Re: [Xen-devel] [PATCH v4 18/22] xen/pci: Pay attention to PCI_MSIX_TABLE_OFFSET

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.04.13 at 18:42, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> On Thu, Apr 25, 2013 at 10:40:57AM +0100, Jan Beulich wrote:
>> Recent hypervisors will actually
>> only consume this to issue a warning if not matching what gets
>> read from the corresponding BAR. Earlier hypervisors used this
>> instead of reading the BAR.
> 
> Note that pci_resource_start() gives you a CPU address, and what you
> read from the BAR is a PCI bus address.  These are not in the same
> address space and can't be directly compared.  I assume the
> hypervisors take that into account and do the appropriate
> conversions?

I suppose Xen has never been run on a system where the two
would differ, and it's quite likely that it would break on such
systems. Question is - are there any x86-based systems where
this is the case?

Jan


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