Re: [PATCH] stubdom: foreignmemory: Fix build after 0dbb4be739c5

[Juergen Gross <jgross@suse.com>]

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On 13.07.21 16:38, Julien Grall wrote:
> Hi Juergen,
> 
> On 13/07/2021 15:23, Juergen Gross wrote:
>> On 13.07.21 16:19, Julien Grall wrote:
>>> Hi Jan,
>>>
>>> On 13/07/2021 15:14, Jan Beulich wrote:
>>>>> And I don't think it should be named XC_PAGE_*, but rather XEN_PAGE_*.
>>>>
>>>> Even that doesn't seem right to me, at least in principle. There 
>>>> shouldn't
>>>> be a build time setting when it may vary at runtime. IOW on Arm I 
>>>> think a
>>>> runtime query to the hypervisor would be needed instead.
>>>
>>> Yes, we want to be able to use the same userspace/OS without 
>>> rebuilding to a specific hypervisor page size.
>>
>> This define is used for accessing data of other domains. See the define
>> for XEN_PAGE_SIZE in xen/include/public/io/ring.h
>>
>> So it should be a constant (minimal) page size for all hypervisors and
>> guests of an architecture.
> 
> Do you mean the maximum rather than minimal? If you use the minimal 
> (4KB), then you would not be able to map the page in the stage-2 if the 
> hypervisor is using 64KB.

But this would mean that the current solution to use XC_PAGE_SIZE is
wrong, as this is 4k.


Juergen


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