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 <fbar...@linux.vnet.ibm.com>
To: imun...@au1.ibm.com, michael.neul...@au1.ibm.com,
m...@ellerman.id.au, linuxppc-dev@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.
But it doesn't affect the API: the behavior of the API specifying the
number of interrupts for a context is consistent: the driver always
expects the number of AFU interrupts on bare-metal and in a LPAR. The
PSL interrupt is never included.
You can see a difference in the maximum number of attachable contexts
between bare-metal and powerVM (if the limiting factor is the number of
available interrupts). But there's no guarantee for that at the API level.
Fred
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