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Re: [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- Date: Wed, 22 Mar 2023 07:32:06 +0000
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- Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 22 Mar 2023 07:32:35 +0000
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- Thread-topic: [PATCH v3 06/10] xen/arm: enable Dom0 to use SVE feature
> On 20 Mar 2023, at 09:13, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 17.03.2023 14:19, Luca Fancellu wrote:
>> --- a/docs/misc/xen-command-line.pandoc
>> +++ b/docs/misc/xen-command-line.pandoc
>> @@ -1005,6 +1005,19 @@ restrictions set up here. Note that the values to be
>> specified here are
>> ACPI PXM ones, not Xen internal node numbers. `relaxed` sets up vCPU
>> affinities to prefer but be not limited to the specified node(s).
>>
>> +### dom0_sve (arm)
>> +> `= <integer>`
>> +
>> +> Default: `0`
>> +
>> +Enable arm SVE usage for Dom0 domain and sets the maximum SVE vector length.
>> +Values above 0 means feature is enabled for Dom0, otherwise feature is
>> disabled.
>> +Possible values are from 0 to maximum 2048, being multiple of 128, that
>> will be
>> +the maximum vector length.
>> +Please note that the platform can supports a lower value, if the requested
>> value
>> +is above the supported one, the domain creation will fail and the system
>> will
>> +stop.
>> +
>> ### dom0_vcpus_pin
>>> `= <boolean>`
>
> I'd like to raise the question of proliferation of top-level command
> line options controlling Dom0. In x86 we've specifically started to use
> "dom0=" as the one top-level option where almost all new controls should
> be added as sub-options.
>
> _If_ a top-level option is indeed preferred, then please avoid the use
> of an underscore in its name, when a dash does fine.
Yes, maybe something like dom0=sve=<VL>,[...] is nice for new possible incoming
features,
While I was browsing the code, I spotted a possible bug in x86/dom0_build.c, in
parse_dom0_param(...) if an option is not recognised we set rc = -EINVAL, but
we don’t
stop the loop and we continue to parse.
Is it the intended behaviour?
>
> Jan
|
