[CentOS-devel] Kernel used on installation media.

Sat Feb 24 10:55:15 UTC 2007
Johnny Hughes <mailing-lists at hughesjr.com>

On Fri, 2007-02-23 at 16:18 -0800, Ray Van Dolson wrote:
> On Sat, Feb 24, 2007 at 12:06:03AM +0000, Karanbir Singh wrote:
> > Ray Van Dolson wrote:
> > >Hi all, I hope this is not too off topic.  I've searched the -devel 
> > >archives,
> > >but haven't found clear-cut information on this, so thought I'd ask.
> > >
> > >I am trying to determine the kernel configuration used to build the kernel
> > >used on the installation media (CD #1 or the vmlinuz/initrd.img files in 
> > >their
> > >respective images/boot.iso or images/diskboot.img files).
> > >
> > >My guess is the kernel configurations are not identical to the ones 
> > >ultimately
> > >used to build the kernels used on the system once it is up and running....
> > >
> > >I ask because I am interested in rebuilding the kernel used on CD #1 to 
> > >boot
> > >into the installer.
> > >
> > 
> > look in the distro tree : 
> > http://mirror.centos.org/centos/4/os/i386/CentOS/RPMS ( eg, for the i386  )
> > the kernel-2.6.9-*.<i686|i586>.rpm are the ones used for the installer, 
> > each contain a .config file which will give you the config file used at 
> > build time for that kernel rpm.
> 
> K, so just the same kernel then that's used on the OS.  That makes it fairly
> straightforward.
> 
> > Why do you need to rebuild the installer kernel ? doing DriverDisks for 
> > some piece of non-supported-by-default-hardware isnt hard.
> 
> Well, the driver is an updated ata_piix and libsata driver for the ICH8
> chipset.  Neither Intel nor Dell appears to have a driver for download on
> their page.
> 
> jbaron's beta release of the -48 kernel for RHEL4 includes driver support for
> it, but obviously the .ko's in his kernel are for the -48 kernel.  I would
> either have to backport the driver to the kernel used on the U4/CentOS install
> CD's or update the kernel on those CD's to be -48 and work with the new
> drivers out of the box.
> 
> I haven't taken a stab at backporting these drivers into the current stable
> kernels (and kernel used on the boot CD), maybe that would be easier...

Just for the record ... the ko's will work across kernels because they
can be inserted by just doing depmod -a as long as the are built by the
same major gcc (3.4) and this is the same major kernel (2.6.9) and the
same type (normal, smp, hughmem, largesmp).

BUT .. you really need to rebuild the initrd that does the isntall to,
as well as use that newer kernel (there are going to most likely be
pieces missing in the older kernel that the new module needs) ... but
who knows, you might get lucky :P
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