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Re: [PATCH v5 00/12] SVE feature for arm guests
- To: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
- From: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- Date: Tue, 18 Apr 2023 14:41:07 +0000
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- Cc: Julien Grall <julien@xxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Nick Rosbrook <rosbrookn@xxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Christian Lindig <christian.lindig@xxxxxxxxxx>, David Scott <dave@xxxxxxxxxx>, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>, Henry Wang <Henry.Wang@xxxxxxx>, Community Manager <community.manager@xxxxxxxxxxxxxx>
- Delivery-date: Tue, 18 Apr 2023 14:41:30 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH v5 00/12] SVE feature for arm guests
> On 18 Apr 2023, at 15:38, Bertrand Marquis <Bertrand.Marquis@xxxxxxx> wrote:
>
> Hi Julien,
>
>> On 18 Apr 2023, at 16:25, Julien Grall <julien@xxxxxxx> wrote:
>>
>>
>>
>> On 18/04/2023 14:13, Bertrand Marquis wrote:
>>> Hi Luca,
>>
>> Hi,
>>
>>> On this serie I would like to open a discussion on how to handle the vector
>>> size
>>> and the corresponding command line / configuration / device tree parameters.
>>> In general the user must either give a vector size it wants or has a
>>> solution to
>>> just request the maximum supported size.
>>> In the current implementation if a size bigger than the supported one is
>>> provided:
>>> - we silently disable SVE for dom0
>>> - we silently disable SVE for dom0less
>>> - we do not create a guest when done through tools
>>> This is not completely coherent and i think we should aim for a coherent
>>> behaviour
>>> unless we have arguments for this status.
>>
>> +1.
>>
>>> Is there any good reason to silently disable for Dom0 and dom0less only ?
>>> I see some possible solutions here:
>>> - modify parameter behaviour to use the supported size if parameter is
>>> bigger than
>>> it. This would at least keep SVE enabled if a VM depends on it and could
>>> simplify
>>> some of the handling by using 2048 to use the maximum supported size.
>>
>> My concern with this approach and the third one is the user may take some
>> time to realize the problem in the xl.cfg. So...
>
> Good point
>
>>
>>> - coherently stop if the parameter value is not supported (including if sve
>>> is
>>> not supported)
>>
>> ... this is my preferred approach because it would be clear that the value
>> passed to Xen is bogus.
>
> I agree: we should not silently ignore configuration parameters or try to
> "fix" them.
Hi Bertrand and Julien,
Ok I will update the serie to stop the domain creation if the parameter
supplied is wrong or SVE is not supported by the platform.
>
> Cheers
> Bertrand
|
