprecated {{ic|1=vga=}} method will still work. Just
Line 609: Line 624:
 
for eg: {{ic|1="GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vga=792"}} will give you a {{ic|1024x768}} resolution.
 
for eg: {{ic|1="GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vga=792"}} will give you a {{ic|1024x768}} resolution.
  
−
You can choose one of these resolutions: {{ic|640×480}}, {{ic|800×600}}, {{ic|1024×768}}, {{ic|1280×1024}}, {{ic|1600×1200}}
+
You can choose one of these resolutions: {{ic|640×480}}, {{ic|800×600}}, {{ic|1024×768}}, {{ic|1280×1024}}, {{ic|1600×1200}}, {{ic|1920×1200}}
 +
 
 +
====915resolution hack ====
 +
 
 +
Some times for Intel graphic adapters neither {{ic|1=# hwinfo --framebuffer}} nor {{ic|1=vbeinfo}} will show you the desired resolution. In this case you can use {{ic|915resolution}} hack. This hack will temporarily modify video BIOS and add needed resolution. See [http://915resolution.mango-lang.org/ 915resolution's home page]
 +
 
 +
In the following I will proceed with the example for my system. Please adjust the recipe for your needs. First you need to find a video mode which will be modified later. For that, run {{ic|915resolution}} in GRUB2 command shell:
 +
915resolution -l
 +
The output will be something like:
 +
Intel 800/900 Series VBIOS Hack : version 0.5.3
 +
...
 +
Mode 30 : 640x480, 8 bits/pixel
 +
...
 +
Next, our purpose is to overwrite mode 30. (You can choose what ever mode you want.) In the file {{ic|/etc/grub.d/00_header}} just before the {{ic|set gfxmode&#61;${GRUB_GFXMODE}}} line insert:
 +
915resolution 30 1440 900
 +
Here we are overwriting the mode {{ic|30}} with {{ic|1440x900}} resolution. Lastly we need to set {{ic|GRUB_GFXMODE}} as described earlier, regenerate GRUB2 configuration file and reboot to test changes:
 +
# grub-mkconfig -o /boot/grub/grub.cfg
 +
# reboot
  
 
====Background image and bitmap fonts====
 
====Background image and bitmap fonts====
  
−
GRUB2 comes with support for background images and bitmap fonts in pf2 format. The unifont font is included in the grub2 package under the filename {{ic|unicode.pf2}}, or, as only ascii characters under the name {{ic|ascii.pf2}}.  
+
GRUB2 comes with support for background images and bitmap fonts in {{ic|pf2}} format. The unifont font is included in the {{Pkg|grub-common}} package under the filename {{ic|unicode.pf2}}, or, as only ASCII characters under the name {{ic|ascii.pf2}}.
  
 
Image formats supported include tga, png and jpeg, providing the correct modules are loaded. The maximum supported resolution depends on your hardware.
 
Image formats supported include tga, png and jpeg, providing the correct modules are loaded. The maximum supported resolution depends on your hardware.
  
−
Make sure you have set up the proper [https://wiki.archlinux.org/index.php/GRUB2#Setting_the_framebuffer_resolution framebuffer resolution].
+
Make sure you have set up the proper [[#Setting the framebuffer resolution|framebuffer resolution]].
  
 
Edit {{ic|/etc/default/grub}} like this:
 
Edit {{ic|/etc/default/grub}} like this:
−
  GRUB_BACKGROUND="/boot/grub/archlinux.tga"
+
  GRUB_BACKGROUND="/boot/grub/myimage"
 
  #GRUB_THEME="/path/to/gfxtheme"
 
  #GRUB_THEME="/path/to/gfxtheme"
 +
GRUB_FONT="/path/to/font.pf2"
  
−
(archlinux.tga is a placeholder; put your file name there)
+
{{Note|If you have installed GRUB on a separate partition, {{ic|/boot/grub/myimage}} becomes {{ic|/grub/myimage}}.}}
−
 
 
−
{{Note|If you have installed Grub on a separate partition, {{ic|/boot/grub/archlinux.tga}} becomes {{ic|/grub/archlinux.tga}}.}}
 
  
−
To generate the changes and add the information into grub.cfg, run:  
+
To generate the changes and add the information into {{ic|grub.cfg}}, run:  
 
  grub-mkconfig -o /boot/grub/grub.cfg
 
  grub-mkconfig -o /boot/grub/grub.cfg
  
−
If adding the splash image was successful, the user will see "Found background image..." in the terminal as the command is executed.  
+
If adding the splash image was successful, the user will see {{ic|"Found background image..."}} in the terminal as the command is executed.  
−
If this phrase is not seen, the image information was probably not incorporated into the grub.cfg file.
+
If this phrase is not seen, the image information was probably not incorporated into the {{ic|grub.cfg}} file.
 
   
 
   
 
If the image is not displayed, check:
 
If the image is not displayed, check:
−
* The path and the filename in /etc/default/grub are correct.
+
* The path and the filename in {{ic|/etc/default/grub}} are correct.
 
* The image is of the proper size and format (tga, png, 8-bit jpg).
 
* The image is of the proper size and format (tga, png, 8-bit jpg).
 
* The image was saved in the RGB mode, and is not indexed.
 
* The image was saved in the RGB mode, and is not indexed.
−
* The console mode is not enabled in /etc/default/grub.
+
* The console mode is not enabled in {{ic|/etc/default/grub}}.
−
* The command grub-mkconfig must be executed to place the background image information into the /boot/grub/grub.cfg file.
+
* The command {{ic|grub-mkconfig}} must be executed to place the background image information into the {{ic|/boot/grub/grub.cfg}} file.
 +
 
 +
====Theme====
 +
 
 +
Here is an example for configuring Starfield theme which was included in GRUB2 package.
 +
 
 +
Edit {{ic|/etc/default/grub}}
 +
GRUB_THEME="/usr/share/grub/themes/starfield/theme.txt"
 +
 
 +
Generate the changes:
 +
grub-mkconfig -o /boot/grub/grub.cfg
 +
 
 +
If configuring the theme was successful, you'll see {{ic|Found theme: /usr/share/grub/themes/starfield/theme.txt}} in the terminal.
 +
Your splash image will usually not be displayed when using a theme.
  
 
====Menu colors====
 
====Menu colors====
  
−
As in Grub (0.9x), you can change the menu colors in Grub2. The available colors for GRUB2 are at http://www.gnu.org/software/grub/manual/html_node/Theme-file-format.html#Theme-file-format.
+
You can set the menu colors in GRUB2. The available colors for GRUB2 can be found in [https://www.gnu.org/software/grub/manual/html_node/Theme-file-format.html the GRUB Manual].
 
Here is an example:
 
Here is an example:
  
Line 654: Line 698:
 
====Hidden menu====
 
====Hidden menu====
  
−
One of the unique features of Grub2 is hiding/skipping the menu and showing it by holding "Shift" when needed. You can also adjust whether you want to see the timeout counter.
+
One of the unique features of GRUB2 is hiding/skipping the menu and showing it by holding {{keypress|Esc}} when needed. You can also adjust whether you want to see the timeout counter.
  
 
Edit {{ic|/etc/default/grub}} as you wish. Here is an example where the comments from the beginning of the two lines have been removed to enable the feature, the timeout has been set to five seconds and to be shown to the user:
 
Edit {{ic|/etc/default/grub}} as you wish. Here is an example where the comments from the beginning of the two lines have been removed to enable the feature, the timeout has been set to five seconds and to be shown to the user:
 
  GRUB_HIDDEN_TIMEOUT=5
 
  GRUB_HIDDEN_TIMEOUT=5
 
  GRUB_HIDDEN_TIMEOUT_QUIET=false
 
  GRUB_HIDDEN_TIMEOUT_QUIET=false
 +
 +
and run:
 +
# grub-mkconfig -o /boot/grub/grub.cfg
 +
 +
====Disable framebuffer====
 +
 +
Users who use NVIDIA proprietary driver might wish to disable GRUB2's framebuffer as it can cause problems with the binary driver.
 +
 +
To disable framebuffer, edit {{ic|/etc/default/grub}} and uncomment the following line:
 +
GRUB_TERMINAL_OUTPUT=console
  
 
and run:
 
and run:
Line 673: Line 727:
 
and specify your root in the menuentry as:
 
and specify your root in the menuentry as:
  
−
  set root=(''lvm_group_name''-''lvm_logical_boot_partition_name'')
+
  set root=lvm/''lvm_group_name''-''lvm_logical_boot_partition_name''
  
 
Example:
 
Example:
Line 680: Line 734:
 
  menuentry "Arch Linux" {
 
  menuentry "Arch Linux" {
 
  insmod lvm
 
  insmod lvm
−
  set root=(VolumeGroup-lv_boot)
+
  set root=lvm/VolumeGroup-lv_boot
 
  # you can only set following two lines
 
  # you can only set following two lines
 
  linux /vmlinuz-linux root=/dev/mapper/VolumeGroup-root ro
 
  linux /vmlinuz-linux root=/dev/mapper/VolumeGroup-root ro
Line 686: Line 740:
 
  }
 
  }
  
−
==== Raid ====
+
==== RAID ====
  
−
Grub2 provides convenient handling of raid-volumes. You need to add:
+
GRUB2 provides convenient handling of RAID volumes. You need to add {{ic|insmod mdraid}} which allows you to address the volume natively. For example, {{ic|/dev/md0}} becomes:
−
insmod raid
 
−
 
 
−
which allows you to address the volume natively. E.g. {{ic|/dev/md0}} becomes:
 
 
  set root=(md0)
 
  set root=(md0)
  
−
whereas a partitioned raid-volume (e.g. {{ic|/dev/md0p1}}) becomes:
+
whereas a partitioned RAID volume (e.g. {{ic|/dev/md0p1}}) becomes:
 
  set root=(md0,1)
 
  set root=(md0,1)
  
 
==== Persistent block device naming ====
 
==== Persistent block device naming ====
−
You can use UUIDs to detect partitions instead of the "old" {{ic|/dev/sd*}} and {{ic|/dev/hd*}} scheming. It has the advantage of detecting partitions by their unique UUIDs, which is needed by some people booting with complicated partition setups.
+
One naming scheme for [[Persistent block device naming]] is the use of globally unique UUIDs to detect partitions instead of the "old" {{ic|/dev/sd*}}. Advantages are covered up in the above linked article.
 +
 
 +
Persistent naming via filesystem UUIDs are used by default in GRUB2.
 +
 
 +
{{Note|The {{ic|/boot/grub.cfg}} file needs regeneration with the new UUID in {{ic|/etc/default/grub}} every time a relevant filesystem is resized or recreated. Remember this when modifying partitions & filesystems with a Live-CD.}}
  
−
UUIDs are used by default in the recent versions of grub2 - there is no downside in it anyway except that you need to re-generate the {{ic|grub.cfg}} file every time you resize or reformat your partitions. Remember this when modifying partitions with Live-CD.
+
Whether to use UUIDs is controlled by an option in /etc/default/grub:
  
−
The recent versions of grub2 use UUIDs by default. You can re-enable the use of UUIDS by simply commenting the UUID line (this is also what it looks like by default):
+
{{bc|1=# GRUB_DISABLE_LINUX_UUID=true}}
−
#GRUB_DISABLE_LINUX_UUID=true
 
−
you can also just set the value as {{ic|false}} as shown here:
 
−
GRUB_DISABLE_LINUX_UUID=false
 
  
 
Either way, do not forget to generate the changes:
 
Either way, do not forget to generate the changes:
−
grub-mkconfig -o /boot/grub/grub.cfg
+
{{bc|# grub-mkconfig -o /boot/grub/grub.cfg}}
  
 
==== Using Labels ====
 
==== Using Labels ====
  
 
It is possible to use labels, human-readable strings attached to filesystems, by using the {{ic|--label}} option to {{ic|search}}. First of all, label your existing partition:
 
It is possible to use labels, human-readable strings attached to filesystems, by using the {{ic|--label}} option to {{ic|search}}. First of all, label your existing partition:
−
  # tune2fs -L a <LABEL> <PARTITION>
+
  # tune2fs -L <LABEL> <PARTITION>
  
 
Then, add an entry using labels. An example of this:
 
Then, add an entry using labels. An example of this:
  
 
  menuentry "Arch Linux, session texte" {
 
  menuentry "Arch Linux, session texte" {
−
     search --label --no-floppy --set=root archroot
+
     search --label --set=root archroot
 
     linux /boot/vmlinuz-linux root=/dev/disk/by-label/archroot ro
 
     linux /boot/vmlinuz-linux root=/dev/disk/by-label/archroot ro
 
     initrd /boot/initramfs-linux.img
 
     initrd /boot/initramfs-linux.img
Line 725: Line 777:
 
==== Recall previous entry ====
 
==== Recall previous entry ====
  
−
Grub2 can remember the last entry you booted from and use this as the default entry to boot from next time. This is useful if you have multiple kernels (i.e., the current Arch one and the LTS kernel as a fallback option) or operating systems. To do this, edit {{ic|/etc/default/grub}} and change the setting of {{ic|GRUB_DEFAULT}}:
+
GRUB2 can remember the last entry you booted from and use this as the default entry to boot from next time. This is useful if you have multiple kernels (i.e., the current Arch one and the LTS kernel as a fallback option) or operating systems. To do this, edit {{ic|/etc/default/grub}} and change the setting of {{ic|GRUB_DEFAULT}}:
  
 
  GRUB_DEFAULT=saved
 
  GRUB_DEFAULT=saved
  
−
This ensures that grub will default to the saved entry. To enable saving the selected entry, add the following line to {{ic|/etc/default/grub}}:
+
This ensures that GRUB will default to the saved entry. To enable saving the selected entry, add the following line to {{ic|/etc/default/grub}}:
  
 
  GRUB_SAVEDEFAULT=true
 
  GRUB_SAVEDEFAULT=true
  
−
Note that manually added menu items, eg Windows in {{ic|/etc/grub.d/40_custom}}, will need {{ic|savedefault}} added. Remember to regenerate your configuration file.
+
{{Note|Manually added menu items, eg Windows in {{ic|/etc/grub.d/40_custom}} or {{ic|/boot/grub/custom.cfg}} , will need {{ic|savedefault}} added. Remember to regenerate your configuration file.}}
  
 
==== Security ====
 
==== Security ====
  
−
If you want to secure GRUB2 so it is not possible for anyone to change boot parameters or use the command line, you can add a user/password combination to GRUB2's configuration files. To do this, run the command {{ic|grub-mkpasswd_pbkdf2}}. Enter a password and confirm it. The output will look like this:
+
If you want to secure GRUB2 so it is not possible for anyone to change boot parameters or use the command line, you can add a user/password combination to GRUB2's configuration files. To do this, run the command {{ic|grub-mkpasswd-pbkdf2}}. Enter a password and confirm it. The output will look like this:
  
 
{{bc|<nowiki>
 
{{bc|<nowiki>
Line 747: Line 799:
  
 
EOF</nowiki>}}
 
EOF</nowiki>}}
−
where <password> is the string generated by {{ic|grub-mkpasswd_pbkdf2}}.
+
where {{ic|<password>}} is the string generated by {{ic|grub-mkpasswd_pbkdf2}}.
  
−
Regenerate your configuration file. Your GRUB2 command line and boot parameters are now protected.
+
Regenerate your configuration file. Your GRUB2 command line, boot parameters and all boot entries are now protected.
  
−
=== Booting an Ubuntu ISO Image from the GRUB2 Screen ===
+
This can be relaxed and further customized with more users as described in the "Security" part of [https://www.gnu.org/software/grub/manual/grub.html#Security the GRUB manual].
  
−
Edit {{ic|/etc/grub.d/40_custom}} to add an entry pointing to an Ubuntu iso:
+
==== Root Encryption ====
  
−
  menuentry "ubuntu-11.04-desktop-amd64.iso" {
+
To let GRUB2 automatically add the kernel parameters for root encryption,
−
set isofile="/path/to/ubuntu-11.04-desktop-amd64.iso"
+
add {{ic|1=cryptdevice=/dev/yourdevice:label}} to {{ic|GRUB_CMDLINE_LINUX}} in {{ic|/etc/default/grub}}.
−
loopback loop (hdX,Y)$isofile
+
 
−
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet noeject noprompt splash --
+
Example with root mapped to {{ic|/dev/mapper/root}}:
−
initrd (loop)/casper/initrd.lz
+
 
 +
GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda2:root"
 +
 
 +
Also, disable the usage of UUIDs for the rootfs:
 +
 
 +
GRUB_DISABLE_LINUX_UUID=true
 +
 
 +
Regenerate the configuration.
 +
 
 +
==== Boot non-default entry only once ====
 +
 
 +
The command {{ic|grub-reboot}} is very helpful to boot another entry than the default only once. GRUB2 loads the entry passed in the first command line argument, when the system is rebooted the next time. Most importantly GRUB2 returns to loading the default entry for all future booting. Changing the configuration file or selecting an entry in the GRUB2 menu is not necessary.
 +
 
 +
=== Booting an ISO Directly From GRUB2 ===
 +
Edit {{ic|/etc/grub.d/40_custom}} or {{ic|/boot/grub/custom.cfg}} to add an entry for the target ISO. When finished, update the GRUB menu as with the usual {{ic|grub-mkconfig -o /boot/grub/grub.cfg}} (as root).
 +
 
 +
==== Arch ISO ====
 +
{{Note|The example assumes that the iso is in {{ic|/archives}} on {{ic|hd0,6}}. Users must adjust the location and hdd/partition in ALL of the lines below to match their systems. However, if booting the ISO from USB on a computer which also has one internal HDD, then it needs to be {{ic|hd0,Y}} with {{ic|sdbY}}, instead of {{ic|sdaY}}.}}
 +
 
 +
'''Example using x86_64'''
 +
  menuentry "Archlinux-2013.01.04-dual.iso" --class iso {
 +
  set isofile="/archives/archlinux-2013.01.04-dual.iso"
 +
  loopback loop (hd0,6)$isofile
 +
  linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=ARCH_201301 img_dev=/dev/sda6 img_loop=$isofile earlymodules=loop
 +
  initrd (loop)/arch/boot/x86_64/archiso.img
 
  }
 
  }
  
−
Be sure to adjust the "hdX,Y" in the third line to point to the correct disk/partition number of the isofile.  When finished, update grub2's configuration file via:
+
'''Example using i686'''
 +
menuentry "Archlinux-2013.01.04-dual.iso" --class iso {
 +
  set isofile="/archives/archlinux-2013.01.04-dual.iso"
 +
  loopback loop (hd0,6)$isofile
 +
  linux (loop)/arch/boot/i686/vmlinuz archisolabel=ARCH_201301 img_dev=/dev/sda6 img_loop=$isofile earlymodules=loop
 +
  initrd (loop)/arch/boot/i686/archiso.img
 +
  }
  
−
  grub-mkconfig -o /boot/grub/grub.cfg
+
{{Tip|For thumbdrives, use [[Persistent_block_device_naming|Persistent block device names]] for the "img_dev" kernel parameter. '''Ex:''' img_dev&#61;/dev/disk/by-label/CORSAIR}}
 +
 
 +
==== Ubuntu ISO ====
 +
{{Note|The example assumes that the iso is in {{ic|/archives}} on {{ic|hd0,6}}. Users must adjust the location and hdd/partition in the lines below to match their systems.}}
 +
 
 +
  menuentry "ubuntu-12.04-desktop-amd64.iso" {
 +
    set isofile="/archives/ubuntu-12.04-desktop-amd64.iso"
 +
    loopback loop (hd0,6)$isofile
 +
    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet noeject noprompt splash --
 +
    initrd (loop)/casper/initrd.lz
 +
}
 +
 
 +
==== Other ISOs ====
 +
 
 +
Other working configurations from [http://askubuntu.com/questions/141940/how-to-boot-live-iso-images link Source].
  
 
== Using the command shell ==
 
== Using the command shell ==
Line 778: Line 874:
 
The rescue shell is a restricted subset of the normal shell, offering much less functionality. If dumped to the rescue shell, first try inserting the "normal" module, then starting the "normal" shell:
 
The rescue shell is a restricted subset of the normal shell, offering much less functionality. If dumped to the rescue shell, first try inserting the "normal" module, then starting the "normal" shell:
 
  grub rescue> set prefix=(hdX,Y)/boot/grub
 
  grub rescue> set prefix=(hdX,Y)/boot/grub
−
  grub rescue> insmod (hdX,Y)/boot/grub/normal.mod
+
  grub rescue> insmod (hdX,Y)/boot/grub/i386-pc/normal.mod
 
  rescue:grub> normal
 
  rescue:grub> normal
  
Line 789: Line 885:
  
 
Following package may be installed from [[AUR]]
 
Following package may be installed from [[AUR]]
−
* [http://kde-apps.org/content/show.php?content=139643 grub2-editor] (requires kdelibs)
+
* {{aur|grub-customizer}} (requires gettext gksu gtkmm hicolor-icon-theme openssl)
 +
*:Customize the bootloader (GRUB2 or BURG)
 +
* {{aur|grub2-editor}} (requires kdelibs)
 
*:A KDE4 control module for configuring the GRUB2 bootloader
 
*:A KDE4 control module for configuring the GRUB2 bootloader
−
* [http://kde-apps.org/content/show.php?content=137886 kcm-grub2] (requires kdelibs python2-qt kdebindings-python)
+
* {{aur|kcm-grub2}} (requires kdelibs python2-qt kdebindings-python)
 
*:This Kcm module manages the most common settings of Grub2.
 
*:This Kcm module manages the most common settings of Grub2.
−
* [http://sourceforge.net/projects/startup-manager/ startupmanager] (requires gnome-python imagemagick yelp python2 xorg-xrandr)
+
* {{aur|startupmanager}} (requires gnome-python imagemagick yelp python2 xorg-xrandr)
 
*:GUI app for changing the settings of GRUB, GRUB2, Usplash and Splashy
 
*:GUI app for changing the settings of GRUB, GRUB2, Usplash and Splashy
  
−
== parttool or legacy hide/unhide ==
+
== parttool for hide/unhide ==
  
−
If you have a win9x paradigm with hidden C disks GRUB legacy had the hide/unhide feature. In GRUB2 this has been replaced by parttool. For example, to boot the third C disk of three win9x installations on the CLI enter the CLI and:
+
If you have a Windows 9x paradigm with hidden C:\ disks GRUB can hide/unhide it using {{ic|parttool}}. For example, to boot the third C:\ disk of three Windows 9x installations on the CLI enter the CLI and:
 
  parttool hd0,1 hidden+ boot-
 
  parttool hd0,1 hidden+ boot-
 
  parttool hd0,2 hidden+ boot-
 
  parttool hd0,2 hidden+ boot-
Line 810: Line 908:
 
See [[#Using the command shell]] first. If unable to activate the standard shell, one possible solution is to boot using a live CD or some other rescue disk to correct configuration errors and reinstall GRUB. However, such a boot disk is not always available (nor necessary); the rescue console is surprisingly robust.
 
See [[#Using the command shell]] first. If unable to activate the standard shell, one possible solution is to boot using a live CD or some other rescue disk to correct configuration errors and reinstall GRUB. However, such a boot disk is not always available (nor necessary); the rescue console is surprisingly robust.
  
−
The available commands in GRUB rescue include "insmod", "ls", "set", and "unset". This example uses "set" and "insmod". "set" modifies variables and "insmod" inserts new modules to add functionality.
+
The available commands in GRUB rescue include {{ic|insmod}}, {{ic|ls}}, {{ic|set}}, and {{ic|unset}}. This example uses {{ic|set}} and {{ic|insmod}}. {{ic|set}} modifies variables and {{ic|insmod}} inserts new modules to add functionality.
  
 
Before starting, the user must know the location of their {{ic|/boot}} partition (be it a separate partition, or a subdirectory under their root):
 
Before starting, the user must know the location of their {{ic|/boot}} partition (be it a separate partition, or a subdirectory under their root):
Line 817: Line 915:
 
where X is the physical drive number and Y is the partition number.
 
where X is the physical drive number and Y is the partition number.
  
−
To expand console capabilities, insert the "linux" module:
+
To expand console capabilities, insert the {{ic|linux}} module:
 
  grub rescue> insmod (hdX,Y)/boot/grub/linux.mod
 
  grub rescue> insmod (hdX,Y)/boot/grub/linux.mod
  
 
{{Note|With a separate boot partition, omit {{ic|/boot}} from the path, (i.e. type {{ic|1=set prefix=(hdX,Y)/grub}} and {{ic|insmod (hdX,Y)/grub/linux.mod}}).}}
 
{{Note|With a separate boot partition, omit {{ic|/boot}} from the path, (i.e. type {{ic|1=set prefix=(hdX,Y)/grub}} and {{ic|insmod (hdX,Y)/grub/linux.mod}}).}}
  
−
This introduces the "linux" and "initrd" commands, which should be familiar (see [[#Configuration]]).
+
This introduces the {{ic|linux}} and {{ic|initrd}} commands, which should be familiar (see [[#Configuration]]).
  
 
An example, booting Arch Linux:
 
An example, booting Arch Linux:
Line 836: Line 934:
 
  boot
 
  boot
  
−
After successfully booting the Arch Linux installation, users can correct {{ic|grub.cfg}} as needed and then run:
+
After successfully booting the Arch Linux installation, users can correct {{ic|grub.cfg}} as needed and then reinstall GRUB2.
−
# grub-install /dev/sda --no-floppy
 
  
 
to reinstall GRUB2 and fix the problem completely, changing {{ic|/dev/sda}} if needed. See [[#Bootloader installation]] for details.
 
to reinstall GRUB2 and fix the problem completely, changing {{ic|/dev/sda}} if needed. See [[#Bootloader installation]] for details.
  
−
== Combining the use of UUID's and basic scripting ==
+
== Combining the use of UUIDs and basic scripting ==
  
−
If you like the idea of using UUID's to avoid unreliable BIOS mappings or are struggling with Grub's syntax, here is an example boot menu item that uses UUID's and a small script to direct Grub to the proper disk partitions for your system. All you need to do is replace the UUID's in the sample with the correct UUID's for your system. (The example applies to a system with a boot and root partition. You will obviously need to modify the Grub configuration if you have additional partitions.)
+
If you like the idea of using UUIDs to avoid unreliable BIOS mappings or are struggling with GRUB's syntax, here is an example boot menu item that uses UUIDs and a small script to direct GRUB to the proper disk partitions for your system. All you need to do is replace the UUIDs in the sample with the correct UUIDs for your system. The example applies to a system with a boot and root partition. You will obviously need to modify the GRUB configuration if you have additional partitions:
  
 
   menuentry "Arch Linux 64" {
 
   menuentry "Arch Linux 64" {
−
    #Enter the UUID of your boot partition (this is where Grub and your kernel reside)
+
      # Set the UUIDs for your boot and root partition respectively
−
    set uuid_grub_boot=ece0448f-bb08-486d-9864-ac3271bd8d07
+
      set the_boot_uuid=ece0448f-bb08-486d-9864-ac3271bd8d07
 +
      set the_root_uuid=c55da16f-e2af-4603-9e0b-03f5f565ec4a
 
      
 
      
−
    #Enter the UUID of the partition containing the root partition of your Arch Linux installation.           
+
      # (Note: This may be the same as your boot partition)
−
    set uuid_os_root=c55da16f-e2af-4603-9e0b-03f5f565ec4a
 
 
      
 
      
−
    #(Note: this may be the same as your boot partition)
+
      # Get the boot/root devices and set them in the root and grub_boot variables
 +
      search --fs-uuid --set=root $the_root_uuid
 +
      search --fs-uuid --set=grub_boot $the_boot_uuid
 
      
 
      
−
    #Here we set the Grub "root" variable by locating the UUID of the root partition identified above 
+
      # Check to see if boot and root are equal.
−
    search --fs-uuid --no-floppy --set=root $uuid_os_root
+
      # If they are, then append /boot to $grub_boot (Since $grub_boot is actually the root partition)
 +
      if [ $the_boot_uuid == $the_root_uuid] ; then
 +
          set grub_boot=$grub_boot/boot
 +
      fi
 
      
 
      
−
    #Here we set a custom variable grub_boot by locating the UUID of the boot partition identified above         
+
      # $grub_boot now points to the correct location, so the following will properly find the kernel and initrd
−
    search --fs-uuid --no-floppy --set=grub_boot $uuid_grub_boot
+
      linux ($grub_boot)/vmlinuz-linux root=/dev/disk/by-uuid/$uuid_os_root ro
−
   
+
      initrd ($grub_boot)/initramfs-linux.img
−
    #Here is the magic. We test to see if the boot and root partitions have the same UUID.
 
−
    #If they do, we append /boot to the $grub_boot variable. For ex. (hd0,1) becomes (hd0,1)/boot.
 
−
    if [ $uuid_grub_boot == $uuid_os_root ] ; then
 
−
      set grub_boot=$grub_boot/boot
 
−
    fi
 
−
   
 
−
    # $grub_boot now points to the correct location, so the following will properly find the kernel and initrd
 
−
    linux ($grub_boot)/vmlinuz-linux root=/dev/disk/by-uuid/$uuid_os_root ro
 
−
    initrd ($grub_boot)/initramfs-linux.img
 
 
   }
 
   }
  
Line 877: Line 970:
 
=== Enable GRUB2 debug messages ===
 
=== Enable GRUB2 debug messages ===
  
−
Add
+
Add:
 
   
 
   
 
  set pager=1
 
  set pager=1
Line 886: Line 979:
 
=== Correct GRUB2 No Suitable Mode Found Error ===
 
=== Correct GRUB2 No Suitable Mode Found Error ===
  
−
If you get this error when booting any menuentry
+
If you get this error when booting any menuentry:
  
 
  error: no suitable mode found
 
  error: no suitable mode found
 
  Booting however
 
  Booting however
  
−
Then you need to initialize grub2 graphical terminal (gfxterm) with proper video mode (gfxmode) in grub2. This video mode is passed by grub2 to the linux kernel via 'gfxpayload'. In case of UEFI systems, if the grub2 video mode is not initialized, no kernel boot messages will be shown in the terminal (atleast until KMS kicks in)
+
Then you need to initialize GRUB2 graphical terminal ({{ic|gfxterm}}) with proper video mode ({{ic|gfxmode}}) in GRUB2. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload'. In case of UEFI systems, if the GRUB2 video mode is not initialized, no kernel boot messages will be shown in the terminal (atleast until KMS kicks in).
  
−
Copy {{ic|/usr/share/grub/unicode.pf2}} to ${GRUB2_PREFIX_DIR} ({{ic|/boot/grub/}} in case of BIOS systems and {{ic|/boot/efi/efi/grub/}} in case of UEFI systems).
+
Copy {{ic|/usr/share/grub/unicode.pf2}} to ${GRUB2_PREFIX_DIR} ({{ic|/boot/grub/}} in case of BIOS and UEFI systems). If GRUB2 UEFI was installed with {{ic|1=--boot-directory=/boot/efi/EFI}} set, then the directory is {{ic|/boot/efi/EFI/grub/}}:
  
 
  # cp /usr/share/grub/unicode.pf2 ${GRUB2_PREFIX_DIR}
 
  # cp /usr/share/grub/unicode.pf2 ${GRUB2_PREFIX_DIR}
  
−
If {{ic|/usr/share/grub/unicode.pf2}} does not exist, install {{Pkg|bdf-unifont}}, create the unifont.pf2 file and then copy it to ${GRUB2_PREFIX_DIR}.
+
If {{ic|/usr/share/grub/unicode.pf2}} does not exist, install {{Pkg|bdf-unifont}}, create the {{ic|unifont.pf2}} file and then copy it to {{ic|${GRUB2_PREFIX_DIR<nowiki>}</nowiki>}}:
  
 
  # grub-mkfont -o unicode.pf2 /usr/share/fonts/misc/unifont.bdf
 
  # grub-mkfont -o unicode.pf2 /usr/share/fonts/misc/unifont.bdf
  
−
Then, in the {{ic|grub.cfg}} file, add the following lines to enable grub2 to pass the video mode correctly to the kernel, without of which you will only get a black screen (no output) but booting (actually) proceeds successfully without any system hang:
+
Then, in the {{ic|grub.cfg}} file, add the following lines to enable GRUB2 to pass the video mode correctly to the kernel, without of which you will only get a black screen (no output) but booting (actually) proceeds successfully without any system hang.
  
−
BIOS systems
+
BIOS systems:
  
 
  insmod vbe
 
  insmod vbe
  
−
UEFI systems
+
UEFI systems:
  
 
  insmod efi_gop
 
  insmod efi_gop
 
  insmod efi_uga
 
  insmod efi_uga
  
−
After that add the following code (common to both BIOS and UEFI)
+
After that add the following code (common to both BIOS and UEFI):
  
 
  insmod font
 
  insmod font
  
−
  if loadfont ${prefix}/unicode.pf2
+
  if loadfont ${prefix}/fonts/unicode.pf2
 
  then
 
  then
 
     insmod gfxterm
 
     insmod gfxterm
Line 924: Line 1,017:
 
  fi
 
  fi
  
−
As you can see for gfxterm (graphical terminal) to function properly, {{ic|unicode.pf2}} font file should exist in ${GRUB2_PREFIX_DIR}.
+
As you can see for gfxterm (graphical terminal) to function properly, {{ic|unicode.pf2}} font file should exist in {{ic|${GRUB2_PREFIX_DIR<nowiki>}</nowiki>}}.
  
 
=== msdos-style error message ===
 
=== msdos-style error message ===
Line 933: Line 1,026:
 
  grub-setup: error: If you really want blocklists, use --force.
 
  grub-setup: error: If you really want blocklists, use --force.
  
−
This error may occur when you try installing GRUB2 in a VMware container. Read more about it [http://bbs.archlinux.org/viewtopic.php?pid=581760#p581760 here]. It happens when the first partition starts just after the MBR (block 63), without the usual space of 1 MiB (2048 blocks) before the first partition. Read [[#MBR_aka_msdos_partitioning_specific_instructions]]
+
This error may occur when you try installing GRUB2 in a VMware container. Read more about it [https://bbs.archlinux.org/viewtopic.php?pid=581760#p581760 here]. It happens when the first partition starts just after the MBR (block 63), without the usual space of 1 MiB (2048 blocks) before the first partition. Read [[#Master Boot Record (MBR) specific instructions]]
  
 
=== UEFI GRUB2 drops to shell ===
 
=== UEFI GRUB2 drops to shell ===
  
−
If grub loads but drop you into the rescue shell with no errors, it may be because of a missing or misplaced {{ic|grub.cfg}}. For UEFI, {{ic|grub.cfg}} must be copied into the UEFI system partition alongside grub.efi ({{ic|/boot/efi/EFI/grub}})
+
If GRUB loads but drops you into the rescue shell with no errors, it may be because of a missing or misplaced {{ic|grub.cfg}}. This will happen if GRUB2 UEFI was installed with {{ic|--boot-directory}} and {{ic|grub.cfg}} is missing OR if the partition number of the boot partition changed (which is hard-coded into the {{ic|grubx64.efi}} file).
  
 
=== UEFI GRUB2 not loaded ===
 
=== UEFI GRUB2 not loaded ===
−
In some cases the EFI may fail to load grub correctly. Provided everything is set up correctly, the output of
+
In some cases the EFI may fail to load GRUB correctly. Provided everything is set up correctly, the output of:
 
  efibootmgr -v
 
  efibootmgr -v
 
might look something like this:
 
might look something like this:
Line 948: Line 1,041:
 
  Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\efi\grub\grub.efi)
 
  Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\efi\grub\grub.efi)
 
  Boot0001* Shell HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\EfiShell.efi)
 
  Boot0001* Shell HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\EfiShell.efi)
−
  Boot0002* Festplatte BIOS(2,0,00)P0: SAMSUNG HD204UI           .
+
  Boot0002* Festplatte BIOS(2,0,00)P0: SAMSUNG HD204UI
−
If everything works correctly, the EFI would now automatically load grub.<br>
+
If everything works correctly, the EFI would now automatically load GRUB.
−
If the screen only goes black for a second and the next boot option is tried afterwards, according to [https://bbs.archlinux.org/viewtopic.php?pid=981560#p981560 this post], moving grub to the partition root can help. The boot option has to be deleted and recreated afterwards. The entry for grub should look like this then:
+
 
 +
If the screen only goes black for a second and the next boot option is tried afterwards, according to [https://bbs.archlinux.org/viewtopic.php?pid=981560#p981560 this post], moving GRUB to the partition root can help. The boot option has to be deleted and recreated afterwards. The entry for GRUB should look like this then:
 
  Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\grub.efi)
 
  Boot0000* Grub HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\grub.efi)
  
 
=== Invalid signature ===
 
=== Invalid signature ===
−
If trying to boot windows results in an "invalid signature" error, e.g. after reconfiguring partitions or adding additional hard drives, (re)move grub's device configuration and let it reconfigure.
+
If trying to boot Windows results in an "invalid signature" error, e.g. after reconfiguring partitions or adding additional hard drives, (re)move GRUB's device configuration and let it reconfigure:
 
  # mv /boot/grub/device.map /boot/grub/device.map-old
 
  # mv /boot/grub/device.map /boot/grub/device.map-old
 
  # grub-mkconfig -o /boot/grub/grub.cfg
 
  # grub-mkconfig -o /boot/grub/grub.cfg
−
Grub-mkconfig should now mention all found boot options including windows. If it works, remove /boot/grub/device.map-old.
+
{{ic|grub-mkconfig}} should now mention all found boot options, including Windows. If it works, remove {{ic|/boot/grub/device.map-old}}.
 +
 
 +
=== Boot freezes ===
 +
If booting gets stuck without any error message after grub2 loading the kernel and the initial ramdisk, try removing the {{ic|add_efi_memmap}} kernel parameter.
 +
 
 +
=== Restore GRUB Legacy ===
 +
 
 +
* Move GRUB2 files out of the way:
 +
 
 +
# mv /boot/grub /boot/grub.nonfunctional
 +
 
 +
* Copy GRUB Legacy back to {{ic|/boot}}:
 +
 
 +
# cp -af /boot/grub-legacy /boot/grub
 +
 
 +
* Replace MBR and next 62 sectors of sda with backed up copy
 +
 
 +
{{Warning|This command also restores the partition table, so be careful of overwriting a modified partition table with the old one. It '''will''' mess up your system.}}
 +
 
 +
# dd if=/path/to/backup/first-sectors of=/dev/sdX bs=512 count=1
 +
 
 +
A safer way is to restore only the MBR boot code use:
 +
 
 +
# dd if=/path/to/backup/mbr-boot-code of=/dev/sdX bs=446 count=1
  
 
== References ==
 
== References ==
  
−
# Official GRUB2 Manual - http://www.gnu.org/software/grub/manual/grub.html
+
# Official GRUB2 Manual - https://www.gnu.org/software/grub/manual/grub.html
−
# Ubuntu wiki page for Grub2 - https://help.ubuntu.com/community/Grub2
+
# Ubuntu wiki page for GRUB2 - https://help.ubuntu.com/community/Grub2
 
# GRUB2 wiki page describing steps to compile for UEFI systems - https://help.ubuntu.com/community/UEFIBooting
 
# GRUB2 wiki page describing steps to compile for UEFI systems - https://help.ubuntu.com/community/UEFIBooting
−
# Wikipedia's page on [http://en.wikipedia.org/wiki/BIOS_Boot_partition BIOS Boot Partition]
+
# Wikipedia's page on [[Wikipedia:BIOS Boot partition|BIOS Boot partition]]
  
 
== External Links ==
 
== External Links ==
  
−
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub2/grub2_bios.sh A Linux Bash Shell script to compile and install GRUB2 for BIOS from BZR Source]
+
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub/grub_bios.sh A Linux Bash Shell script to compile and install GRUB(2) for BIOS from BZR Source]
−
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub2/grub2_uefi.sh A Linux Bash Shell script to compile and install GRUB2 for UEFI from BZR Source]
+
# [https://github.com/the-ridikulus-rat/My_Shell_Scripts/blob/master/grub/grub_uefi.sh A Linux Bash Shell script to compile and install GRUB(2) for UEFI from BZR Source]

Revision as of 16:03, 10 April 2013

zh-CN:GRUB2 zh-TW:GRUB2 Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary text Template:Article summary heading Template:Article summary wiki - BURG is a brand-new boot loader based on GRUB2. It can be built on a wider range of OS, and has a highly configurable menu system which works in both text and graphic mode. Template:Article summary wiki - previous Version, now obsolete. Template:Article summary heading Template:Article summary wiki Template:Article summary link Template:Article summary end GRUB2 is the next generation of the GRand Unified Bootloader (GRUB). GRUB2 is derived from PUPA which was a research project to investigate the next generation of GRUB. GRUB2 has been rewritten from scratch to clean up everything and provide modularity and portability [1].

In brief, the bootloader is the first software program that runs when a computer starts. It is responsible for loading and transferring control to the Linux kernel. The kernel, in turn, initializes the rest of the operating system.

Contents

Preface

Here is some information that needs to be clarified:

  • The name GRUB officially refers to version 2 of the software, see [2]. If you are looking for the article on the legacy version, see GRUB Legacy.
  • From 1.99-6 onwards, GRUB2 supports Btrfs as root (without a separate /boot filesystem) compressed with either zlib or LZO.

Notes for current GRUB Legacy users

  • Upgrade from GRUB Legacy to GRUB2 is the much same as fresh installing GRUB2 which is covered below.
  • There are differences in the commands of GRUB and GRUB2. Familiarize yourself with GRUB2 commands before proceeding (e.g. "find" has been replaced with "search").
  • GRUB2 is now modular and no longer requires "stage 1.5". As a result, the bootloader itself is limited -- modules are loaded from the hard drive as needed to expand functionality (e.g. for LVM or RAID support).
  • Device naming has changed between GRUB and GRUB2. Partitions are numbered from 1 instead of 0 while drives are still numbered from 0, and prefixed with partition-table type. For example, /dev/sda1 would be referred to as (hd0,msdos1) (for MBR) or (hd0,gpt1) (for GPT) using GRUB2.

Preliminary Requirements for GRUB2

BIOS systems

GUID Partition Table (GPT) specific instructions

GRUB2 in BIOS-GPT configuration requires a BIOS Boot Partition to embed its core.img in the absence of post-MBR gap in GPT partitioned systems (which is taken over by the GPT Primary Header and Primary Partition table). This partition is used by GRUB2 only in BIOS-GPT setups. No such partition type exists in case of MBR partitioning (at least not for GRUB2). This partition is also not required if the system is UEFI based, as no embedding of bootsectors takes place in that case. Syslinux does not require this partition.

For a BIOS-GPT configuration, create a 1007 KiB partition at the beginning of the disk using cgdisk or GNU Parted with no filesystem. The size of 1007 KiB will allow for the following partition to be correctly alligned at 1024 KiB. If needed, the partition can also be located somewhere else on the disk, but it should be within the first 2 TiB region. Set the partition type to 0xEF02 in gdisk, EF02 in cgdisk or set <BOOT_PART_NUM> bios_grub on in GNU Parted.

Note: This partition should be created before grub-install or grub-setup is run.
Note: gdisk will only allow you to create this partition on the position which will waste the least amount of space (sector 34-2047) if you create it last, after all the other partitions. This is because gdisk will auto-align partitions to 2048-sector boundaries if possible.
Master Boot Record (MBR) specific instructions

Usually the post-MBR gap (after the 512 byte MBR region and before the start of the 1st partition) in many MBR (or msdos disklabel) partitioned systems is 31 KiB when DOS compatibility cylinder alignment issues are satisfied in the partition table. However a post-MBR gap of about 1 to 2 MiB is recommended to provide sufficient room for embedding GRUB2's core.img (FS#24103). It is advisable to use a partitioner which supports 1 MiB partition alignment to obtain this space as well as satisfy other non-512 byte sector issues (which are unrelated to embedding of core.img).

MBR partitioning has better support in other operating systems, such as Microsoft Windows (up to Windows 7) and Haiku, than GPT partitioning. If you dual boot another operating system, consider using MBR partitioning.

A MBR disk may be convertible to GPT if there is a small amount of extra space available. See GUID Partition Table#Convert from MBR to GPT

UEFI systems

Note: It is recommended to read and understand the UEFI, GPT and UEFI Bootloaders pages.
Create and Mount the UEFI System Partition

Follow Unified Extensible Firmware Interface#EFI System Partition for instructions on creating a UEFI SYSTEM PARTITION. Then mount the UEFI SYSTEM PARTITION at /boot/efi. If you have mounted the UEFISYS partition in some other mountpoint, replace /boot/efi in the below instructions with that mountpoint: 

# mkdir -p /boot/efi
# mount -t vfat <UEFISYS_PART_DEVICE> /boot/efi

Create a <UEFI_SYSTEM_PARTITION>/EFI directory, if it does not exist: 

# mkdir -p /boot/efi/EFI

Installation

BIOS systems

Backup Important Data

Although a GRUB(2) installation should run smoothly, it is strongly recommended to keep the GRUB Legacy files before installing grub-bios. 

# mv /boot/grub /boot/grub-legacy

Backup the MBR which contains the boot code and partition table (Replace /dev/sdX with your actual disk path) 

# dd if=/dev/sdX of=/path/to/backup/mbr_backup bs=512 count=1

Only 446 bytes of the MBR contain boot code, the next 64 contain the partition table. If you do not want to overwrite your partition table when restoring, it is strongly advised to backup only the MBR boot code: 

# dd if=/dev/sdX of=/path/to/backup/bootcode_backup bs=446 count=1

If unable to install GRUB2 correctly, see #Restore GRUB Legacy.

Install grub-bios package

The GRUB(2) packages can be installed with pacman (and will replace grub-legacy or grub, if it is installed): 

# pacman -S grub-bios
Note: Simply installing the package won't update the /boot/grub/i386-pc/core.img file and the GRUB(2) modules in /boot/grub/i386-pc. You need to update them manually using grub-install as explained below.

Install grub-bios boot files

There are 3 ways to install GRUB(2) boot files in BIOS booting:

Note: See http://www.gnu.org/software/grub/manual/html_node/BIOS-installation.html for additional documentation.
Install to 440-byte MBR boot code region

To setup grub-bios in the 440-byte Master Boot Record boot code region, populate the /boot/grub directory, generate the /boot/grub/i386-pc/core.img file, embed it in the 31 KiB (minimum size - varies depending on partition alignment) post-MBR gap, and generate the configuration file, run: 

# modprobe dm-mod
# grub-install --recheck /dev/sda
# grub-mkconfig -o /boot/grub/grub.cfg

where /dev/sda is the destination of the installation (in this case the MBR of the first SATA disk). If you use LVM for your /boot, you can install GRUB2 on multiple physical disks.

Note: --no-floppy has been removed from grub-install in 2.00~beta2 upstream release, and replaced with --allow-floppy.
Warning: Make sure to check the /boot directory if you use the latter. Sometimes the boot-directory parameter creates another /boot folder inside of /boot. A wrong install would look like: /boot/boot/grub/.
Install to GPT BIOS Boot Partition

GUID Partition Table disks do not have a reserved "boot track". Therefore you must create a BIOS Boot Partition (0xEF02) to hold the GRUB core image.

Using GNU Parted, you can set this using a command such as the following: 

# parted /dev/disk set <partition-number> bios_grub on

If you are using gdisk, set the partition type to Template:Keypress. With partitioning programs that require setting the GUID directly, it should be ‘21686148-6449-6e6f-744e656564454649’ (stored on disk as "Hah!IdontNeedEFI" if interpreted as ASCII).

Warning: Be very careful which partition you select when marking it as a BIOS Boot Partition. When GRUB finds a BIOS Boot Partition during installation, it will automatically overwrite part of it. Make sure that the partition does not contain any other data.

To setup grub-bios on a GPT disk, populate the /boot/grub directory, generate the /boot/grub/i386-pc/core.img file, and embed it in the BIOS Boot Partition, run: 

# modprobe dm-mod
# grub-install --target=i386-pc --recheck --debug /dev/sda
# mkdir -p /boot/grub/locale
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo

where /dev/sda is the destination of the installation.

Install to Partition or Partitionless Disk
Note: grub-bios (any version - including upstream Bazaar repo) does not encourage installation to a partition boot sector or a partitionless disk like GRUB Legacy or Syslinux does. This kind of setup is prone to breakage, especially during updates, and is not supported by Arch devs.

To set up grub-bios to a partition boot sector, to a partitionless disk (also called superfloppy) or to a floppy disk, run (using for example /dev/sdaX as the /boot partition): 

# modprobe dm-mod 
# grub-install --target=i386-pc --recheck --debug --force /dev/sdaX
# chattr -i /boot/grub/i386-pc/core.img
# mkdir -p /boot/grub/locale
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
# chattr +i /boot/grub/i386-pc/core.img

You need to use the --force option to allow usage of blocklists and should not use --grub-setup=/bin/true (which is similar to simply generating core.img).

grub-install will give out warnings like which should give you the idea of what might go wrong with this approach: 

/sbin/grub-setup: warn: Attempting to install GRUB to a partitionless disk or to a partition. This is a BAD idea.
/sbin/grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. 
                        However, blocklists are UNRELIABLE and their use is discouraged.

Without --force you may get the below error and grub-setup will not setup its boot code in the partition boot sector: 

/sbin/grub-setup: error: will not proceed with blocklists

With --force you should get: 

Installation finished. No error reported.

The reason why grub-setup does not by default allow this is because in case of partition or a partitionless disk is that grub-bios relies on embedded blocklists in the partition bootsector to locate the /boot/grub/i386-pc/core.img file and the prefix dir /boot/grub. The sector locations of core.img may change whenever the filesystem in the partition is being altered (files copied, deleted etc.). For more info see https://bugzilla.redhat.com/show_bug.cgi?id=728742 and https://bugzilla.redhat.com/show_bug.cgi?id=730915.

The workaround for this is to set the immutable flag on /boot/grub/i386-pc/core.img (using chattr command as mentioned above) so that the sector locations of the core.img file in the disk is not altered. The immutable flag on /boot/grub/i386-pc/core.img needs to be set only if grub-bios is installed to a partition boot sector or a partitionless disk, not in case of installation to MBR or simple generation of core.img without embedding any bootsector (mentioned above).

Generate core.img alone

To populate the /boot/grub directory and generate a /boot/grub/i386-pc/core.img file without embedding any grub-bios bootsector code in the MBR, post-MBR region, or the partition bootsector, add --grub-setup=/bin/true to grub-install: 

# modprobe dm-mod
# grub-install --target=i386-pc --grub-setup=/bin/true --recheck --debug /dev/sda
# mkdir -p /boot/grub/locale
# cp /usr/share/locale/en@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo

You can then chainload GRUB2's core.img from GRUB Legacy or syslinux as a Linux kernel or a multiboot kernel.

Generate GRUB2 BIOS Config file

Finally, generate a configuration for GRUB2 (this is explained in greater detail in the Configuration section): 

# grub-mkconfig -o /boot/grub/grub.cfg
Note: The file path is /boot/grub/grub.cfg, NOT /boot/grub/i386-pc/grub.cfg.

If grub(2) complains about "no suitable mode found" while booting, go to #Correct GRUB2 No Suitable Mode Found Error.

If grub-mkconfig fails, convert your /boot/grub/menu.lst file to /boot/grub/grub.cfg using: 

# grub-menulst2cfg /boot/grub/menu.lst /boot/grub/grub.cfg

For example: 

/boot/grub/menu.lst
default=0
timeout=5

title  Arch Linux Stock Kernel
root   (hd0,0)
kernel /vmlinuz-linux root=/dev/sda2 ro
initrd /initramfs-linux.img

title  Arch Linux Stock Kernel Fallback
root   (hd0,0)
kernel /vmlinuz-linux root=/dev/sda2 ro
initrd /initramfs-linux-fallback.img

/boot/grub/grub.cfg
set default='0'; if [ x"$default" = xsaved ]; then load_env; set default="$saved_entry"; fi
set timeout=5

menuentry 'Arch Linux Stock Kernel' {
  set root='(hd0,1)'; set legacy_hdbias='0'
  legacy_kernel   '/vmlinuz-linux' '/vmlinuz-linux' 'root=/dev/sda2' 'ro'
  legacy_initrd '/initramfs-linux.img' '/initramfs-linux.img'
  
}

menuentry 'Arch Linux Stock Kernel Fallback' {
  set root='(hd0,1)'; set legacy_hdbias='0'
  legacy_kernel   '/vmlinuz-linux' '/vmlinuz-linux' 'root=/dev/sda2' 'ro'
  legacy_initrd '/initramfs-linux-fallback.img' '/initramfs-linux-fallback.img'
}

If you forgot to create a GRUB2 /boot/grub/grub.cfg config file and simply rebooted into GRUB2 Command Shell, type: 

sh:grub> insmod legacycfg
sh:grub> legacy_configfile ${prefix}/menu.lst

Boot into Arch and re-create the proper GRUB2 /boot/grub/grub.cfg config file.

Note: This option works only in BIOS systems, not in UEFI systems.

Multiboot in BIOS

Boot Microsoft Windows installed in BIOS-MBR mode
Note: GRUB(2) supports booting bootmgr directly and chainload of partition boot sector is no longer required to boot Windows in a BIOS-MBR setup.
Warning: Take note that it is the system partition that has bootmgr, not your "real" Windows partition (usually C:). When showing all UUIDs with blkid, the system partition is the one with LABEL="SYSTEM RESERVED" and is only about 100 MB in size (much like the boot partition for Arch). See http://en.wikipedia.org/wiki/System_partition_and_boot_partition for more info.

Find the UUID of the NTFS filesystem of the Windows's SYSTEM PARTITION where the bootmgr and its files reside. For example, if Windows bootmgr exists at /media/SYSTEM_RESERVED/bootmgr:

For Windows Vista/7/8: 

# grub-probe --target=fs_uuid /media/SYSTEM_RESERVED/bootmgr
69B235F6749E84CE

# grub-probe --target=hints_string /media/SYSTEM_RESERVED/bootmgr
--hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1
Note: grub-probe should be run as root.
Note: For Windows XP, replace bootmgr with ntldr in the above commands.

Then, add the below code to /etc/grub.d/40_custom or /boot/grub/custom.cfg and regenerate grub.cfg with grub-mkconfig as explained above to boot Windows (XP, Vista, 7 or 8) installed in BIOS-MBR mode:

For Windows Vista/7/8: 

menuentry "Microsoft Windows Vista/7/8 BIOS-MBR" {
    insmod part_msdos
    insmod ntfs
    insmod search_fs_uuid
    insmod ntldr     
    search --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 69B235F6749E84CE
    ntldr /bootmgr
}

For Windows XP: 

menuentry "Microsoft Windows XP" {
    insmod part_msdos
    insmod ntfs
    insmod search_fs_uuid
    insmod ntldr     
    search --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 69B235F6749E84CE
    ntldr /ntldr
}

/etc/grub.d/40_custom can be used as a template to create /etc/grub.d/nn_custom. Where nn defines the precendence, indicating the order the script is executed. The order scripts are executed determine the placement in the grub boot menu.

Note: nn should be greater than 06 to ensure necessary scripts are executed first.

UEFI systems

Note: It is recommended to read the UEFI, GPT and UEFI Bootloaders pages before reading this part.

Hardware-Specific UEFI Examples

It is well know that different motherboard manufactures implement UEFI differently. Users experiencing problems getting Grub/EFI to work properly are encouraged to share detailed steps for hardware-specific cases where UEFI booting does not work as described below. In an effort to keep the parent GRUB article neat and tidy, see the GRUB EFI Examples page for these special cases.

Install grub-uefi package

Note: Unless specified as EFI 1.x , EFI and UEFI terms are used interchangeably to denote UEFI 2.x firmware. Also unless stated explicitly, the instructions are general and not Mac specific. Some of them may not work or may be different in Macs. Apple's EFI implementation is neither a EFI 1.x version nor UEFI 2.x version but mixes up both. This kind of firmware does not fall under any one UEFI Specification version and is therefore not a standard UEFI firmware.

GRUB(2) UEFI bootloader is available in Arch Linux only from version 1.99~rc1. To install, first detect which UEFI firmware arch you have (either x86_64 or i386).

Depending on that, install the appropriate package

For 64-bit aka x86_64 UEFI firmware: 

# pacman -S grub-efi-x86_64

For 32-bit aka i386 UEFI firmware: 

# pacman -S grub-efi-i386
Note: Simply installing the package will not update the core.efi file and the GRUB(2) modules in the UEFI System Partition. You need to do this manually using grub-install as explained below.

Install grub-uefi boot files

Install to UEFI System Partition
Note: The below commands assume you are using grub-efi-x86_64 (for grub-efi-i386 replace x86_64 with i386 in the below commands).
Note: To do this, you need to boot using UEFI and not the BIOS. If you booted by just copying the ISO file to the USB drive, you will need to follow this guide or grub-install will show errors.

The UEFI system partition will need to be mounted at /boot/efi/ for the GRUB(2) install script to detect it: 

# mkdir -p /boot/efi
# mount -t vfat /dev/sdXY /boot/efi

Install GRUB UEFI application to /boot/efi/EFI/arch_grub and its modules to /boot/grub/x86_64-efi (recommended) using: 

# modprobe dm-mod
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --recheck --debug
# mkdir -p /boot/grub/locale
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/grub/locale/en.mo
Note: Without --target or --directory option, grub-install cannot determine for which firmware grub(2) is being installed. In such cases grub-install will show source_dir doesn't exist. Please specify --target or --directory message.

If you want to install grub(2) modules and grub.cfg at the directory /boot/efi/EFI/grub and the grubx64.efi application at /boot/efi/EFI/arch_grub (ie. all the grub(2) uefi files inside the UEFISYS partition itself) use: 

# modprobe dm-mod 
# grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=arch_grub --boot-directory=/boot/efi/EFI --recheck --debug
# mkdir -p /boot/efi/EFI/grub/locale
# cp /usr/share/locale/en\@quot/LC_MESSAGES/grub.mo /boot/efi/EFI/grub/locale/en.mo

The --efi-directory option mentions the mountpoint of UEFI SYSTEM PARTITION , --bootloader-id mentions the name of the directory used to store the grubx64.efi file and --boot-directory mentions the directory wherein the actual modules will be installed (and into which grub.cfg should be created).

The actual paths are: 

<efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi

<boot-directory>/grub/x86_64-efi/<all modules, grub.efi, core.efi, grub.cfg>
Note: the --bootloader-id option does not change <boot-directory>/grub, i.e. you cannot install the modules to <boot-directory>/<bootloader-id>, the path is hard-coded to be <boot-directory>/grub.

In --efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=grub: 

<efi-directory>/<EFI or efi>/<bootloader-id> == <boot-directory>/grub == /boot/efi/EFI/grub

In --efi-directory=/boot/efi --boot-directory=/boot/efi/EFI --bootloader-id=arch_grub: 

<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub
<boot-directory>/grub == /boot/efi/EFI/grub

In --efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=arch_grub: 

<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/arch_grub
<boot-directory>/grub == /boot/grub

In --efi-directory=/boot/efi --boot-directory=/boot --bootloader-id=grub: 

<efi-directory>/<EFI or efi>/<bootloader-id> == /boot/efi/EFI/grub
<boot-directory>/grub == /boot/grub

The <efi-directory>/<EFI or efi>/<bootloader-id>/grubx64.efi is an exact copy of <boot-directory>/grub/x86_64-efi/core.efi.

Note: In GRUB 2.00, the grub-install option --efi-directory replaces --root-directory and the latter is deprecated.
Note: The options --efi-directory and --bootloader-id are specific to GRUB(2) UEFI.

In all the cases the UEFI SYSTEM PARTITION should be mounted for grub-install to install grubx64.efi in it, which will be launched by the firmware (using the efibootmgr created boot entry in non-Mac systems).

If you notice carefully, there is no <device_path> option (Eg: /dev/sda) at the end of the grub-install command unlike the case of setting up GRUB(2) for BIOS systems. Any <device_path> provided will be ignored by the install script as UEFI bootloaders do not use MBR or Partition boot sectors at all.

You may now be able to UEFI boot your system by creating a grub.cfg file by following #Generate GRUB2 UEFI Config file and #Create GRUB2 entry in the Firmware Boot Manager.

Generate GRUB2 UEFI Config file

Finally, generate a configuration for GRUB(2) (this is explained in greater detail in the Configuration section): 

# grub-mkconfig -o <boot-directory>/grub/grub.cfg
Note: The file path is <boot-directory>/grub/grub.cfg, NOT <boot-directory>/grub/x86_64-efi/grub.cfg.

If you used --boot-directory=/boot: 

# grub-mkconfig -o /boot/grub/grub.cfg

If you used --boot-directory=/boot/efi/EFI: 

# grub-mkconfig -o /boot/efi/EFI/grub/grub.cfg

This is independent of the value of --bootloader-id option.

If GRUB2 complains about "no suitable mode found" while booting, try #Correct GRUB2 No Suitable Mode Found Error.

Create GRUB2 entry in the Firmware Boot Manager

As of grub-efi-x86_64 version 2.00, grub-install automatically tries to create a menu entry in the boot manager. If it doesn't, then see Beginners' Guide#GRUB for instructions to use efibootmgr to create a menu entry. However, the problem is likely to be that you haven't booted your CD/USB in UEFI mode, as in Unified Extensible Firmware Interface#Create UEFI bootable USB from ISO.

Create GRUB2 Standalone UEFI Application

It is possible to create a grubx64_standalone.efi application which has all the modules embeddded in a memdisk within the uefi application, thus removing the need for having a separate directory populated with all the GRUB2 uefi modules and other related files. This is done using the grub-mkstandalone command which is included in grub-common >= 1:1.99-6 package.

The easiest way to do this would be with the install command already mentioned before, but specifying the modules to include. For example: 

# grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \
--output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" <any extra files you want to include>

The grubx64_standalone.efi file expects grub.cfg to be within its $prefix which is (memdisk)/boot/grub. The memdisk is embedded within the efi app. The grub-mkstandlone script allow passing files to be included in the memdisk image to be as the arguments to the script (in <any extra files you want to include>).

If you have the grub.cfg at /home/user/Desktop/grub.cfg, then create a temporary /home/user/Desktop/boot/grub/ directory, copy the /home/user/Desktop/grub.cfg to /home/user/Desktop/boot/grub/grub.cfg, cd into /home/user/Desktop/boot/grub/ and run: 

# grub-mkstandalone --directory="/usr/lib/grub/x86_64-efi/" --format="x86_64-efi" --compression="xz" \
--output="/boot/efi/EFI/arch_grub/grubx64_standalone.efi" "boot/grub/grub.cfg"

The reason to cd into /home/user/Desktop/boot/grub/ and to pass the file path as boot/grub/grub.cfg (notice the lack of a leading slash - boot/ vs /boot/ ) is because dir1/dir2/file is included as (memdisk)/dir1/dir2/file by the grub-mkstandalone script.

If you pass /home/user/Desktop/grub.cfg the file will be included as (memdisk)/home/user/Desktop/grub.cfg. If you pass /home/user/Desktop/boot/grub/grub.cfg the file will be included as (memdisk)/home/user/Desktop/boot/grub/grub.cfg. That is the reason for cd'ing into /home/user/Desktop/boot/grub/ and passing boot/grub/grub.cfg, to include the file as (memdisk)/boot/grub/grub.cfg, which is what grub.efi expects the file to be.

You need to create an UEFI Boot Manager entry for /boot/efi/EFI/arch_grub/grubx64_standalone.efi using efibootmgr. Follow #Create GRUB2 entry in the Firmware Boot Manager.

Multiboot in UEFI

Chainload Microsoft Windows x86_64 UEFI-GPT

Find the UUID of the FAT32 filesystem in the UEFI SYSTEM PARTITION where the Windows UEFI Bootloader files reside. For example, if Windows bootmgfw.efi exists at /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi (ignore the upper-lower case differences since that is immaterial in FAT filesystem): 

# grub-probe --target=fs_uuid /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi
1ce5-7f28

# grub-probe --target=hints_string /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi
--hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1
Note: grub-probe should be run as root.

Then, add this code to /etc/grub.d/40_custom to chainload Windows x86_64 (Vista SP1+, 7 or 8) installed in UEFI-GPT mode: 

menuentry "Microsoft Windows Vista/7/8 x86_64 UEFI-GPT" {
    insmod part_gpt
    insmod fat
    insmod search_fs_uuid
    insmod chain
    search --fs-uuid --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1 1ce5-7f28
    chainloader /efi/Microsoft/Boot/bootmgfw.efi
}

Afterwards remake /boot/grub/grub.cfg 

# grub-mkconfig -o /boot/grub/grub.cfg

Configuration

You can also choose to automatically generate or manually edit grub.cfg.

Note: For EFI systems, if GRUB2 was installed with the --boot-directory option set, the grub.cfg file must be placed in the same directory as grubx64.efi. Otherwise, the grub.cfg file goes in /boot/grub/, just like in the BIOS version of GRUB2.
Note: Here is a quite complete description of how to configure GRUB2: http://members.iinet.net/~herman546/p20/GRUB2%20Configuration%20File%20Commands.html

Automatically generating using grub-mkconfig (Recommended)

The GRUB2 menu.lst equivalent configuration files are /etc/default/grub and /etc/grub.d/*. grub-mkconfig uses these files to generate grub.cfg. By default the script outputs to stdout. To generate a grub.cfg file run the command: 

# grub-mkconfig -o /boot/grub/grub.cfg

/etc/grub.d/10_linux is set to automatically add menu items for Arch linux that work out of the box, to any generated configuration. Other operating systems may need to be added manually to /etc/grub.d/40_custom or /boot/grub/custom.cfg

Additional arguments

To pass custom additional arguments to the Linux image, you can set the GRUB_CMDLINE_LINUX variable in /etc/default/grub.

For example, use GRUB_CMDLINE_LINUX="resume=/dev/sdaX" where sdaX is your swap partition to enable resume after hibernation.

You can also use GRUB_CMDLINE_LINUX="resume=/dev/disk/by-uuid/${swap_uuid}", where ${swap_uuid} is the UUID of your swap partition.

Multiple entries are separated by spaces within the double quotes. So, for users who want both resume and systemd it would look like this: GRUB_CMDLINE_LINUX="resume=/dev/sdaX init=/usr/lib/systemd/systemd"

See Kernel parameters for more info.

Manually creating grub.cfg

Warning: Editing this file is strongly not recommended. The file is generated by the grub-mkconfig command, and it is best to edit your /etc/default/grub or one of the scripts in the /etc/grub.d folder.

A basic GRUB config file uses the following options

  • (hdX,Y) is the partition Y on disk X, partition numbers starting at 1, disk numbers starting at 0
  • set default=N is the default boot entry that is chosen after timeout for user action
  • set timeout=M is the time M to wait in seconds for a user selection before default is booted
  • menuentry "title" {entry options} is a boot entry titled title
  • set root=(hdX,Y) sets the boot partition, where the kernel and GRUB modules are stored (boot need not be a separate partition, and may simply be a directory under the "root" partition (/)

An example configuration: 

/boot/grub/grub.cfg

# Config file for GRUB2 - The GNU GRand Unified Bootloader
# /boot/grub/grub.cfg

# DEVICE NAME CONVERSIONS
#
#  Linux           Grub
# -------------------------
#  /dev/fd0        (fd0)
#  /dev/sda        (hd0)
#  /dev/sdb2       (hd1,2)
#  /dev/sda3       (hd0,3)
#

# Timeout for menu
set timeout=5

# Set default boot entry as Entry 0
set default=0

# (0) Arch Linux
menuentry "Arch Linux" {
    set root=(hd0,1)
    linux /vmlinuz-linux root=/dev/sda3 ro
    initrd /initramfs-linux.img
}

## (1) Windows
#menuentry "Windows" {
#set root=(hd0,3)
#chainloader +1
#}

Dual-booting

Note: If you want GRUB2 to automatically search for other systems, you may wish to install os-prober.

Using grub-mkconfig

The best way to add other entries is editing the /etc/grub.d/40_custom or /boot/grub/custom.cfg . The entries in this file will be automatically added when running grub-mkconfig. After adding the new lines, run: 

# grub-mkconfig -o /boot/grub/grub.cfg

to generate an updated grub.cfg.

With GNU/Linux

Assuming that the other distro is on partition sda2: 

menuentry "Other Linux" {
set root=(hd0,2)
linux /boot/vmlinuz (add other options here as required)
initrd /boot/initrd.img (if the other kernel uses/needs one)
}
With FreeBSD

Requires that FreeBSD is installed on a single partition with UFS. Assuming it is installed on sda4: 

menuentry "FreeBSD" {
set root=(hd0,4)
chainloader +1
}
With Windows

This assumes that your Windows partition is sda3. Remember you need to point set root and chainloader to the system reserve partition that windows made when it installed, not the actual partition windows is on. This example works if your system reserve partition is sda3. 

# (2) Windows XP
menuentry "Windows XP" {
    set root=(hd0,3)
    chainloader (hd0,3)+1
}

If the Windows bootloader is on an entirely different hard drive than GRUB, it may be necessary to trick Windows into believing that it is the first hard drive. This was possible with drivemap. Assuming GRUB is on hd0 and Windows is on hd2, you need to add the following after set root: 

drivemap -s hd0 hd2

With Windows via EasyBCD and NeoGRUB

Since EasyBCD's NeoGRUB currently does not understand the GRUB2 menu format, chainload to it by replacing the contents of your C:\NST\menu.lst file with lines similar to the following: 

default 0
timeout 1

title       Chainload into GRUB v2
root        (hd0,7)
kernel      /boot/grub/i386-pc/core.img

Visual Configuration

In GRUB2 it is possible, by default, to change the look of the menu. Make sure to initialize, if not done already, GRUB2 graphical terminal, gfxterm, with proper video mode, gfxmode, in GRUB2. This can be seen in the section #Correct_GRUB2_No_Suitable_Mode_Found_Error. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload' so any visual configurations need this mode in order to be in effect.

Setting the framebuffer resolution

GRUB2 can set the framebuffer for both GRUB2 itself and the kernel. The old vga= way is deprecated. The preferred method is editing /etc/default/grub as the following sample: 

GRUB_GFXMODE=1024x768x32
GRUB_GFXPAYLOAD_LINUX=keep

To generate the changes, run: 

# grub-mkconfig -o /boot/grub/grub.cfg

The gfxpayload property will make sure the kernel keeps the resolution.

Note: If this example does not work for you try to replace gfxmode="1024x768x32" by vbemode="0x105". Remember to replace the specified resolution with one suitable for your screen.
Note: To show all the modes you can use # hwinfo --framebuffer (hwinfo is available in [community]), while at GRUB2 prompt you can use the vbeinfo command.

If this method does not work for you, the deprecated vga= method will still work. Just add it next to the "GRUB_CMDLINE_LINUX_DEFAULT=" line in /etc/default/grub for eg: "GRUB_CMDLINE_LINUX_DEFAULT="quiet splash vga=792" will give you a 1024x768 resolution.

You can choose one of these resolutions: 640×480, 800×600, 1024×768, 1280×1024, 1600×1200, 1920×1200

915resolution hack

Some times for Intel graphic adapters neither # hwinfo --framebuffer nor vbeinfo will show you the desired resolution. In this case you can use 915resolution hack. This hack will temporarily modify video BIOS and add needed resolution. See 915resolution's home page

In the following I will proceed with the example for my system. Please adjust the recipe for your needs. First you need to find a video mode which will be modified later. For that, run 915resolution in GRUB2 command shell: 

915resolution -l

The output will be something like: 

Intel 800/900 Series VBIOS Hack : version 0.5.3
...
Mode 30 : 640x480, 8 bits/pixel
...

Next, our purpose is to overwrite mode 30. (You can choose what ever mode you want.) In the file /etc/grub.d/00_header just before the set gfxmode=${GRUB_GFXMODE} line insert: 

915resolution 30 1440 900

Here we are overwriting the mode 30 with 1440x900 resolution. Lastly we need to set GRUB_GFXMODE as described earlier, regenerate GRUB2 configuration file and reboot to test changes: 

# grub-mkconfig -o /boot/grub/grub.cfg
# reboot

Background image and bitmap fonts

GRUB2 comes with support for background images and bitmap fonts in pf2 format. The unifont font is included in the grub-common package under the filename unicode.pf2, or, as only ASCII characters under the name ascii.pf2.

Image formats supported include tga, png and jpeg, providing the correct modules are loaded. The maximum supported resolution depends on your hardware.

Make sure you have set up the proper framebuffer resolution.

Edit /etc/default/grub like this: 

GRUB_BACKGROUND="/boot/grub/myimage"
#GRUB_THEME="/path/to/gfxtheme"
GRUB_FONT="/path/to/font.pf2"
Note: If you have installed GRUB on a separate partition, /boot/grub/myimage becomes /grub/myimage.

To generate the changes and add the information into grub.cfg, run: 

grub-mkconfig -o /boot/grub/grub.cfg

If adding the splash image was successful, the user will see "Found background image..." in the terminal as the command is executed. If this phrase is not seen, the image information was probably not incorporated into the grub.cfg file.

If the image is not displayed, check:

  • The path and the filename in /etc/default/grub are correct.
  • The image is of the proper size and format (tga, png, 8-bit jpg).
  • The image was saved in the RGB mode, and is not indexed.
  • The console mode is not enabled in /etc/default/grub.
  • The command grub-mkconfig must be executed to place the background image information into the /boot/grub/grub.cfg file.

Theme

Here is an example for configuring Starfield theme which was included in GRUB2 package.

Edit /etc/default/grub 

GRUB_THEME="/usr/share/grub/themes/starfield/theme.txt"

Generate the changes: 

grub-mkconfig -o /boot/grub/grub.cfg

If configuring the theme was successful, you'll see Found theme: /usr/share/grub/themes/starfield/theme.txt in the terminal. Your splash image will usually not be displayed when using a theme.

Menu colors

You can set the menu colors in GRUB2. The available colors for GRUB2 can be found in the GRUB Manual. Here is an example:

Edit /etc/default/grub: 

GRUB_COLOR_NORMAL="light-blue/black"
GRUB_COLOR_HIGHLIGHT="light-cyan/blue"

Generate the changes: 

grub-mkconfig -o /boot/grub/grub.cfg

Hidden menu

One of the unique features of GRUB2 is hiding/skipping the menu and showing it by holding Template:Keypress when needed. You can also adjust whether you want to see the timeout counter.

Edit /etc/default/grub as you wish. Here is an example where the comments from the beginning of the two lines have been removed to enable the feature, the timeout has been set to five seconds and to be shown to the user: 

GRUB_HIDDEN_TIMEOUT=5
GRUB_HIDDEN_TIMEOUT_QUIET=false

and run: 

# grub-mkconfig -o /boot/grub/grub.cfg

Disable framebuffer

Users who use NVIDIA proprietary driver might wish to disable GRUB2's framebuffer as it can cause problems with the binary driver.

To disable framebuffer, edit /etc/default/grub and uncomment the following line: 

GRUB_TERMINAL_OUTPUT=console

and run: 

grub-mkconfig -o /boot/grub/grub.cfg

Other Options

LVM

If you use LVM for your /boot, add the following before menuentry lines: 

insmod lvm

and specify your root in the menuentry as: 

set root=lvm/lvm_group_name-lvm_logical_boot_partition_name

Example: 

# (0) Arch Linux
menuentry "Arch Linux" {
insmod lvm
set root=lvm/VolumeGroup-lv_boot
# you can only set following two lines
linux /vmlinuz-linux root=/dev/mapper/VolumeGroup-root ro
initrd /initramfs-linux.img
}

RAID

GRUB2 provides convenient handling of RAID volumes. You need to add insmod mdraid which allows you to address the volume natively. For example, /dev/md0 becomes: 

set root=(md0)

whereas a partitioned RAID volume (e.g. /dev/md0p1) becomes: 

set root=(md0,1)

Persistent block device naming

One naming scheme for Persistent block device naming is the use of globally unique UUIDs to detect partitions instead of the "old" /dev/sd*. Advantages are covered up in the above linked article.

Persistent naming via filesystem UUIDs are used by default in GRUB2.

Note: The /boot/grub.cfg file needs regeneration with the new UUID in /etc/default/grub every time a relevant filesystem is resized or recreated. Remember this when modifying partitions & filesystems with a Live-CD.

Whether to use UUIDs is controlled by an option in /etc/default/grub: 

# GRUB_DISABLE_LINUX_UUID=true

Either way, do not forget to generate the changes: 

# grub-mkconfig -o /boot/grub/grub.cfg

Using Labels

It is possible to use labels, human-readable strings attached to filesystems, by using the --label option to search. First of all, label your existing partition: 

# tune2fs -L <LABEL> <PARTITION>

Then, add an entry using labels. An example of this: 

menuentry "Arch Linux, session texte" {
    search --label --set=root archroot
    linux /boot/vmlinuz-linux root=/dev/disk/by-label/archroot ro
    initrd /boot/initramfs-linux.img
}

Recall previous entry

GRUB2 can remember the last entry you booted from and use this as the default entry to boot from next time. This is useful if you have multiple kernels (i.e., the current Arch one and the LTS kernel as a fallback option) or operating systems. To do this, edit /etc/default/grub and change the setting of GRUB_DEFAULT: 

GRUB_DEFAULT=saved

This ensures that GRUB will default to the saved entry. To enable saving the selected entry, add the following line to /etc/default/grub: 

GRUB_SAVEDEFAULT=true
Note: Manually added menu items, eg Windows in /etc/grub.d/40_custom or /boot/grub/custom.cfg , will need savedefault added. Remember to regenerate your configuration file.

Security

If you want to secure GRUB2 so it is not possible for anyone to change boot parameters or use the command line, you can add a user/password combination to GRUB2's configuration files. To do this, run the command grub-mkpasswd-pbkdf2. Enter a password and confirm it. The output will look like this: 

Your PBKDF2 is grub.pbkdf2.sha512.10000.C8ABD3E93C4DFC83138B0C7A3D719BC650E6234310DA069E6FDB0DD4156313DA3D0D9BFFC2846C21D5A2DDA515114CF6378F8A064C94198D0618E70D23717E82.509BFA8A4217EAD0B33C87432524C0B6B64B34FBAD22D3E6E6874D9B101996C5F98AB1746FE7C7199147ECF4ABD8661C222EEEDB7D14A843261FFF2C07B1269A
Then, add the following to /etc/grub.d/00_header: 
cat << EOF

set superusers="username"
password_pbkdf2 username <password>

EOF

where <password> is the string generated by grub-mkpasswd_pbkdf2.

Regenerate your configuration file. Your GRUB2 command line, boot parameters and all boot entries are now protected.

This can be relaxed and further customized with more users as described in the "Security" part of the GRUB manual.

Root Encryption

To let GRUB2 automatically add the kernel parameters for root encryption, add cryptdevice=/dev/yourdevice:label to GRUB_CMDLINE_LINUX in /etc/default/grub.

Example with root mapped to /dev/mapper/root: 

GRUB_CMDLINE_LINUX="cryptdevice=/dev/sda2:root"

Also, disable the usage of UUIDs for the rootfs: 

GRUB_DISABLE_LINUX_UUID=true

Regenerate the configuration.

Boot non-default entry only once

The command grub-reboot is very helpful to boot another entry than the default only once. GRUB2 loads the entry passed in the first command line argument, when the system is rebooted the next time. Most importantly GRUB2 returns to loading the default entry for all future booting. Changing the configuration file or selecting an entry in the GRUB2 menu is not necessary.

Booting an ISO Directly From GRUB2

Edit /etc/grub.d/40_custom or /boot/grub/custom.cfg to add an entry for the target ISO. When finished, update the GRUB menu as with the usual grub-mkconfig -o /boot/grub/grub.cfg (as root).

Arch ISO

Note: The example assumes that the iso is in /archives on hd0,6. Users must adjust the location and hdd/partition in ALL of the lines below to match their systems. However, if booting the ISO from USB on a computer which also has one internal HDD, then it needs to be hd0,Y with sdbY, instead of sdaY.

Example using x86_64 

menuentry "Archlinux-2013.01.04-dual.iso" --class iso {
  set isofile="/archives/archlinux-2013.01.04-dual.iso"
  loopback loop (hd0,6)$isofile
  linux (loop)/arch/boot/x86_64/vmlinuz archisolabel=ARCH_201301 img_dev=/dev/sda6 img_loop=$isofile earlymodules=loop
  initrd (loop)/arch/boot/x86_64/archiso.img
}

Example using i686 

menuentry "Archlinux-2013.01.04-dual.iso" --class iso {
  set isofile="/archives/archlinux-2013.01.04-dual.iso"
  loopback loop (hd0,6)$isofile
  linux (loop)/arch/boot/i686/vmlinuz archisolabel=ARCH_201301 img_dev=/dev/sda6 img_loop=$isofile earlymodules=loop
  initrd (loop)/arch/boot/i686/archiso.img
}
Tip: For thumbdrives, use Persistent block device names for the "img_dev" kernel parameter. Ex: img_dev=/dev/disk/by-label/CORSAIR

Ubuntu ISO

Note: The example assumes that the iso is in /archives on hd0,6. Users must adjust the location and hdd/partition in the lines below to match their systems.
menuentry "ubuntu-12.04-desktop-amd64.iso" {
    set isofile="/archives/ubuntu-12.04-desktop-amd64.iso"
    loopback loop (hd0,6)$isofile
    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile quiet noeject noprompt splash --
    initrd (loop)/casper/initrd.lz
}

Other ISOs

Other working configurations from link Source.

Using the command shell

Since the MBR is too small to store all GRUB2 modules, only the menu and a few basic commands reside there. The majority of GRUB2 functionality remains in modules in /boot/grub, which are inserted as needed. In error conditions (e.g. if the partition layout changes) GRUB2 may fail to boot. When this happens, a command shell may appear.

GRUB2 offers multiple shells/prompts. If there is a problem reading the menu but the bootloader is able to find the disk, you will likely be dropped to the "normal" shell: 

sh:grub>

If there is a more serious problem (e.g. GRUB cannot find required files), you may instead be dropped to the "rescue" shell: 

grub rescue>

The rescue shell is a restricted subset of the normal shell, offering much less functionality. If dumped to the rescue shell, first try inserting the "normal" module, then starting the "normal" shell: 

grub rescue> set prefix=(hdX,Y)/boot/grub
grub rescue> insmod (hdX,Y)/boot/grub/i386-pc/normal.mod
rescue:grub> normal

Pager support

GRUB2 supports pager for reading commands that provide long output (like the help command). This works only in normal shell mode and not in rescue mode. To enable pager, in GRUB2 command shell type: 

sh:grub> set pager=1

GUI configuration tools

Following package may be installed from AUR

  • grub-customizerAUR (requires gettext gksu gtkmm hicolor-icon-theme openssl)
    Customize the bootloader (GRUB2 or BURG)
  • grub2-editorAUR (requires kdelibs)
    A KDE4 control module for configuring the GRUB2 bootloader
  • kcm-grub2AUR (requires kdelibs python2-qt kdebindings-python)
    This Kcm module manages the most common settings of Grub2.
  • startupmanagerAUR (requires gnome-python imagemagick yelp python2 xorg-xrandr)
    GUI app for changing the settings of GRUB, GRUB2, Usplash and Splashy

parttool for hide/unhide

If you have a Windows 9x paradigm with hidden C:\ disks GRUB can hide/unhide it using parttool. For example, to boot the third C:\ disk of three Windows 9x installations on the CLI enter the CLI and: 

parttool hd0,1 hidden+ boot-
parttool hd0,2 hidden+ boot-
parttool hd0,3 hidden- boot+
set root=hd0,3
chainloader +1
boot

Using the rescue console

See #Using the command shell first. If unable to activate the standard shell, one possible solution is to boot using a live CD or some other rescue disk to correct configuration errors and reinstall GRUB. However, such a boot disk is not always available (nor necessary); the rescue console is surprisingly robust.

The available commands in GRUB rescue include insmod, ls, set, and unset. This example uses set and insmod. set modifies variables and insmod inserts new modules to add functionality.

Before starting, the user must know the location of their /boot partition (be it a separate partition, or a subdirectory under their root): 

grub rescue> set prefix=(hdX,Y)/boot/grub

where X is the physical drive number and Y is the partition number.

To expand console capabilities, insert the linux module: 

grub rescue> insmod (hdX,Y)/boot/grub/linux.mod
Note: With a separate boot partition, omit /boot from the path, (i.e. type set prefix=(hdX,Y)/grub and insmod (hdX,Y)/grub/linux.mod).

This introduces the linux and initrd commands, which should be familiar (see #Configuration).

An example, booting Arch Linux: 

set root=(hd0,5)
linux /boot/vmlinuz-linux root=/dev/sda5
initrd /boot/initramfs-linux.img
boot

With a separate boot partition, again change the lines accordingly: 

set root=(hd0,5)
linux /vmlinuz-linux root=/dev/sda6
initrd /initramfs-linux.img
boot

After successfully booting the Arch Linux installation, users can correct grub.cfg as needed and then reinstall GRUB2.

to reinstall GRUB2 and fix the problem completely, changing /dev/sda if needed. See #Bootloader installation for details.

Combining the use of UUIDs and basic scripting

If you like the idea of using UUIDs to avoid unreliable BIOS mappings or are struggling with GRUB's syntax, here is an example boot menu item that uses UUIDs and a small script to direct GRUB to the proper disk partitions for your system. All you need to do is replace the UUIDs in the sample with the correct UUIDs for your system. The example applies to a system with a boot and root partition. You will obviously need to modify the GRUB configuration if you have additional partitions: 

 menuentry "Arch Linux 64" {
     # Set the UUIDs for your boot and root partition respectively
     set the_boot_uuid=ece0448f-bb08-486d-9864-ac3271bd8d07
     set the_root_uuid=c55da16f-e2af-4603-9e0b-03f5f565ec4a
   
     # (Note: This may be the same as your boot partition)
   
     # Get the boot/root devices and set them in the root and grub_boot variables
     search --fs-uuid --set=root $the_root_uuid
     search --fs-uuid --set=grub_boot $the_boot_uuid
   
     # Check to see if boot and root are equal.
     # If they are, then append /boot to $grub_boot (Since $grub_boot is actually the root partition)
     if [ $the_boot_uuid == $the_root_uuid] ; then
         set grub_boot=$grub_boot/boot
     fi
   
     # $grub_boot now points to the correct location, so the following will properly find the kernel and initrd
     linux ($grub_boot)/vmlinuz-linux root=/dev/disk/by-uuid/$uuid_os_root ro
     initrd ($grub_boot)/initramfs-linux.img
 }

Troubleshooting

Any troubleshooting should be added here.

Enable GRUB2 debug messages

Add: 

set pager=1
set debug=all

to grub.cfg.

Correct GRUB2 No Suitable Mode Found Error

If you get this error when booting any menuentry: 

error: no suitable mode found
Booting however

Then you need to initialize GRUB2 graphical terminal (gfxterm) with proper video mode (gfxmode) in GRUB2. This video mode is passed by GRUB2 to the linux kernel via 'gfxpayload'. In case of UEFI systems, if the GRUB2 video mode is not initialized, no kernel boot messages will be shown in the terminal (atleast until KMS kicks in).

Copy /usr/share/grub/unicode.pf2 to ${GRUB2_PREFIX_DIR} (/boot/grub/ in case of BIOS and UEFI systems). If GRUB2 UEFI was installed with --boot-directory=/boot/efi/EFI set, then the directory is /boot/efi/EFI/grub/: 

# cp /usr/share/grub/unicode.pf2 ${GRUB2_PREFIX_DIR}

If /usr/share/grub/unicode.pf2 does not exist, install bdf-unifont, create the unifont.pf2 file and then copy it to ${GRUB2_PREFIX_DIR}: 

# grub-mkfont -o unicode.pf2 /usr/share/fonts/misc/unifont.bdf

Then, in the grub.cfg file, add the following lines to enable GRUB2 to pass the video mode correctly to the kernel, without of which you will only get a black screen (no output) but booting (actually) proceeds successfully without any system hang.

BIOS systems: 

insmod vbe

UEFI systems: 

insmod efi_gop
insmod efi_uga

After that add the following code (common to both BIOS and UEFI): 

insmod font

if loadfont ${prefix}/fonts/unicode.pf2
then
    insmod gfxterm
    set gfxmode=auto
    set gfxpayload=keep
    terminal_output gfxterm
fi

As you can see for gfxterm (graphical terminal) to function properly, unicode.pf2 font file should exist in ${GRUB2_PREFIX_DIR}.

msdos-style error message

grub-setup: warn: This msdos-style partition label has no post-MBR gap; embedding won't be possible!
grub-setup: warn: Embedding is not possible. GRUB can only be installed in this setup by using blocklists.
            However, blocklists are UNRELIABLE and its use is discouraged.
grub-setup: error: If you really want blocklists, use --force.

This error may occur when you try installing GRUB2 in a VMware container. Read more about it here. It happens when the first partition starts just after the MBR (block 63), without the usual space of 1 MiB (2048 blocks) before the first partition. Read #Master Boot Record (MBR) specific instructions

UEFI GRUB2 drops to shell

If GRUB loads but drops you into the rescue shell with no errors, it may be because of a missing or misplaced grub.cfg. This will happen if GRUB2 UEFI was installed with --boot-directory and grub.cfg is missing OR if the partition number of the boot partition changed (which is hard-coded into the grubx64.efi file).

UEFI GRUB2 not loaded

In some cases the EFI may fail to load GRUB correctly. Provided everything is set up correctly, the output of: 

efibootmgr -v

might look something like this: 

BootCurrent: 0000
Timeout: 3 seconds
BootOrder: 0000,0001,0002
Boot0000* Grub	HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\efi\grub\grub.efi)
Boot0001* Shell	HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\EfiShell.efi)
Boot0002* Festplatte	BIOS(2,0,00)P0: SAMSUNG HD204UI

If everything works correctly, the EFI would now automatically load GRUB.

If the screen only goes black for a second and the next boot option is tried afterwards, according to this post, moving GRUB to the partition root can help. The boot option has to be deleted and recreated afterwards. The entry for GRUB should look like this then: 

Boot0000* Grub	HD(1,800,32000,23532fbb-1bfa-4e46-851a-b494bfe9478c)File(\grub.efi)

Invalid signature

If trying to boot Windows results in an "invalid signature" error, e.g. after reconfiguring partitions or adding additional hard drives, (re)move GRUB's device configuration and let it reconfigure: 

# mv /boot/grub/device.map /boot/grub/device.map-old
# grub-mkconfig -o /boot/grub/grub.cfg

grub-mkconfig should now mention all found boot options, including Windows. If it works, remove /boot/grub/device.map-old.

Boot freezes

If booting gets stuck without any error message after grub2 loading the kernel and the initial ramdisk, try removing the add_efi_memmap kernel parameter.

Restore GRUB Legacy

  • Move GRUB2 files out of the way:
# mv /boot/grub /boot/grub.nonfunctional
  • Copy GRUB Legacy back to /boot:
# cp -af /boot/grub-legacy /boot/grub
  • Replace MBR and next 62 sectors of sda with backed up copy
Warning: This command also restores the partition table, so be careful of overwriting a modified partition table with the old one. It will mess up your system.
# dd if=/path/to/backup/first-sectors of=/dev/sdX bs=512 count=1

A safer way is to restore only the MBR boot code use: 

# dd if=/path/to/backup/mbr-boot-code of=/dev/sdX bs=446 count=1

References

  1. Official GRUB2 Manual - https://www.gnu.org/software/grub/manual/grub.html
  2. Ubuntu wiki page for GRUB2 - https://help.ubuntu.com/community/Grub2
  3. GRUB2 wiki page describing steps to compile for UEFI systems - https://help.ubuntu.com/community/UEFIBooting
  4. Wikipedia's page on BIOS Boot partition

External Links

  1. A Linux Bash Shell script to compile and install GRUB(2) for BIOS from BZR Source
  2. A Linux Bash Shell script to compile and install GRUB(2) for UEFI from BZR Source
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