Ubuntu kernel configuration

Michael J. Lynch mlynch at gcom.com
Wed Sep 14 13:18:40 UTC 2005

crimsun at fungus.sh.nu wrote:
> On Tue, Sep 13, 2005 at 03:29:25PM -0700, Kevin O'Gorman wrote:
>>I looked in /proc, but the config was not there (as it is in my other Linux
> /boot/config-$(uname -r)

Ok...I'm going to chime in here on this.  A couple of people here
at our company have been struggling with this for a few weeks now
and have not found the answer.  First let me preface this by saying
that one of the people working on this has been developing linux
kernel code for the past 20 years so he is intimately familiar
with the build process.

Anyway...what we've found is that the "/boot/config-$(uname -r)"
files can NOT be used to recreate the "/boot/vmlinux-$(uname -r)" and
"/boot/initrd.img-$(uname -r)" files.

The process we've been using (the same as what we use with severl
other distros) is:

	copy /boot/config-$(uname -r)
		to /usr/src/linux-$(uname -r)/.config
	In /usr/src/linux-$(uname -r) run "make oldconfig"
	Do remainder of build process

We always end up with vmlinuz and initrd images that a significantly
different that the originals.  The *big* problem is that initrd ends
up being huge and wont fit in memory (256M).  The original initrd that
was supposedly generated using the config is tiny in comparison.  If
we look at the config, practically *everything* is being compiled as
modules.  This explains why initrd is so large.  So far we have not
been able to find a config that can be used to re-create a distributed

Is there something we are doing incorrectly here or is there some
Ubuntu specific step we are missing?  All we are really interested in
doing is creating a kernel and initrd that, with the exception of
enabling kernel debugging, matches the distributed kernel.

Any tips or pointers would be greatly appreciated.

Michael J. Lynch

What if the hokey pokey IS what it's all about -- author unknown

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