Re: [Xen-devel] Xen 4.0 crashes with pvops kernel

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 15.06.10 at 14:56, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
> On 15/06/2010 13:50, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> 
>> But even if we verify that the references come from some ACPI
>> method(s), likely the only way to address this is to fix the kernel
>> side error handling.
>> 
>> Keir, assuming these are reads only, would it make sense to permit
>> Dom0 to map the IO-APIC space read-only? Perhaps even
>> transparently converting writeable mappings to read-only ones
>> (since drivers/acpi/osl.c tries to establish writeable mappings
>> irrespective of the actual needs)? The obvious danger in doing
>> so is that going forward there may appear fields in that page
>> reads of which aren't side effect free...
> 
> Well, how come it works with other Linux kernels -- presumably they have
> some extra error handling in the ACPI subsystem? Shouldn't that just be
> added to this kernel?

I'm rather suspecting there's new code (compared to 2.6.18) that's
lacking proper error handling, though I didn't look in detail so far.

Hmm, looking a little more closely it seems they indeed try to write
to that space - this we for sure can't allow. I'll see if I can follow
the code path (unfortunately the stack trace is an imprecise one).

Cris, seeing DSDT and SSDTs from that system would surely be
helpful.

Jan


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