Re: [Xen-devel] Debugging passthrough on an S3210SHLC

[Peter Kay <syllopsium@xxxxxxxxxxxxxxxx>]

On 19 March 2013 14:54, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Sat, Mar 16, 2013 at 04:05:19PM +0000, Peter Kay wrote:
>> On 15 March 2013 21:02, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
>> > On Fri, Mar 01, 2013 at 02:00:08PM +0000, Peter Kay wrote:
>> >> I'm having difficulty getting any passthrough working on an S3210SHLC 
>> >> (X38 derived S3210 socket 775 server chipset, thus pre SLAT) - this is on 
>> >> the list of supported hardware. Is there any guide as to what can be done 
>> >> - I've tried iommu=verbose, so is the next step sending debug printfs to 
>> >> the xen console? I realise this is a development list so I'd like advice 
>> >> on which bits of source to poke so I can find the root issue.
>> >>
>> >
>> > This hardware has actual IOMMU?
>> Yes, and I've passed hardware through in Esxi 5.1. It's a server
>> chipset with IOMMU, but pre Nehalem so the features are less complete.
>
> Oh. I didn't know that such mutants existed :-)
Yes - it's the original VT-d, as supported by the Q35, Q45, X38, X48
and S3200/S3210 chipsets (not on all motherboards). The Nehalem and
later supporting chipsets is termed by Intel as VT-d2 as it features
interrupt remapping, etc (except where it doesn't due to errata, as
per recent messages to the devel list).

>> Yes. I'm given to understand the passthrough parameter should maintain
>> the BDF - but it doesn't, and there appears to be no advice on this on
>> the Internet other than 'it should work' (but doesn't for some
>> people).
>
> That depends. The xen-pciback.vpci argument that define whether you
> want them to be virtual (so they start at 00) or match your host.
>
> But that option is only usefull for PV guests. I think you are using
> an HVM one. In which that does not matter that much I would think.
Yes, I'm using HVM. I'll have a look at vpci though, thanks!

Anyway, thank for the other recommendations - I've actually made a
fair bit of progress.

I swapped out the 3C900 for an 82557 (Pro 100) and everything started
working. Once I turned off video output completely and passed through
the embedded G200e (primary video on) I was also successfully able to
use X with it on a Wheezy HVM.

I've yet to get the 6950 working - it's seen, identified and bound to,
but then I get drm errors - there's no /dev/dri/card* devices. I'll
try swapping the fglrx driver for radeon and fiddling. Failing all
that I may try with the Fedora config that works for you. The one time
I got the 6950 to do something the fan ran at full pelt and hung the
whole machine, which really was a bit suboptimal.. Then again, I do
also have the relaxed option set for xen.

Thanks!

PK

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