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

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 15.06.10 at 17:15, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
>> >>> Dom0 to map the IO-APIC space read-only? Perhaps even
> .. snip
>> Actually, that's a difference to non-pv-ops that I strongly
>> believe should be fixed: While in the traditional kernel
>> __direct_remap_pfn_range() is used to establish I/O memory
>> mappings (and hence there is a way to propagate errors), the
>> pv-ops kernel appears to use ioremap_page_range() - just like
>> native - which can only return -ENOMEM (upon page table
>> allocation failure), due to the lack of a return value from
>> set_pte_at().
>> 
>> But then again I must be missing something here, since
>> xen_set_pte_at() falls back to xen_set_pte() if the hypercall
>> it tries first fails, and that one would fault when establishing
>> the mapping, not when trying to first use it. Jeremy?
> 
> Take a look at xen_set_fixmap, which I think is used for most of those
> special addresses. It is mapped to a null-space for the IO APIC
> addresses.

I don't think that code matters here: execution goes through
acpi_os_map_memory(), and at the time the problem talked
about here happens I think the ioremap() in there ought to
be taken.

Jan


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