Difference between revisions of "UEFI Bootloaders"

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[[Category:Boot loaders]]
[[zh-CN:UEFI Bootloaders]]
This page contains info about various [[UEFI]] Bootloaders capable of booting Linux kernel. It is recommended to read the [[UEFI]] and [[GPT]] pages before reading this page. The following [[Boot Loader|bootloaders]] (listed in decreasing order of stability) are explained here:
# Linux Kernel EFISTUB
#redirect [[ArchWiki:Archive]]
# GRUB 2.x
# Gummiboot
# SYSLINUX (GIT Alpha Version)
== Linux Kernel EFISTUB ==
Linux Kernel >= 3.3 contains a stub which is capable of acting as the kernel's UEFI bootloader (which in a way means the kernel is its own bootloader), thus removing the need for a separate bootloader to launch the kernel (a boot manager might be required though, explained in detail later). This support is called {{ic|EFI BOOT STUB}} by upstream or {{ic|EFISTUB}} in short. EFISTUB should enabled by setting {{ic|1=CONFIG_EFI_STUB=y}} in Kernel config. The upstream documentation about EFISTUB booting is at https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob_plain;f=Documentation/x86/efi-stub.txt;hb=HEAD . More (unofficial) info is at http://www.rodsbooks.com/efi-bootloaders/efistub.html .
Since the kernel is responsible for booting only itself, a single EFISTUB enabled kernel is not capable of launching other kernels. And each EFISTUB Kernel+Initramfs pair requires a separate boot menu entry. Thus when multiple kernels and/or initramfs files are involved, a UEFI Boot Manager is recommended to manage them.
=== Setting up EFISTUB ===
# Create an FAT32 UEFI System Partition - [[Unified_Extensible_Firmware_Interface#Create_an_UEFI_System_Partition_in_Linux]]
# Mount the UEFI System Partition at {{ic|/boot/efi}}.
# Create {{ic|/boot/efi/EFI/arch/}} directory.
# Copy {{ic|/boot/vmlinuz-linux}} to {{ic|/boot/efi/EFI/arch/vmlinuz-arch.efi}} . The {{ic|.efi}} file extension is very important as some UEFI firmwares refuse to launch a file without the {{ic|.efi}} file extension. '''Important:''' Remember that the file is called vmlinu'''z''', but not vmlinu'''x'''.
# Copy {{ic|/boot/initramfs-linux.img}} to {{ic|/boot/efi/EFI/arch/initramfs-arch.img}}.
# Copy {{ic|/boot/initramfs-linux-fallback.img}} to {{ic|/boot/efi/EFI/arch/initramfs-arch-fallback.img}}.
{{Note|There exists a [http://article.gmane.org/gmane.linux.kernel/1269122/ patch] for the kernel that allows passing kernel parameters via a file named {{ic|linux.conf}} placed in the same directory as the kernel when booting via EFISTUB; example
root=UUID=xxxx ro rootfstype=ext4 add_efi_memmap initrd=\EFI\arch\initramfs-arch.img</nowiki>}}
As of at least commit [https://github.com/torvalds/linux/commit/29594404d7fe73cd80eaa4ee8c43dcc53970c60e 29594404d7fe73cd80eaa4ee8c43dcc53970c60e], the {{ic|linux.conf}} patch has not been merged; you will need to apply it yourself if you wish to use this feature.}}
Finally, jump to [[#Booting_EFISTUB]] choose a way to get your machine to make use of the new EFISTUB you've just created.
{{Note|The kernel and initramfs files at {{ic|/boot/efi/EFI/arch/}} should be updated everytime those files in {{ic|/boot}} are updated.}}
{{Warning|In Linux Kernel EFISTUB booting, {{ic|1=initrd=}} path should use UEFI-style backslashes (\) and should be relative to the UEFI System Partition's root, not relative to the current directory in the UEFI Shell. An improper {{ic|1=initrd=}} option leads to a system hang without any error message from the firmware or the kernel.}}
==== Sync EFISTUB Kernel in UEFISYS partition using Systemd ====
[[Systemd]] init system supports defining tasks that should be performed when certain files/paths are changed. This feature of systemd is used to copy updated EFISTUB kernel and initramfs files when they are updated in {{ic|/boot}}, like during package updates or during manual run of mkinitcpio etc.
For this create the files as defined below:
Description=Copy EFISTUB Kernel to UEFISYS Partition
Description=Copy EFISTUB Kernel to UEFISYS Partition
ExecStart=/bin/cp -f /boot/vmlinuz-linux /boot/efi/EFI/arch/vmlinuz-arch.efi
ExecStart=/bin/cp -f /boot/initramfs-linux.img /boot/efi/EFI/arch/initramfs-arch.img
ExecStart=/bin/cp -f /boot/initramfs-linux-fallback.img /boot/efi/EFI/arch/initramfs-arch-fallback.img
After creating the files run:
# systemctl enable efistub-update.path
# systemctl start efistub-update.path
==== Sync EFISTUB Kernel in UEFISYS partition using Incron ====
Incron can also be used to automatically sync the EFISTUB kernel after updates.
First, [[pacman|install]] the {{Pkg|incron}} package from the [[Official Repositories]].
Next you will need to set up a script to do the actual copying.  You can call this script whatever you want, but make sure you use absolute paths in the commands.
{{hc|File: /usr/local/bin/efistub-update.sh|<nowiki>
/bin/cp -f /boot/vmlinuz-linux /boot/efi/EFI/arch/vmlinuz-arch.efi
/bin/cp -f /boot/initramfs-linux.img /boot/efi/EFI/arch/initramfs-arch.img
/bin/cp -f /boot/initramfs-linux-fallback.img /boot/efi/EFI/arch/initramfs-arch-fallback.img
Specify which file to watch for changes in {{ic|/etc/incron.d/efistub-update.conf}}.  The first parameter is the file to watch: {{ic|/boot/initramfs-linux-fallback.img}}.  The second parameter {{ic|IN_CLOSE_WRITE}} is the action to watch for.  The third parameter {{ic|/usr/local/bin/efistub-update.sh}} is the script to execute.
{{hc|File: /etc/incron.d/efistub-update.conf|<nowiki>
/boot/initramfs-linux-fallback.img IN_CLOSE_WRITE /usr/local/bin/efistub-update.sh
Now just add {{ic|incrond}} to the daemon list in {{ic|/etc/rc.conf}} and it will automatically start up and copy the new files to the proper place every time the kernel is updated.
==== Sync EFISTUB Kernel in UEFISYS partition using Mkinitcpio hook ====
This uses a hook that spawns a background process, which waits for the generation process to finish, then copies the finished kernel and initrd.
This approach doesn't need a system level daemon to function.
{{hc|File: /usr/lib/initcpio/install/efistub-update|<nowiki>
#!/usr/bin/env bash
build() {
    local kernel= image=
    while getopts ':c:S:' OPT; do
        case $OPT in
        'c') kernel=$OPTARG;;
        'S') image=$OPTARG;;
    /root/watch.sh $image $kernel &
help() {
    cat <<HELPEOF
This hook simply waits for mkinitcpio to finish and copies the finished ramdisk and kernel to UEFI
# vim: set ft=sh ts=4 sw=4 et:
{{hc|File: /root/watch.sh|<nowiki>
while [[ -d "/proc/$PPID" ]]; do
    sleep 1
echo "Synced $INITRD to $EFI_DIR"
Then simply add {{ic|efistub-update}} to the list of hooks in {{ic|/etc/mkinitcpio.conf}}
=== Booting EFISTUB ===
There are various ways of booting EFISTUB kernels. Those described here are:
# Using rEFInd UEFI Boot Manager <-- Nice boot GUI.
# Using Gummiboot Boot Manager
# Using UEFI Shell
# Using efibootmgr entry <-- will load Arch Linux directly. No GUI.
==== Using rEFInd ====
rEFInd is a fork of rEFIt Boot Manager (used in Intel Macs) by Rod Smith (author of GPT-fdisk). rEFInd fixes many issues in rEFIt with respect to non-Mac UEFI booting and also has support for booting EFISTUB kernels and contains some features specific to them. More info about rEFInd support for EFISTUB is at http://www.rodsbooks.com/refind/linux.html .
Install the {{Pkg|refind-efi}} package from [extra]
# pacman -S refind-efi
Then run the below commands ($esp is the mountpoint of UEFISYS partition)
# mkdir -p $esp/EFI/refind
For 64-bit UEFI
# cp /usr/lib/refind/refindx64.efi $esp/EFI/refind/refindx64.efi
For 32-bit UEFI
# cp /usr/lib/refind/refindia32.efi $esp/EFI/refind/refindia32.efi
Common commands:
# cp /usr/lib/refind/config/refind.conf $esp/EFI/refind/refind.conf
# cp -r /usr/share/refind/icons $esp/EFI/refind/icons
Edit {{ic|$esp/EFI/refind/refind.conf}} according to your requirements. The file is well documented/commented. After that create {{ic|$esp/EFI/arch/refind_linux.conf}} as shown below (example):
"Boot with defaults" "root=PARTUUID=3518bb68-d01e-45c9-b973-0b5d918aae96 ro rootfstype=ext4 add_efi_memmap systemd.unit=graphical.target"
"Boot to Terminal"  "root=PARTUUID=3518bb68-d01e-45c9-b973-0b5d918aae96 ro rootfstype=ext4 add_efi_memmap systemd.unit=multi-user.target"</nowiki>}}
Please notice the difference between the standard UUID and the PARTUUID shown by {{ic|ls -l /dev/disk/by-partuuid/}}.
{{Note|{{ic|refind_linux.conf}} should be in the same directory as the kernel and initramfs files, not the directory {{ic|refindx64.efi}} resides.}}
These options are displayed as a submenu by rEFInd. The sub-menu can be accessed by using "+" or "insert" keys.
In non-Mac systems create an entry for rEFInd using [[UEFI#efibootmgr|efibootmgr]].
# modprobe efivars
# efibootmgr -c -g -d /dev/sdX -p Y -w -L "rEFInd" -l '\EFI\refind\refindx64.efi'
where {{ic|/dev/sdX}} is the drive and {{ic|Y}} is the partition number of UEFISYS in {{ic|/dev/sdXY}}.
In case of Apple Macs, try {{AUR|mactel-boot}} for an experimental "bless" utility for Linux. If that does not work, use "bless" form within OSX to set rEFInd as default bootloader. Assuming UEFISYS partition is mounted at {{ic|/mnt/efi}} within OSX, do
$ sudo bless --setBoot --folder /mnt/efi/EFI/refind --file /mnt/efi/EFI/refind/refindx64.efi
In case of VirtualBox, see [[VirtualBox#Using_Arch_under_Virtualbox_EFI_mode]].
==== Using gummiboot ====
[[Gummiboot]] is a UEFI Boot Manager which provides a nice menu for EFISTUB Kernels. It is a new program and relatively untested compared to rEFInd . It is available in [extra] as {{Pkg|gummiboot-efi}}. See http://freedesktop.org/wiki/Software/gummiboot for more info.
==== Using UEFI Shell ====
It is possible to launch EFISTUB kernel form UEFI Shell as if it is a normal UEFI application. In this case the kernel parameters are passed as normal parameters to the launched EFISTUB kernel file.
> fs0:
> cd \EFI\arch
> vmlinuz-arch.efi root=PARTUUID=3518bb68-d01e-45c9-b973-0b5d918aae96 ro rootfstype=ext4 add_efi_memmap initrd=\EFI\arch\initramfs-arch.img
==== Using efibootmgr entry ====
{{Note|1=This menthod may not work due to [https://git.kernel.org/?p=linux/kernel/git/mfleming/efi.git;a=commitdiff;h=b003aaf799c991295b8b73e8f940d20bda2c1bbb;hp=ddffeb8c4d0331609ef2581d84de4d763607bd37 limitations in how the kernel handles uefi runtime variables]. For example in Lenovo Thinkpads the initrd path is truncated (verified using {{ic|efibootmgr -v}} command) and therefore the kernel fails to boot.}}
{{Note|Some UEFI firmwares may not support embedding command line parameters to uefi applications in the boot entries.}}
It is possible to directly embed the kernel parameters within the boot entry created by efibootmgr. This means that in your BIOS/UEFI you will be able to select Arch Linux directly in the default boot order, and on startup it will boot into Arch directly without any kind of boot selection GUI.
Do (as root):
Install efibootmgr if you haven't already.
  # pacman -S --needed efibootmgr
Determine the UUID or PARTUUID of your boot device (ie. the partition for {{ic|/}}, not the EFI boot partition)
# blkid
Load the EFI module.
# modprobe efivars
Finally, add the efistub.
WARNING: Make sure you replace the following before running this command:
* ''3518bb68-d01e-45c9-b973-0b5d918aae96'' -- with the UUID of your {{ic|/}} partition. (This is not PARTUUID!)
* ''ext4'' -- if you use a different file system.
* ''/dev/sda'' -- the drive that contains the EFI boot partition.
* ''-p 1'' -- the partition number of the EFI boot partition.
# echo 'root=UUID=3518bb68-d01e-45c9-b973-0b5d918aae96 ro rootfstype=ext4 add_efi_memmap initrd=\EFI\arch\initramfs-arch.img' | iconv -f ascii -t ucs2 | efibootmgr -c -g -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -@ -
or you can just run the following line (remember to replace /dev/sda1):
# echo "root=UUID=$(blkid /dev/sda1 -o value -s UUID) ro rootfstype=ext4 add_efi_memmap initrd=\\EFI\\arch\\initramfs-arch.img" | iconv -f ascii -t ucs2 | efibootmgr -c -g -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -@ -
{{Note|The trailing hyphen after {{ic|--append-binary-args}} or {{ic|-@}} is required to instruct efibootmgr to read the parameters from STDIN (standard input). The code should be {{ic|--append-binary-args -}} or {{ic|-@ -}} .}}
More info about efibootmgr at [[UEFI#efibootmgr]]. Forum post https://bbs.archlinux.org/viewtopic.php?pid=1090040#p1090040 .
{{Note|Some firmwares may have trouble with the "initrd path" when piping in ucs-2 as shown above. In this case, one may put vmlinuz-linux.efi and the initramfs in the root of the ESP and adjust the efibootmgr entry accordingly.}}
== GRUB 2.x ==
GRUB 2.x contains its own filesystem drivers and does not rely on the firmware to access the files. It can directly read files from {{ic|/boot}} and does not require the kernel and initramfs files to be in the UEFISYS partition. Detailed information at [[GRUB#UEFI_systems_2]]. For bzr development version try AUR package - {{AUR|grub-efi-x86_64-bzr}}.
{{Note|Syslinux UEFI support is currently part of version 6.00-preXX or in firmware branch of upstream git repo. It is considered alpha quality by upstream. The below information is provided mainly to enable bug-testing. Please report all issues upstream.}}
{{Note|Syslinux UEFI can boot only those kernels that support '''EFI Handover Protocol'''. Thus LTS kernels are not supported.}}
Install {{AUR|syslinux-efi-git}} AUR package and copy {{ic|/usr/lib/syslinux/efi64/*}} to {{ic|$esp/EFI/syslinux/}} ({{ic|$esp}} is the mountpoint of UEFISYS partition) ({{ic|efi64}} is for x86_64 UEFI firmwares, replace with {{ic|efi32}} for i386 UEFI firmwares), and then create a boot entry using efibootmgr in the firmware boot manager.
== ELILO ==
ELILO is the UEFI version of LILO Boot Loader. It was originally created for Intel Itanium systems which supported only EFI (precursor to UEFI). It is the oldest UEFI bootloader for Linux. It is still in development but happens at a very slow pace. Upstream provided compiled binaries are available at http://sourceforge.net/projects/elilo/ . Elilo config file {{ic|elilo.conf}} is similar to [[LILO]]'s config file. AUR package - {{AUR|elilo-efi-x86_64}} (only for x86_64 UEFI).
EFILINUX is a reference implementation of a UEFI Linux bootloader and precursor to Kenrel EFISTUB support. It is considered to be a alpha quality software (as on 16-MAY-2012). Upstream sources are at https://github.com/mfleming/efilinux . and the usage instructions are at http://thread.gmane.org/gmane.linux.kernel/1172645 and http://article.gmane.org/gmane.linux.kernel/1175060 . AUR packages - {{Pkg|efilinux-efi}} and {{AUR|efilinux-efi-x86_64-git}} (only for x86_64 UEFI).
== Package Naming Guidelines ==
UEFI bootloader package(s) should be suffixed with {{ic|-efi-x86_64}} or {{ic|-efi-i386}} to denote package built for 64-bit and 32-bit UEFI respectively. If a single package contains both 64-bit and 32-bit UEFI applications, then {{ic|-efi}} suffix should be used in the '''pkgname'''.
== See also ==
* [http://www.rodsbooks.com/efi-bootloaders/ Rod Smith - Managing EFI Boot Loaders for Linux]
* [http://www.rodsbooks.com/refind/ Rod Smith - rEFInd, a fork or rEFIt]
* [https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob_plain;f=Documentation/x86/efi-stub.txt;hb=HEAD Linux Kernel Documentation on EFISTUB]
* [http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=291f36325f9f252bd76ef5f603995f37e453fc60;hp=55839d515495e766605d7aaabd9c2758370a8d27 Linux Kernel EFISTUB Git Commit]
* [http://www.rodsbooks.com/efi-bootloaders/efistub.html Rod Smith's page on EFISTUB]
* [http://www.rodsbooks.com/refind/linux.html rEFInd Documentation for booting EFISTUB Kernels]

Latest revision as of 15:28, 7 October 2018

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