Re: PCI Pass-through in Xen ARM: Draft 4

[Julien Grall <julien.grall@citrix.com>]

On 14/08/15 15:37, Stefano Stabellini wrote:
> On Fri, 14 Aug 2015, Jan Beulich wrote:
>>>>> On 14.08.15 at 16:03, <stefano.stabellini@eu.citrix.com> wrote:
>>> On Fri, 14 Aug 2015, Jan Beulich wrote:
>>>>>>> On 14.08.15 at 15:21, <stefano.stabellini@eu.citrix.com> wrote:
>>>>> On Fri, 14 Aug 2015, Jan Beulich wrote:
>>>>>> it's even less clear how you'd expect to suppress this in other guest
>>>>>> OSes (Windows - afaik - being able to run on ARM certainly makes it
>>>>>> a candidate guest, even if maybe this doesn't work today), namely
>>>>>> such not having any pcifront. And I hope this design discussion isn't
>>>>>> limiting itself to Linux guests.
>>>>>
>>>>> We'll write down in the ABI documentation that BARs reassignments are
>>>>> not supported.
>>>>
>>>> I.e. guests doing so Will Not Work (TM), with users (usually not reading
>>>> ABI docs) learning it the hard way. Not nice, but a way to handle it.
>>>
>>> The target of the ABI docs is not users, but kernel developers, who
>>> should most definitely read them and fix their kernels.
>>
>> ??? (We're talking of unmodified, closed source OSes here.)
> 
> If you are thinking of Windows for ARM64, there isn't one yet.  When/if
> it will become available, there are going to be a number of issues to
> address before we can run it as a guest on Xen on ARM with the current
> architecture which doesn't do emulation. I am hopeful that we'll be able
> to have a discussion on ABI issues such as this one.

It may be worth to read [1] where the Xen ARM architecture is explained.

Regards,

[1]
http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions_whitepaper

-- 
Julien Grall