Re: [Xen-devel] [PATCH 5/5] xen: add new hypercall to get grant table limits

[Juergen Gross <jgross@xxxxxxxx>]

On 25/08/17 13:58, Jan Beulich wrote:
>>>> On 25.08.17 at 13:40, <jgross@xxxxxxxx> wrote:
>> So what about the following idea:
>>
>> - Set the default max number of grant frames to 32 on "small" hosts
>>   (max. physical memory address below 16TB) and to 64 on "large"
>>   hosts
> 
> This looks reasonable to me as long as it's properly documented.
> 
>> - Add a per-domain parameter for the max number of grant frames
>>
>> In the Linux kernel I would then:
>>
>> - Re-add grant v2 support
>> - Add boot parameter for selecting grant v1 or v2
>> - Use grant v2 if selected via boot parameter, or (pv only:) max. host
>>   address is above 16TB
> 
> Can a PV DomU know?

XENMEM_maximum_ram_page

> Plus can you easily switch between
> versions after having been migrated?

Other than console and xenbus there should be no active grant after
migration. So yes, I'm planning to support both, v1->v2 and v2->v1.

> And wouldn't HVM or ARM
> guests need to judge by max guest address?

Yes.


Juergen


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel