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Re: [Xen-devel] Powerdown problem on XEN | ACPI S5

that does not sound too promising at the moment. Is there anything else I could provide to come to a resolution given that I/O virtualization is what the system is supposed to do.

You mention ACPI tables - I have no clue how to provide those, but I am more than happy to do what I can?

Ian (Campbell) originally diverted me to Jan (Beulich) who seemed to have an idea before you thankfully jumped in. Jan's idea seemed to also revolve around ACPI - although not tables, but registers:

quote from Jan Beulich:
> It would be particularly interesting to know whether perhaps
> some of the ACPI registers live in memory space on that
> system - I already have a patch queued up (but not submitted
> yet) that fixes problems in that case.

@Jan: would it make sense to go down that route?

Thanks again to everybody for their help so far.

Am 14.08.13 22:38, schrieb Andrew Cooper:
On 14/08/13 21:24, Atom2 wrote:
Am 14.08.13 22:18, schrieb Andrew Cooper:

Ok thanks.

Do you mind confirming whether S5 works with "iommu=off" on the Xen
command line?


Yes, that works: The system powers off after issuing
     shutdown -h now
from the dom0.

So it is certainly an iommu interaction issue, which was sadly suspected
given that we have seen similar problems in the past.

Curiously, there are two IOMMUs on the system.  I am not familiar enough
with Cougar Point chipsets to know how they are layed out.  Perhaps the
ACPI tables might have more information.
I'm just curios, but where did you see two IOMMUs?

ACPI interaction with Xen is tricky at the best of times.  Xen as no AML
interpreter, so relies on Linux in dom0 to most of the ACPI legwork.

My best guess at the moment is that something in the ACPI code for S5 is
turning off enough of the PCH that Xen can no longer talk to the one of
the IOMMUs.


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