[CentOS] newbie kernel question

Sat Apr 1 23:30:59 UTC 2006
Jim Perrin <jperrin at gmail.com>

> Everybody should want to recompile the kernel, if not
> for the experience, but for removing the bloat.  Does
> everybody really need every chipset compiled in the
> kernel!

Uh, that's the beauty of building modules. You only load what you
need. And the rhel/centos kernel is almost entirely modular.

If the degree of dificulty of building a
> custom kernel on Centos change from the traditional
> method (make clean, make mrproper, make xconfig, etc)
> than say so, and point to an authoritative howto
> guide, if there is any.

The idea behind the EL kernel is that it's a stable, reliable, and can
be duplicated quickly and reliably across multiple machines and
environments. To some non-trivial extent it's also so that there's
someone ELSE to blame if it doesn't work. For some reason, employers
and corporations love to pay people for support rather than rely on
the merits of their tech staff. Keep in mind the nearly 700 patches
that are in the EL kernel source rpm. Red Hat has basically stated
that if you build your own kernel, you're on your own to support it,
and as such, they're not producing documentation on how to build your
own. It's not just RHEL and CentOS moving this way. Mandriva, SuSE,
and to an extent, Debian and Ubuntu are also like this.

> But whatever you do please
> don't insult by deciding for 98% of us what is and
> what is not "something you really want to do".  I can
> only speak for myself, and I really want to be able to
> recompile the Centos kernel, otherwise I wouldn't
> waste my energy  asking a zillion times how to compile
> Centos' kernel.

This has already been decided, and it's not an insult to you. How do
you make a distribution easy to use, AND support kernel rebuilds? Is
your mother or grandfather capable of rebuilding a kernel? Can they do
it better than the RHEL developers who do it for a living? It's not an
insult. It's a choice in ease of use vs support vs cost. If you're
smart enough to rebuild the kernel, you're completely welcome to.

> Second irony (from second hand information) is that
> the vanila kernel compile just fine on Centos using
> the traditional method.

It does, but it's not the proper method for several reasons. Vanilla
kernel source will also work on centos, but it's not something we
recommend, and if you break it, you get to keep the pieces. The people
who want to rebuild everything aren't the people in our target
audience. They're in Gentoo's target audience.

Now, to the information you wanted. There is a blog done by BJS which
described the method, although I have misplaced the link. There is no
official or otherwise documentation, because it's not something we
actively support or recommend. Not to stop you, but for the simple
logic of -> why waste time documenting something you aren't supporting
when you can document the things you do support instead?

If you search the late March list archive from the last week or so, I
did a very brief walkthrough of how the rebuilding is actually done.
You're welcome to read through that and see if it helps.

If it doesn't.. .keep in mind that rebuilding the kernel isn't
supported, and we've provided a kernel with the feature you claim to
want. If you REALLY want to rebuild stuff and get your hands dirty for
the experience, check out gentoo or LFS.

Any sufficiently advanced technology is indistinguishable from magic.
-Arthur C. Clarke