Re: [Xen-users] pci passthrough with multiple devices

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Aug 14, 2012 at 11:27:45AM +0100, Ian Campbell wrote:
> On Fri, 2012-08-10 at 18:03 +0100, Gabor Hudiczius wrote:
> > > thanks, it works perfectly with the latest 4.2 (4.2.0-rc2-pre)
> > 
> > Hi,
> > 
> > well, it's not quite perfect...
> > 
> > When i try to set a maxmem value different from the memory value, the 
> > guest doesn't start
> 
> I think this is probably/likely a kernel issue (so I've CC'd Konrad)
> Setting "host_e820=1" in the guest cfg might help, but I've a feeling it

It is called 'e820_host=1'

> happens automagically if you specify "pci = " so perhaps not.

No. You still need to provide e820_host=1 and pci=xxx stanze for
that to work.
> 
> You might need swiotlb=force too, Konrad can probably best advise.

iommu=soft.
> 
> I'd be useful to see the actual kernel logs from both the success and
> failure case. I set "XENCONSOLED_TRACE=guest"
> in /etc/{sysconfig,default}/xencommon (which one you have depends on
> distro) and mkdir /var/log/xen/console, after restarting xenconsoled you
> should get a log file for each guest.
> 
> 
> > Other guests work fine, and this one starts too, when i delete either 
> > the pci or the maxmem settings, or when i set the maxmem value equal to 
> > the memory value.

I have to confess that I don't recall testing maxmem/memory without
e820_host option as well, the e820_host=1 is the option to make it
work. Without the e820_host the E820 that is put in the guest
is not very PCI friendly and you are probably populating the memory
that the PCI card is using.

> > 
> > I attach the guest config (rita), the xl log (xl-rita.log), and the 
> > output of both a successful (rita-start-success) and a failed 
> > (rita-start-failure) create attempt (xl -vvv create rita).
> > 
> > Both xm create and xm mem-set works.

I should mention that 'e820_host' option is only available in 'xl'.
I did write a patch for xm (see attached) but since xend is deprecated
did not think to post it.
> > 
> > Regards,
> > Gabor Hudiczius
>

Attachment: xend-use-domain_set_e820_hole.patch
Description: Text document

Attachment: xend-xc-lowlevel-stub.patch
Description: Text document

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