Re: [Xen-users] Grub & kernel panics

[Martin Goldstone <m.j.goldstone@xxxxxxxxxxxxxxx>]

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The kernel included with Xen 3.1 is 2.6.18.  You may have trouble using
the sources for a different version in place of the included ones as the
files the Xen patches apply to may have changed, so the patches would
need fixing.  You should be able to boot with the version of 2.6.18 that
is shipped with the rest of Xen though, as long as you get your initrd
right.  What kernel are you trying to boot from at the moment?  The
kernel that shipped with FC6 (if so, which one?), or the kernel included
with the Xen tarball?

I've experienced panics at that point before as well.  I've used
noreboot at the end of the module line that has the dom0 kernel on to
stop the reboot.  Not sure about logging it to a file, obviously it
couldn't write to anywhere on the root file system (it can't find it),
so it'd have to be written to the boot file system, which I think is
mounted read-only, so I really don't know if it could be done.  You
could try capturing it over a serial line I suppose.

In the past, this panic's usually happened to me because I've not
included the correct modules in the initrd, or forgotten to do a depmod
on the xen kernel's modules.  The last time I had this problem was on an
LVM based CentOS 4.4 system, but as I rarely use an LVM based system, I
 haven't really tried to figure out where I went wrong, as I've not has
the time.  I do remember seeing messages about it not being able to find
any logical volumes, so I assume the LVM stuff was in there, must have
been missing something else.

I'd say your best bet is to try recreating your initrd for the xenified
kernel, and make sure you've got everything you need to boot in it. If
you've been trying to boot with Xen + a non-Xenified kernel, then it's
not going to work. You may be able to get away with FC6's kernel-xen
package (obviously built around Xen 3.0.3, so I don't know if it'll work
 brilliantly with Xen 3.1), personally I'd download the binary tarball
from the xen site and give the kernel in there a shot.  I'm using that
tarball on CentOS 5, and it's working fine.

HTH,

Martin

Rob van Oostveen wrote:
> Hi,
> 
> I may have simple question. I get a kernel panic during boot. After the panic
> an automatic reboot in 5 secs is initiated.
> 
> I tried using the panic=0 param in the grub kernel line, but that doesnt seem
> to work with the xen kernels. How can I make the system halt on panic? So I
> can read why it is panicing? Or better yet, how can make the boot process log
> to a file?
> 
> I installed redhat fc6 and than build Xen 3.1 from scratch with the kernel
> shipped with fc6. It panics with '/dev/root' cannot be found. 
> What kernel is Xen 3.1 based on? The kernel shipped with fc6 is 2.6.18-1. Can
> I use this kernel for building Xen 3.1?
> 
> Thanks in advance.
> 
> Regards,
> Rob
> 
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
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