Re: RE: [Xen-users] (Xenlinux) gentoo-xen-kernel patches questions?

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 04/02/2010 11:03 AM, Mike Viau wrote:
> >>Hi,
> >>
> >>I noticed that the Xenlinux 2.6.33 patches are tagged as being 
> "Deprecated" but the 2.6.31 are not.
> >>
> >>May I ask why?
> >>
> >>http://code.google.com/p/gentoo-xen-kernel/downloads/list?can=1&q=&colspec=Filename+Summary+Uploaded+Size+DownloadCount 
> <http://code.google.com/p/gentoo-xen-kernel/downloads/list?can=1&q=&colspec=Filename+Summary+Uploaded+Size+DownloadCount>
> >>
> >>
> > Fri, 2 Apr 2010 13:15:09 -0400 <konrad.wilk@oracle.com> wrote:
> >
> > No idea. But those patches are pursuing an entirely different method of
> > getting Linux to work in privileged state (Dom0). The current
> > development is with the pv-ops one:
> >
> > http://wiki.xensource.com/xenwiki/XenParavirtOps
> >
>
> I am currently using the unstable version of debain's pvops xen kernel.
>
> http://packages.debian.org/sid/linux-image-2.6.32-4-xen-amd64
>
> It appears to have functioning networking and block devices which is 
> nice, but I have experienced some instabilities such as kernel dumping 
> on reboots. Unfortunately I do not have a console setup to log kernel 
> messages for this machine.

That would be interesting to see.  I have also seen oops messages on 
reboot, if you reboot while domains are still running.  For me, at 
least, it appears to be a bug in blktap2.  It would be useful if you 
could confirm that's what your crashes are, or if its something else.

> Would compiling the pv_ops kernel from the git repository produce any 
> additional stability?

I'm not really sure what the Debian image is built from, so its hard to 
say.  I'm getting the impression that their build is pretty closely 
tracking xen.git now.  Are you seeing any other stability problems?  
Because, honestly, a crash while rebooting is annoying and should be 
fixed, it doesn't really count as a stability problem if you're 
rebooting anyway ;).  (Unless it either prevents the reboot from 
working, or causes data-corruption on disk.)

> It was my understanding that one could run a stable Xen systems today 
> with a Xenlinux kernel, as pv_ops was still in development. I've read 
> on the XenParavirtsOps page that there are features available to Xen 
> but are not yet available in the pv_ops kernel (perhaps this wiki has 
> not been updated as I understand Xen 4.0 release is just around the 
> corner!):

I'm pretty sure the Debian kernel is pvops based, so any caveats or 
limitations of one apply to the other.

     J