#acl PaulHowarth:read,write,admin,revert,delete All:read

= Building a Custom Kernel RPM Package =

This HOWTO is based on Kevin Hobbs' tutorial at
http://oak.cats.ohiou.edu/~hobbsk/kernel-compilation-tutorial-en/index.html

The process was tested using Fedora Core 4 but may also work for other Fedora/Red Hat-based distributions.

== Create RPM Build Environment ==

If you have not built RPM packages using your regular user account (not root) before, you should
[[CreateRPMBuildEnvironment|create an RPM build environment]] for your account before going any further.

== Download the Source ==

Download the `kernel-nnn.src.rpm` from the SRPMS directory of your favourite Fedora mirror:
{{{

$ wget http://download.fedora.redhat.com/pub/fedora/linux/core/updates/4/SRPMS/kernel-2.6.15-1.1831_FC4.src.rpm
--12:08:40--  http://download.fedora.redhat.com/pub/fedora/linux/core/updates/4/SRPMS/kernel-2.6.15-1.1831_FC4.src.rpm
           => `kernel-2.6.15-1.1831_FC4.src.rpm'
Resolving download.fedora.redhat.com... 66.187.224.20, 209.132.176.20, 209.132.176.220, ...
Connecting to download.fedora.redhat.com|66.187.224.20|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 41,178,693 (39M) [application/x-rpm]

100%[===============================================================================>] 41,178,693   115.21K/s    ETA 00:00

12:13:27 (140.38 KB/s) - `kernel-2.6.15-1.1831_FC4.src.rpm' saved [41178693/41178693]
}}}

== Install the Source ==

Use `rpm` to install the kernel source code:
{{{

$ rpm -Uvh kernel-2.6.15-1.1831_FC4.src.rpm
   1:kernel                 ########################################### [100%]}}}

== Disable SMP Build (Optional) ==

If a multi-processor kernel is not needed, edit `~/rpmbuild/SPECS/kernel-2.6.spec` to disable the smp build.
This step saves time and disk space.
{{{

%define buildsmp 0}}}
			
== Prepare Build ==

Use the `rpmbuild` prep stage to apply any patches and configure the kernel exactly as it is in the Fedora distribution:
{{{

$ rpmbuild -bp --target=$(arch) ~/rpmbuild/SPECS/kernel-2.6.spec
Building target platforms: i686
Building for target i686
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.99618
+ umask 022
+ cd /home/phowarth/rpmbuild/BUILD
+ LANG=C
+ export LANG
+ unset DISPLAY
+ '[' '!' -d kernel-2.6.15/vanilla ']'
+ cd /home/phowarth/rpmbuild/BUILD
+ rm -rf kernel-2.6.15
+ /bin/mkdir -p kernel-2.6.15
+ cd kernel-2.6.15
+ /usr/bin/bzip2 -dc /home/phowarth/rpmbuild/SOURCES/linux-2.6.15.tar.bz2
+ tar -xf -
...
+ echo '# i386'
+ cat .config
+ perl -p -i -e 's/^SUBLEVEL.*/SUBLEVEL = 15/' Makefile
+ perl -p -i -e 's/^EXTRAVERSION.*/EXTRAVERSION = -prep/' Makefile
+ find . -name '*.orig' -o -name '*~' -exec rm -f '{}' ';'
+ exit 0}}}

== Reconfigure the kernel ==

Use one of the kernel configuration interfaces to make changes to the kernel configuration.
Since the entire source tree, including `.config`, will be overwritten before the actual build,
you need to copy `.config` to the rpm source directory, replacing the original configuration for your architecture.
In fact, you actually need to add make a small edit to the `.config` file, adding a comment line at the top of the file to specify the base architecture for your kernel:
{{{

$ cd ~/rpmbuild/BUILD/kernel-2.6.15/linux-2.6.15/
$ make menuconfig
$ (echo "# $(uname -i)"; cat .config) > ~/rpmbuild/SOURCES/kernel-2.6.15-$(arch).config
$ cd ~}}}		
{i} Some of the configuration interfaces require other packages, e.g. `menuconfig` requires `ncurses-devel`, `xmenu` requires `qt-devel`, and `gmenu` requires `gtk2-devel`.

== Build the Kernel ==

The `-bb` option to `rpmbuild` will build the kernel binary package,
performing every rpm build stage along the way but with the new configuration:
{{{

$ rpmbuild -bb --target=$(arch) ~/rpmbuild/SPECS/kernel-2.6.spec
Building target platforms: i686
Building for target i686
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.38044
+ umask 022
+ cd /home/phowarth/rpmbuild/BUILD
+ LANG=C
+ export LANG
+ unset DISPLAY
+ '[' '!' -d kernel-2.6.15/vanilla ']'
+ cd kernel-2.6.15
+ mv linux-2.6.15 deleteme
+ rm -rf deleteme
+ cp -rl vanilla linux-2.6.15
...
+ /usr/lib/rpm/redhat/brp-compress
+ /usr/lib/rpm/redhat/brp-strip-static-archive /usr/bin/strip
+ /usr/lib/rpm/redhat/brp-strip-comment-note /usr/bin/strip /usr/bin/objdump
Processing files: kernel-2.6.15-1.1831_FC4.phowarth
Processing files: kernel-devel-2.6.15-1.1831_FC4.phowarth
Processing files: kernel-debuginfo-2.6.15-1.1831_FC4.phowarth
Requires(rpmlib): rpmlib(CompressedFileNames) <= 3.0.4-1 rpmlib(PayloadFilesHavePrefix) <= 4.0-1
Checking for unpackaged file(s): /usr/lib/rpm/check-files /home/paul/tmp/kernel-2.6.15-1.1831_FC4.phowarth-root
Wrote: /home/phowarth/rpmbuild/RPMS/i686/kernel-2.6.15-1.1831_FC4.phowarth.i686.rpm
Wrote: /home/phowarth/rpmbuild/RPMS/i686/kernel-devel-2.6.15-1.1831_FC4.phowarth.i686.rpm
Wrote: /home/phowarth/rpmbuild/RPMS/i686/kernel-debuginfo-2.6.15-1.1831_FC4.phowarth.i686.rpm
Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.61179
+ umask 022
+ cd /home/phowarth/rpmbuild/BUILD
+ cd kernel-2.6.15
+ rm -rf /var/tmp/kernel-2.6.15-1.1831_FC4.phowarth-root
+ exit 0}}}		
{i} The option `-ba` should be used (instead of `-bb`) to also make a source rpm if the new kernel will be distributed.

== Install the Kernel RPM ==

Install the kernel rpm. Do not upgrade or otherwise replace a working kernel:
{{{

$ sudo rpm -ihv ~/rpmbuild/RPMS/$(arch)/kernel-2.6.15-1.1831_FC4.phowarth.$(arch).rpm
Preparing...                ########################################### [100%]
   1:kernel                 ########################################### [100%]}}}
{i} This is the only time root privileges are required.

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