Re: [Xen-devel] Xen-unstable: pci-passthrough of device using MSI-X interrupts not working after commit x86/MSI: track host and guest masking separately

[linux@xxxxxxxxxxxxxx]

On 2015-06-26 17:04, Jan Beulich wrote:
> (re-adding xen-devel)
Sorry mist the reply-all button.

> > > > On 26.06.15 at 15:38, <linux@xxxxxxxxxxxxxx> wrote:
> > On 2015-06-26 14:41, Jan Beulich wrote:
> > > > > > On 26.06.15 at 13:02, <linux@xxxxxxxxxxxxxx> wrote:
> > > > Strange, i don't see *any* of your printk's being hit ... (xl dmesg
> > > > attached).
> > > So does the guest (in the working case) use MSI-X at all for the
> > > device? I.e. it might be worth comparing the guest's /proc/interrupts
> > > from both cases, as the lack of any of the debug messages clearly
> > > suggests that such interrupts aren#t being set up.
> > In the good case it uses one of them.
> > (probably one per port and it has only one usb device connected at
> > present)
> >
> > --
> > Sander
> >
> >           CPU0       CPU1       CPU2       CPU3
> >    0:         42          0          0          0   IO-APIC   2-edge   
> >    timer
> > [...]
> >   83:          8          0          0          0   xen-dyn-event     
> > eth0-q3-rx
> >   84:       2101          0          0          0  xen-pirq-msi-x    
> > xhci_hcd
> I think this explains it - you're running in PVHVM mode, which I
> never tried with those patches. I'd even have to go dig to see how
> they drive MSI-X in the first place in that case. Nor do I immediately
> know whether there's an option to make a guest become a normal
> HVM one again.
>
> Jan
Hmm i had to read up on the difference ..
http://wiki.xen.org/wiki/Virtualization_Spectrum#Paravirtualizing_little_by_little:_PVHVM_mode

But doesn't it almost always do that on linux guests (since most kernels 
will have need Xen stuff enabled) ?
--
Sander




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