Fwd: [PATCH v4 08/18] cxl: IRQ allocation for guests

Manoj Kumar manoj at linux.vnet.ibm.com
Tue Feb 23 06:02:40 AEDT 2016


On 2/22/2016 8:46 AM, Frederic Barrat wrote:
> Le 21/02/2016 23:30, Manoj Kumar a écrit :
>>> Subject: [PATCH v4 08/18] cxl: IRQ allocation for guests
>>> Date: Tue, 16 Feb 2016 22:39:01 +0100
>>> From: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
>>> To: imunsie at au1.ibm.com, michael.neuling at au1.ibm.com,
>>> mpe at ellerman.id.au, linuxppc-dev at lists.ozlabs.org
>>>
>>> The PSL interrupt is not going to be multiplexed in a guest, so an
>>> interrupt will be allocated for it for each context.
>>
>> Not clear why this is the case. Why cannot the CXL later still
>> multiplex this in a guest? Is this a design choice, an
>> architectural issue, or the complexity of implementation did
>> not warrant this? From an API perspective it would have been
>> preferable to not cascade this change down to all consumers,
>> and have consumers aware whether they are working in a
>> bare-metal or a guest environment.
>
>
> It was a design choice made by pHyp. We cannot multiplex the PSL
> interrupt with the current pHyp implementation.

If that is the case, perhaps the commit message should be re-worded.
As currently written, it seems like it was a choice made by
this patch.

The PSL interrupt cannot be multiplexed in a guest, because blah...

--
Manoj Kumar



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