Re: [Xen-devel] [TestDay] Xen crash on boot

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.01.14 at 06:40, Eric Houby <ehouby@xxxxxxxxx> wrote:
> Adding acpi_skip_timer_override to the xen command line did allow Dom0
> to boot but the video display for Dom0 did not work.  The following log
> was still seen the logs.
> 
> (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 0, device id = 0xa0, fault address
> = 0xfdf8020140, flags = 0x8

Okay - we clearly need to understand where these faults in the
HT range come from. I'm adding Suravee for that reason.

> Including iommu=no-amd-iommu-perdev-intremap along with
> acpi_skip_timer_override cleared the above errors and Dom0 video was
> functional.  Attempts to passthrough a secondary VGA to a Win8.1 guest
> was not successful with these logs in the xen console:
> 
> (XEN) AMD-Vi: IO_PAGE_FAULT: domain = 1, device id = 0x700, fault
> address = 0x11620df40, flags = 0

I don't think we care about any such advanced functionality right
now.

> Attached are two xen console boot logs, one with just
> acpi_skip_timer_override in the xen command line and the other with
> acpi_skip_timer_override and iommu=no-amd-iommu-perdev-intremap.  The
> long files names I used make it clear which is which.

That's not really better:

(XEN) ..TIMER: vector=0xF0 apic1=0 pin1=0 apic2=-1 pin2=-1
(XEN) ..MP-BIOS bug: 8254 timer not connected to IO-APIC
(XEN) ...trying to set up timer (IRQ0) through the 8259A ...  failed.
(XEN) ...trying to set up timer as Virtual Wire IRQ... works.

We specifically want to avoid all of these workarounds.

> I tried to see how a native kernel handled the timer bug you mentioned
> but I could not find a corresponding log when booting 3.12.7 on bare
> hardware. This boot log is attached as barehw.txt, maybe there is
> something you can find.

But you didn't turn on interrupt remapping, or it got forcibly
disabled:

[Firmware Bug]: AMD-Vi: No southbridge IOAPIC found
AMD-Vi: Disabling interrupt remapping

so the comparison isn't really between equal configurations. If
the kernel responds to that mentioned firmware bug by forcing
interrupt remapping off, maybe we would have to do the same...

Jan


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