[CentOS-virt] Can't get PCI card visible in guest

Todd Deshane deshantm at gmail.com
Fri Oct 31 00:15:38 UTC 2008

On Thu, Oct 30, 2008 at 8:04 PM, Kenneth Tanzer <ktanzer at desc.org> wrote:
>> I am not seeing the errors in the red hat based boot that I am familiar
>> with,
> As I understand it, this Asterisk disk I have is built on Centos 5.2, so I'm
> assuming Asterisk=CentOS=Redhat, at least for this purpose.

Yeah, I meant Red Hat-based, CentOS, fedora etc. are quite similar

>> it seems that you are running into one of the following (or
>> similar:
>> Your guest root file system is not where you expect it to be.
>> If you haven't already, check the grub.conf in the guest.
> Here's my grub file:
> title CentOS (2.6.18-92.1.13.el5xen)
>       root (hd0,0)
>       kernel /xen.gz-2.6.18-92.1.13.el5
>       module /vmlinuz-2.6.18-92.1.13.el5xen ro root=/dev/VolGroup00/LogVol00
>       module /initrd-2.6.18-92.1.13.el5xen.img
> Here's the corresponding xen entries:
> kernel="/boot/vmlinuz-2.6.18-92.1.13.el5xen"
> ramdisk="/boot/initrd-2.6.18-92.1.13.el5xen.img"
> root="/dev/VolGroup00/LogVol00"
> extra="ro"
> They seem to match to me.  Sanity check:  the "root" in the xen config is
> specified as seen by the guest, right?

Yes, with the guest disk image.

>> OR
>> You are missing modules in your ramdisk that are needed by your guest
>> (in which case you would need to use mkinitrd to rebuild your xen initrd
>> and make sure you include the necessary modules)
> I can boot the xen kernel as a fully-virtualized machine (with the grub.conf
> mentioned above).  Is that a fair indicator that all the required modules
> exist?  If not, any idea how to figure out what might be missing?

Actually no, the fully virtual kernel modules in the guest are not used
when booting with the kernel and ramdisk options in the xen config.

Some of those more familiar with centos might be able to jump in
to help with specific modules, but if I was you I would boot the
full virtual guest, do an lsmod and compare the modules, especially
the ones to do with disk drivers, lvm, device mappers etc. with the
/lib/modules/<xen kernel version>/modules

Simply rebuilding the initrd with a mkinitrd and the right modules
included might be all you need. This only the basic idea, I would
suggest to take some time to search xen.markmail.org for either
error messags or key words that may lead you to some exact
instructions of the mkinitrd that will work for your setup.

Hope that helps,

Todd Deshane

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