[CentOS] building a new kernel, problems booting without initrd

[Johnny Hughes]

On Sun, 2005-12-11 at 20:53 -0800, Richard Hubbell wrote:
> Thanks Jim.
> I have a need, but if it won't work, it won't work.  I may switch distribs
> if CentOS kernel is inextricably intertwined with the rest of the bits.
> 
> FWIW I don't need/want selinux and can get by without nptl if it
> proves troublesome. The kernel also has way too much stuff in
> it that I don't need, etc., etc.
> 
> The link you mention is broken.
> Dunno what gentoo's about so no comment there.
Don't take Jim's post to be negative (or mine either).

The problem is that the Kernel and GLIBC are the pieces that everything
else is built on ... and they are built to work together.

People think they are smarter than the paid developers at RH and they
want to build a kernel that doesn't have stuff they don't need ... but
that is not really required anymore.

With the adoption of modular kernels and initrd, you can dynamically
load the items that you need and remove the ones that you don't, and
lots of people get paid lots of money to make it happen right.  So, we
see a lot of people who mess up their systems because:

1.  They want the latest and greatest kernel ... (CentOS is enterprise
and therefore not latest and greatest)

2.  They want to remove items from their kernel ... (That don't load
anyway if they don't have a need, as they are kernel modules).

---------------
Now, if that is not you, then I apologize. But CentOS is painstakingly
rebuilt to mirror the binaries of an upstream vendor so that it works
exactly like that product ... and changing major bits of it (like kernel
or glibc) changes the whole distro.

Also. there are literally thousands of RH specific patches in the
kernel.
 
> 
> 
> On 12/11/05, Jim Perrin <jperrin at gmail.com> wrote:
> > On 12/11/05, Richard Hubbell <richard.hubbell at gmail.com> wrote:
> > > Hello all,
> > >
> > > Grabbed a new kernel (from kernel.org) to build a custom kernel
> > > but it won't boot.  I followed the directions at redhat to setup a box without
> > > initrd (which I don't want and don't need to use). But the system hangs.
> > > Has anyone built a custom kernel without using initrd? I'm using CentOS 4.2.
> > > It hangs at or after "Freeing unused memory"
> > >
> > > Thanks.
> > >
> > > excerpt from the page:
> > > (http://fedora.redhat.com/docs/udev/)
> > >
> > > Udev without initrd
> > >
> > > Install Fedore Core as usual and reboot. Execute the following commands
> > >
> > >
> > > mkdir /tmp/dev
> > > mount --move /dev /tmp/dev
> > > sbin/MAKEDEV null console zero
> > > mount --move /tmp/dev /dev
> > >
> > > Install your kernel without an initrd. Reboot.
> > >
> > > You will get some SELinux errors, and syslogd will not work as expected.
> >
> >
> > Why is it that you feel the need to rebuild the kernel?
> >
> > The centos/rhel system is built atop a very heavily patched kernel. If
> > you build from straight vanilla source from kernel.org, expect
> > breakage. There are things like selinux, nptl, etc that will break for
> > you, and may or may not cause apps to fail or behave erratically, the
> > system to hang (seems like you found that one already) etc.
> >
> > basically, if you need to rebuild the kernel, you should do so from
> > within the most recent kernel source rpm. Anything else is going to
> > cause issues, and you're likely to be on your own for help.
> >
> > All that negativity aside, there's a tutorial on how to rebuild
> > kernels via source rpm here:
> > crab-lab.zool.ohiou.edu/kevin/kernel-compilation-tutorial-en/
> >
> > Please. centos isn't gentoo and I'd advice not treating it as such if
> > it's possible. If what you need isn't in the stock kernel, then look
> > to the centosplus kernel. If it's not there, ask on the mailing list
> > or on irc. Others may need what you're after if you have a valid
> > reason.
> >
> >

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