KernelCustomBuild
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| == Disclaimer == | The Kernel build documentation has moved to https://help.ubuntu.com/community/Kernel/Compile |
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| Build or using custom kernels will pretty much lose any ability to get support for your system. You will not be allowed to file bugs on the custom built kernel (if you do, they will be Rejected without explanation). | Please update any bookmarks or links pointing to this page. |
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| If you have a commercial support contract with Ubuntu/Canonical, this will void such support. | This page is now used for comments, questions and discussion. |
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| Also note that this page describes how to do things for the edgy (2.6.17) kernel and newer! Until this kernel source, we did not have in place any mechanisms that would allow people to build their own kernels easily. This was intentional. | == Comments == '''Q:''' What about custom install and netboot images (and their initrd etc)?, PeterMagnusson |
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| This page does '''NOT''' describe how to build stock kernels from kernel.org. This is how to rebuild the actual Ubuntu kernel source. | '''A:''' Take a look at the Debian Installer instructions for this: http://wiki.debian.org/DebianInstaller/Modify/CustomKernel Although I haven't tried these instructions yet, and they might not quite work with the current Ubuntu Way, they look fairly comprehensive and should at least be a step in the right direction. (MatthewPalmer) |
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| == Reasons for compiling a custom kernel == | '''Q:''' What directory are you in when you run these commands ls -l debian/config/i386/ I'm sure you mean to untar the kernel source you just downloaded and cd into that tree (cd /usr/src ; tar xf linux-source-2.6.17.tar.bz2 ; cd linux-source-2.6.17) but there is no directory debian/config/i386 in there. debian/Config has .config files in it, but no bigiron file so i dono where that kernel comes from? EliCriffield |
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| * You are a kernel developer. * You need the kernel compiled in a special way, that the official kernel cannot be compiled in (for example, with some experimental feature enabled). * You are attempting to debug a problem for which you have or will file a bug report on the stock Ubuntu kernel. |
'''A:''' Maybe he meant debian/Config? '''A2:''' On 6.06, the linux-source package does not include the debian directory, it seems. You need to install the source package for linux-image, with a command like sudo apt-get source linux-image-2.6.15-27-386 SteveEdmondson '''Q:''' Is there any way to get a kernel build faster? I would like to do some "light" kernel hacking. What are the easy steps to just compile a kernel image? * you can try using make-kpkg, the standard debian kernel-building tool. There are lots of guides around, hopefully the net person to read this page will have more time and put in a link. * http://newbiedoc.sourceforge.net/system/kernel-pkg.html '''Q:''' What is Ubuntu's default kernel config? The kernel doesn't put anything in /proc/config. * like all debian-based system, ubuntu's kernel puts the config in {{{ /boot/config-`uname -r` }}} |
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| == Reasons for NOT compiling a custom kernel == | '''Q:''' Maybe that's not the right place to ask, but I am stuck... I am trying to compile a vanilla kernel (to test an issue with suspend/resume). I do not want to use the make-kpkg method --- too slow on recompiles. So I can compile the kernel, install modules, and then I make the initrd.img with the update-initramfs thing... and all seems to work, but the new kernel simply boots on a BusyBox and does not boot the system. How do I build an initramfs image equivalent to the standard ubuntu one? RomanoGiannetti2 * Well, auto-answering. update-initramfs '''do''' work. I was bitten by this bug: http://lists.debian.org/debian-kernel/2006/07/msg00427.html which seems to still exists. Call update-initramfs with -v and it will fail. |
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| * You merely need to compile a special driver. For this, you only need to install the linux-headers packages. * You have no idea what you are doing, and if you break something, you'll need help fixing it. If you hose your box, reinstall. Don't bother asking for help. * You got to this page by mistake, but checked it out because it looked interesting. Believe me, this isn't interesting at all :) |
'''Q:''' What is the correct way to add 'lib/firmware/<custom-kernel>' to a custom kernel .deb so that the kernel and firmware can be distributed together? '''Q:''' Where do the firmware images from the generic kernel come from - (ie which package?) - or how does one get them so one can build a generic kernel? It would be useful if this was explained somewhere. I found that the system didn't recover very easily from errors and unsuccessful builds, and that the debian/rules "clean" target didn't always want to clean up, so I had to reinstall the source several times. It may be possible to redesign the debian/rules script to make it easier for non-devs to use. If I learn enough about Makefiles I will make an effort to do that... '''Q:''' Where can I find the .config file for the \casper\ live cd 7.04 kernel RichardWarwick '''Q:''' The page gives a stern warning against building kernels just to customize a driver. Could we please have some other page with step-by-step instructions for customizing a driver. E.G. adding a device ID to usbserial? BensonMargulies2 '''A/Q:''' I recently had to build a kernel with the same version names just so I could basically load a serial PCI module the kernel maintainers won't patch and this also required I include a new kernel because the module is built into kernel instead of being a module. I agree, it is a really crappy way to do it but this is the only way I know which still lets all the Ubuntu repository packages still keep on keeping on. They still think it's the regular Ubuntu kernel. It is, with the exception of one darn PCI module. For what it's worth, here's the batch file of all this entailed: *sudo apt-get build-dep linux-source-2.6.22 fakeroot *sudo apt-get source linux-image-2.6.22-14-generic *cd linux-source-2.6.22-2.6.22/ *# PATCH YOUR MODULE(s) SOURCE *sudo cp /boot/config-2.6.22-14-generic .config *# MAKE SMALL CHANGES TO THE KERNEL CONIFG IF NEEDED *sudo make menuconfig *cat /proc/version *# notice the -14-generic part of the version and use this in the Makefile: EXTRAVERSION = -14 *sudo vi Makefile *sudo make-kpkg --rootcmd fakeroot --initrd --append-to-version=-generic kernel-image *sudo cp arch/i386/boot/bzImage /boot/bzImage-2.6.22-14-generic *sudo cp YOUR-MODULE.ko to /lib/module/2.6.22-14-generic/kernel/MODULE-LOCATION/MODULE-NAME.ko *# copy the default grub menu item and change the vmlinuz.... kernel to use bzImage..... *sudo vi /boot/grub/menu.lst Q:Is there a better way and is there a way to just build modules instead of the whole kernel and all modules? '''Q:''' When I try to run "debian/scripts/misc/oldconfig" I get the error: "bash: debian/scripts/misc/oldconfig: Permission denied" I get a similar error with debian/scripts/misc/splitconfig.pl This is easy to workaround with "chmod +x debian/scripts/misc/oldconfig". However, is this a bug or an error in the doc, or ...? '''Q:''' The linux-image-2.6.24-7-generic.deb is only 68MB, but my custom built kernel linux-image-2.6.24.3-kml-kml_2.6.24-16.30_i386.deb is 198MB. All I did was add the Kernel Mode Linux patch, and disable Paravirtualisation. Why would it be so large? Also when I try to install the deb it [http://www.csse.uwa.edu.au/~john/bugs/InstallCustomKernel claims] it cannot find "/lib/firmware/2.6.24.3-kml-kml"; why? |
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| == What you'll need == To start, you will need to install a few packages. Luckily, all of them can be installed at once using a single meta-package: {{{ sudo apt-get install linux-kernel-devel }}} This will install the compiler and related packages. It will also install the git-core package, which is the best way to interact with the Ubuntu kernel source. == How to get the kernel source == There are two ways to obtain the Ubuntu kernel source. The most prefered way it to use git. Detailed instructions for using git can be found in KernelGitGuide. The other way is to simply: {{{ sudo apt-get install linux-source-2.6.17 }}} However, this will almost always be out of date. Using git allows you to always stay in sync with the latest Ubuntu kernel source. == Modifying the source for your needs == For most people, simply modifying the configs is enough. If you need to install a patch, read the instructions from the patch provider for how to apply. The stock Ubuntu configs are located in ''debian/config/ARCH/'' where ARCH is the architecture you are building for. In this directory are several files. The ''config'' file is the base for all targets in that architecture. Then there are several config.FLAVOUR files that contain options specific to that target. For example, here are the files for 2.6.17, i386: {{{ $ ls -l debian/config/i386/ total 88 -rw-r--r-- 1 me me 62737 Jun 14 18:31 config -rw-r--r-- 1 me me 1859 Jun 12 14:59 config.386 -rw-r--r-- 1 me me 1394 Jun 12 14:59 config.686 -rw-r--r-- 1 me me 1420 Jun 12 14:59 config.k7 -rw-r--r-- 1 me me 1519 Jun 12 14:59 config.server -rw-r--r-- 1 me me 1867 Jun 12 14:59 config.server-bigiron }}} If you need to change a config option, simply modify the file that contains the option. If you modify just the ''config'' file, it will affect all targets for this architecture. If you modify one of the target files, it only affects that target. == Building the kernel == To build the kernel(s) is very simple. Depending on your needs, you may want to build all the kernel targets, or just one specific to your system. However, you also want to make sure that you do not clash with the stock kernels. Use this command to build all targets for the architecture you are buidling on: {{{ AUTOBUILD=1 fakeroot debian/rules binary-debs }}} The ''AUTOBUILD'' environment variable triggers special features in the kernel build. First, it skips normal ABI checks (ABI is the binary compatibility). It can do this because it also creates a unique ABI ID. If you used a git repo, this unique ID is generated for the git HEAD SHA. If not, it is generated from the uuidgen program. Your packages will be named using this ID. To build a specific target, use this command: {{{ AUTOBUILD=1 fakeroot debian/rules binary-debs flavours=k7 }}} This will only build the AMD k7 variant of the i386 architecture. == When it's done == Now that the build is complete, you can install the generated deb's using dpkg: {{{ sudo dpkg -i linux-image-2.6.17-2-ef427c-k7_2.6.17-2.2_i386.deb sudo dpkg -i linux-headers--2.6.17-2-ef427c-k7_2.6.17-2.2_i386.deb }}} If you use modules from ''linux-restricted-modules'', you will need to recompile this against your new linux-headers package. Details on how to do this will be added later. |
The Kernel build documentation has moved to https://help.ubuntu.com/community/Kernel/Compile
Please update any bookmarks or links pointing to this page.
This page is now used for comments, questions and discussion.
Comments
Q: What about custom install and netboot images (and their initrd etc)?, PeterMagnusson
A: Take a look at the Debian Installer instructions for this: http://wiki.debian.org/DebianInstaller/Modify/CustomKernel Although I haven't tried these instructions yet, and they might not quite work with the current Ubuntu Way, they look fairly comprehensive and should at least be a step in the right direction. (MatthewPalmer)
Q: What directory are you in when you run these commands ls -l debian/config/i386/ I'm sure you mean to untar the kernel source you just downloaded and cd into that tree (cd /usr/src ; tar xf linux-source-2.6.17.tar.bz2 ; cd linux-source-2.6.17) but there is no directory debian/config/i386 in there. debian/Config has .config files in it, but no bigiron file so i dono where that kernel comes from? EliCriffield
A: Maybe he meant debian/Config?
A2: On 6.06, the linux-source package does not include the debian directory, it seems. You need to install the source package for linux-image, with a command like
sudo apt-get source linux-image-2.6.15-27-386
Q: Is there any way to get a kernel build faster? I would like to do some "light" kernel hacking. What are the easy steps to just compile a kernel image?
- you can try using make-kpkg, the standard debian kernel-building tool. There are lots of guides around, hopefully the net person to read this page will have more time and put in a link.
Q: What is Ubuntu's default kernel config? The kernel doesn't put anything in /proc/config.
like all debian-based system, ubuntu's kernel puts the config in /boot/config-`uname -r`
Q: Maybe that's not the right place to ask, but I am stuck... I am trying to compile a vanilla kernel (to test an issue with suspend/resume). I do not want to use the make-kpkg method --- too slow on recompiles. So I can compile the kernel, install modules, and then I make the initrd.img with the update-initramfs thing... and all seems to work, but the new kernel simply boots on a BusyBox and does not boot the system. How do I build an initramfs image equivalent to the standard ubuntu one? RomanoGiannetti2
Well, auto-answering. update-initramfs do work. I was bitten by this bug:
http://lists.debian.org/debian-kernel/2006/07/msg00427.html which seems to still exists. Call update-initramfs with -v and it will fail.
Q: What is the correct way to add 'lib/firmware/<custom-kernel>' to a custom kernel .deb so that the kernel and firmware can be distributed together?
Q: Where do the firmware images from the generic kernel come from - (ie which package?) - or how does one get them so one can build a generic kernel? It would be useful if this was explained somewhere.
I found that the system didn't recover very easily from errors and unsuccessful builds, and that the debian/rules "clean" target didn't always want to clean up, so I had to reinstall the source several times. It may be possible to redesign the debian/rules script to make it easier for non-devs to use. If I learn enough about Makefiles I will make an effort to do that...
Q: Where can I find the .config file for the \casper\ live cd 7.04 kernel RichardWarwick
Q: The page gives a stern warning against building kernels just to customize a driver. Could we please have some other page with step-by-step instructions for customizing a driver. E.G. adding a device ID to usbserial? BensonMargulies2
A/Q: I recently had to build a kernel with the same version names just so I could basically load a serial PCI module the kernel maintainers won't patch and this also required I include a new kernel because the module is built into kernel instead of being a module. I agree, it is a really crappy way to do it but this is the only way I know which still lets all the Ubuntu repository packages still keep on keeping on. They still think it's the regular Ubuntu kernel. It is, with the exception of one darn PCI module. For what it's worth, here's the batch file of all this entailed:
- sudo apt-get build-dep linux-source-2.6.22 fakeroot
- sudo apt-get source linux-image-2.6.22-14-generic
- cd linux-source-2.6.22-2.6.22/
- # PATCH YOUR MODULE(s) SOURCE
- sudo cp /boot/config-2.6.22-14-generic .config
- # MAKE SMALL CHANGES TO THE KERNEL CONIFG IF NEEDED
- sudo make menuconfig
- cat /proc/version
- # notice the -14-generic part of the version and use this in the Makefile: EXTRAVERSION = -14
- sudo vi Makefile
- sudo make-kpkg --rootcmd fakeroot --initrd --append-to-version=-generic kernel-image
- sudo cp arch/i386/boot/bzImage /boot/bzImage-2.6.22-14-generic
- sudo cp YOUR-MODULE.ko to /lib/module/2.6.22-14-generic/kernel/MODULE-LOCATION/MODULE-NAME.ko
- # copy the default grub menu item and change the vmlinuz.... kernel to use bzImage.....
- sudo vi /boot/grub/menu.lst
Q:Is there a better way and is there a way to just build modules instead of the whole kernel and all modules?
Q: When I try to run "debian/scripts/misc/oldconfig" I get the error: "bash: debian/scripts/misc/oldconfig: Permission denied" I get a similar error with debian/scripts/misc/splitconfig.pl This is easy to workaround with "chmod +x debian/scripts/misc/oldconfig". However, is this a bug or an error in the doc, or ...?
Q: The linux-image-2.6.24-7-generic.deb is only 68MB, but my custom built kernel linux-image-2.6.24.3-kml-kml_2.6.24-16.30_i386.deb is 198MB. All I did was add the Kernel Mode Linux patch, and disable Paravirtualisation. Why would it be so large? Also when I try to install the deb it [http://www.csse.uwa.edu.au/~john/bugs/InstallCustomKernel claims] it cannot find "/lib/firmware/2.6.24.3-kml-kml"; why?
KernelCustomBuild (last edited 2011-03-13 19:14:33 by 84-73-137-162)