booting from DVD image on hard drive partition

[stan]

On Thu, 22 Mar 2012 22:23:54 -0500 (CDT)
Michael Hennebry <hennebry at web.cs.ndsu.nodak.edu> wrote:

> On Thu, 22 Mar 2012, stan wrote:
> 

> > Perhaps Grub2 is using it somehow?  These suggestions are longshots.
> 
> grub2 is not installed on my machine.
> If it's packaged with the install kernel,
> then I would expecct them to be a matched set.

Then grub might be using it, and anaconda might not expect that from
the DVD.  As I said, this seems unlikely, but possible.

> >> I have noticed that all my kernels end in .PAE .
> >> Could that be significant?
> 
> Oops. I should have written .PAE.img

Kernels don't end in .img, that's the initrd / initramfs.  Here is a
sample kernel name:
vmlinuz-2.6.42.12-1.20120323.fc15.x86_64
Here is the rpm initramfs file name for that kernel:
initramfs-2.6.42.12-1.20120323.fc15.x86_64.img

> My machine is 32 bit.  Its cpu is a pentium 4.
> [hennebry at localhost ~]$ uname -a
> Linux localhost.localdomain 2.6.35.14-106.fc14.i686.PAE #1 SMP Wed
> Nov 23 13:39:51 UTC 2011 i686 i686 i386 GNU/Linux

I think pentium 4 is fairly old hardware.  I doubt either the kernel
developers or Fedora developers are using such hardware, and so you
could be hitting a regression that wasn't caught during
kernel development because no one is running that hardware.

> 
> >> > Another idea.  Maybe you can run dracut on the vmlinuz from the
> >> > DVD, and generate a custom (I think that is the -h option)
> >> > initramfs for your system.  Use it instead of the one from the
> >> > DVD when you boot from grub.
> >> 
> >> I've no idea how I would improve the initram already there.
> >> I don't even understand:
> >> dracut [OPTION]... <image>  <kernel-version>
> >> <image>?
> > initramfs
> 
> A sequence of bytes representing one partition
> containing the root file system?

From the man page, "dracut creates an initial image used by the kernel
for preloading the block device modules (such as IDE, SCSI or RAID)
which are needed to access the root filesystem."  In your case, this
will be the drivers for the hard drives you have.

> 
> >> <kernel-version>?
> > vmlinuz version
> 
> The name of a kernel?
No, the version of a kernel. In the kernel line from /boot
vmlinuz-2.6.42.12-1.20120323.fc15.x86_64
vmlinuz is the name, and the rest is the version.
> 
> > This is an example of the command I use to generate a custom
> > initramfs for my system.
> >
> > /sbin/dracut -f -H -v --debug
> > custom-2.6.42.10-1.20120315.fc15.x86_64.img
> > 2.6.42.10-1.20120315.fc15.x86_64 > dracut_output 2>&1
> > 
> > You should name the custom part whatever you want to call the
> > initramfs, and put the version of the vmlinuz in the second part.
> > It doesn't need the vmlinuz on the front.  If there are any errors,
> > they
> 
> What does the version do?

It tells it which kernel to create the initramfs for.

> 
> > will be in the dracut_output.  You could split the output so errors
> > go to their own file, > dracut_output 2> dracut_error, if you
> > want.  I've never tried this with a DVD image, so it might not work.
> 
> Are you suggesting that I make the DVD
> filesystem part of the initial ramdisk image?
> Wouldn't I also need whatever was in the prepackaged initial ramdisk
> image? How might the new ramdisk help me?

No.  I am suggesting you create a custom initramfs for the DVD kernel
for your system.  Use it instead of the generic DVD initramfs.  I am
suggesting this because it might allow the boot process to bypass the
problem it is having running the DVD kernel.  It should still find the
ISO image because of the kernel line parameters.  And you could be
right above.  I don't know if it requires the DVD ISO9660 fs or not in
the initramfs.  I think it should be able to get that from the kernel,
as it is probably compiled in or a module.  I don't know if this will
work, as this too is a long shot, but long shots seems to be all you
have left to try.