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

Luke S Crawford lsc at prgmr.com
Fri Oct 31 23:57:14 UTC 2008

Kenneth Tanzer <ktanzer at desc.org> writes:

> It really honestly seems to me that sometimes I was getting
> inconsistent results, at least vis a vis the _current_ state of
> configuration files.  Also, I've had situations where I've been unable
> to destory machines from the graphical virt-manager, but able to do so
> with xm.  Yesterday, I had a guest that didn't show up on an xm list,
> but showed up in the virt-manager, constantly toggling between running
> and stopped.

xm and the virt-manager tools are different.  I would suggest either always
using one or always using the other.  

> My questions are:
> 1) whether either xm or virt-manager do any kind of caching of
> settings, so that your current configuration might not actually be
> what is executed?

libvirt (virt-manager) does use a different config file, and can convert from 
the xm config format (I don't know if it does this automatically or  if it
uses the xm config file unchanged or what.)  to the libvirt xml format.  
I would suggest you either use the libvirt/virt-manager tools, or the xm 
tools, but don't switch between them on the same installation, especially
for guest startup.  It's easy to get confused as to config file locations. 

if you want to use the libvirt tools on the command line, the tool you want
is virsh.

(personally, I use the xm tools, because I am more interested in Xen than
RedHat, though I am currently running Xen on CentOS.  I will, in fact,
be abandoning the redhat xen kernels on my next servers so I get PVGRUB. )

> 2) does going through the xen / grub boot process do any kind of
> changing or writing of settings?  Again, I swear there were times
> where I got different results on the second boot than the first one.

Pygrub is read-only, as far as I know.  It should not change your config
file or guest disk.

> 3) finally, what would account for the differences between
> virt-manager and xm, and also is there any magic way to destroy an
> un-destroyable machine without having to reboot your computer?

'xm destroy' has worked fine for me for some time.  I think it's been more than
a year since I've been unable to kill a zombie.    Are you running a recent

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