Re: [Xen-users] 2.6.18.8 xen.org dom0 kernel w/RHEL 5 PV on HVM guests

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Mar 18, 2010 at 03:20:45PM -0700, Andrew Evans wrote:
> >>
> >> (XEN) event_channel.c:192:d0 EVTCHNOP failure: domain 13, error -22
> >> (XEN) event_channel.c:192:d0 EVTCHNOP failure: domain 13, error -22
> >> (XEN) event_channel.c:192:d0 EVTCHNOP failure: domain 13, error -22
> >>
> >>     
> > These sound related..
> >   
> 
> Yup. I can't believe event channels are generally broken though, as the
> PV network driver works and the PV disk driver works once the system
> comes up.
>

Ok. I wonder if there's some timeout related change in the RHEL5 dom0 kernel,
and the RHEL5 pv-on-hvm drivers depends on it? 
 
> >> If I boot this same VM without disabling the IDE drivers, it mounts
> >> filesystems using /dev/hd* and starts up successfully. Now here's the
> >> baffling part: I can then mount / and /home using /dev/xvd*! So the
> >> paravirt disk driver *is* working once the domU boots off /dev/hd*, but
> >> for some reason it doesn't work when I try to boot from /dev/xvd* directly.
> >>
> >> So my questions are:
> >>
> >> 1. Why can't the initrd mount /dev/xvd* to / ?
> >>
> >>     
> > Because the devices don't work for some reason..
> >   
> 
> Well, yeah, I had worked that much out on my own. :) I can't imagine
> what miracle is occurring between the time that initrd/nash tries to
> mount /dev/xvda3 to / and when I do it manually from the command line
> once I'm able to to log in, but such a miracle is in fact occurring!
> 

Maybe it's just some timeout.. 

> >> 2. Why does this work with the RHEL 5 dom0 kernel but not with a
> >> similarly-configured xen-unstable 2.6.18.8 dom0 kernel?
> >>
> >>     
> > That's a good question.
> >
> >   
> >> xen-unstable 2.6.18.8 dom0 kernel config attached. I've gotten the
> >> Xen-related stuff as close to RHEL 5 as I can, but available CONFIG_*
> >> defines vary somewhat between the two kernel source trees.
> >>
> >> Thanks for any help anyone can provide.
> >>
> >>     
> > So the dom0 kernel was the only thing you changed?
> >   
> 
> Yes.
> 
> > You used the same Xen hypervisor for both dom0 kernels? which hypervisor 
> > version? 
> >   
> 
> Xen 3.4.2, rebuilt from gitco source RPM w/oprofile active domains patch
> applied:
> 

Hmm.. can you try with the RHEL5 default hypervisor (3.1.2) ? 
(and the 2.6.18-xen dom0 kernel) 

Would be good to know if it makes any difference.

-- Pasi


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