RE: [Xen-users] 3.4-testing : Kernel panic on bootup (mount: couldnotfind filesystem /dev/root/)

["Madhu Venugopal (vmadhu)" <vmadhu@xxxxxxxxx>]

> >
> > Okay. How would I find what modules are missing ?
> > I don't see any such error in the bootup logs. Any other suggestions
> ?
> 
> Start with the boot log. It usually shows you what block devices are
> detected, etc.
> The basic ones for domU (2.6.18 kernel) are xenblk (domU block device)
> and ext3 (or whatever file system you use). For dom0 kernel, it's
> easier to see the output of "lsmod" from your working installation.

I tried lsmod on the Base CentOS 5.3 installation and saw these :

<lsmod>
dm_raid45              66509  0 
dm_message              6977  1 dm_raid45
dm_region_hash         15681  1 dm_raid45
dm_log                 14529  3 dm_mirror,dm_raid45,dm_region_hash
dm_mod                 62201  4 dm_mirror,dm_multipath,dm_raid45,dm_log
dm_mem_cache            9537  1 dm_raid45
ata_piix               23621  0 
libata                156933  1 ata_piix
cciss                  63813  3 
sd_mod                 25153  0 
scsi_mod              141589  6 scsi_dh,sr_mod,sg,libata,cciss,sd_mod
ext3                  124233  1 
jbd                    56937  1 ext3
<lsmod>

I could not see the dm_raid45, dm_region_hash in the
/lib/modules/2.6.18.8-xen/kernel
Directory. Hence I copied these from /lib/modules/2.6.18-128.el5PAE/.

After this I ran mkinitrd again. I still see the kernel panic, Also I
see a few error
message during bootup : "dm-raid45: disagrees about version of
symbol..."...

Looks like I cant just copy over the modules...

I will try your other suggestions...

-Madhu

> 
> >
> >>
> >> - Install RHEL's Xen. This should be pretty straightforward, you'd
> end
> >> up with Xen 3.1+ and a working grub.conf stanza for Xen with RHEL's
> >> kernel-xen
> >> - Install Xen package from gitco (http://www.gitco.de/repo/). You
> can
> >> get Xen 3.4.1 (currently in testing) but still using RHEL's kernel-
> xen
> >> - If that works, you can simply compile another xen kernel as you
> >> like, using either 2.6.18 or later pv_ops kernel. If using 2.6.18,
> you
> >> can use RHEL's kernel-xen config as a base.
> >
> > I didn't want to take this approach. We have standardized on the
> > approach
> > to take with the existing XEN installations and kernel to use.
> 
> Standard is fine, if it works. What I'm saying is if you want to find
> out what's wrong (is it Xen userland? kernel version? kernel config?)
> the steps above can help.
> 
> > It is
> > confusing
> > that am the only one seeing this issue while it works just fine on
> other
> > Machines. This makes it clear that it is machine specific and am
> missing
> > Some drivers for them. But am clueless on what is that am missing
and
> > how
> > To include them in initrd. Any suggestions ?
> 
> For starters, copy RHEL's kernel-xen config to the kernel from xen.org
> (like
http://bits.xensource.com/oss-xen/release/3.4.0/linux-2.6.18-xen-
> 3.4.0.tar.gz).
> That should provide similar set of modules.
> 
> Then try running mkinitrd WITHOUT --allow-missing. It should show you
> what modules it thinks you should have but currently missing.
> 
> --
> Fajar

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