Kernels/Arch Build System

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Revision as of 15:12, 29 September 2012 by Oskude (Talk | contribs) (put Changing build() back)

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The Arch Build System can be used to build a custom kernel based on the official linux package. This compilation method can automate the entire process, and is based on a very well tested package. You can edit the PKGBUILD to use a custom kernel configuration or add additional patches.

Getting the Ingredients

# pacman -S abs base-devel

First of all, you need a clean kernel to start your customization from. Fetch the kernel package files from ABS:

$ ABSROOT=. abs core/linux

Then, get any other file you need (e.g. custom configuration files, patches, etc.) from the respective sources.

Modifying the PKGBUILD

Modify pkgbase=linux for your custom package name.

Changing build()

You probably need a custom .config file for your kernel. You can uncomment one of the possibilities shown in the build() function of the PKGBUILD, e.g.:

PKGBUILD
...
  # load configuration
  # Configure the kernel. Replace the line below with one of your choice.
  #make menuconfig # CLI menu for configuration
  make nconfig # new CLI menu for configuration
  #make xconfig # X-based configuration
  #make oldconfig # using old config from previous kernel version
  # ... or manually edit .config
...

If you have already a kernel config file, I suggest to uncomment one interactive config tool, such as nconfig, and load your config from there. This avoids problems with kernel naming I have met with other methods.

Note: If you uncomment return 1, you can change to the kernel source directory after makepkg finishes extraction and then make nconfig. This lets you configure the kernel over multiple sessions. When you're ready to compile, copy the .config file over top of either config or config.x86_64 (depending on your architecture), comment return 1 and use makepkg -i. But not use this for custom patch, put you patch commands after these lines. If you do patch manually bztar unpack and replace your patch.

Compiling

Tip: Running compilation jobs simultaneously can reduce compilation time significantly on multi-core systems.

You can now proceed to compile you kernel by the usual command makepkg If you have chosen an interactive program for configuring the kernel parameters (like menuconfig), you need to be there during the compilation.

Note: A kernel needs some time to be compiled. 1h is not unusual.

Installing

After the makepkg, you can have a look at the linux.install file. You will see that some variables have changed. Now, you only have to install the package as usual with pacman (or equivalent program):

# pacman -U <kernel_package>

Boot Loader

Now, the folders and files for your custom kernel have been created, e.g. /boot/vmlinuz-linux-test. To test your kernel, update your bootloader (/boot/grub/menu.lst for GRUB) and add new entries ('default' and 'fallback') for your custom kernel. That way, you can have both the stock kernel and the custom one to choose from.