Building CentOS-5 i586 Kernel

Currently the CentOS-5 kernel SRPM do not support i586 targets. This article provides instructions on modifying the official CentOS-5 kernel source and building an i586 kernel RPM out of it.

1. Unpack kernel source

Follow Section 2 of I Need the Kernel Source to unpack the kernel source into a working directory.

2. Patch specification file

Make the following changes to ~/rpmbuild/SPECS/kernel-2.6.spec:

1. Use a custom build ID to avoid conflict with official kernel by uncommenting the following line and defining a unique ID:

   %define buildid .your_identifier

2. Make i586 a valid target architecture by replacing the following lines:

   # Don't build 586 kernels for RHEL builds.
   %if 0%{?rhel}
   %define all_x86 i386 i686
   # we differ here b/c of the reloc patches
   %ifarch i686 x86_64

   with:

   %if 0%{?rhel}
   %define all_x86 i386 i586 i686
   # we differ here b/c of the reloc patches
   %ifarch i586 i686 x86_64

3. Prevent deletion of the i586 config file in the build process by removing these lines:

   # don't need these in general
   rm -f kernel-%{kversion}-i586.config

3. Update config file

Copy ~/rpmbuild/SOURCES/kernel-2.6.18-i686.config to ~/rpmbuild/SOURCES/kernel-2.6.18-i586.config and make the following changes in kernel-2.6.18-i586.config:

1. Replace the following lines:

   # CONFIG_M586 is not set
   # CONFIG_M586TSC is not set
   # CONFIG_M586MMX is not set
   CONFIG_M686=y

   with:

   CONFIG_M586=y
   # CONFIG_M586TSC is not set
   # CONFIG_M586MMX is not set
   # CONFIG_M686 is not set

4. Building the i586 kernel

Follow Section 5 of Custom Kernel to build the kernel. Use the --target=i586 flag to specify the desired architecture.