Re: [Xen-devel] [PATCH] xen/arm: Blacklist PMU with "arm, cortex-a53-pmu"

[Andre Przywara <andre.przywara@xxxxxxx>]

On Mon, 15 Apr 2019 13:41:41 +0530
Amit Tomer <amittomer25@xxxxxxxxx> wrote:

> Hello,
> 
> > After talking via IRC, the problem is PPIs, that this platform uses for
> > PMU interrupts. When Xen tries to setup the IRQ forwarding for Dom0 for
> > this device, it fails because it only supports forwarding SPIs.
> > So interestingly we erroneously forwarded A53 PMUs (those that are
> > described by that particular compatible string only) to Dom0 for quite a
> > while, but nobody noticed (or cared).
> >
> > Amit, please adjust the commit message accordingly.
> >  
> Ok but original commit "d45e9b7c53428a2aa4d067927e7ef5e30783fb8b" that 
> blacklist
> PMU's clearly states that issue is due to PPI and that can not be
> routed to guest.
> 
> I thought, This patch is just continuation of same.

Sure, but Julien was asking for a reason for this patch in the commit
message. There are quite some platforms which use this compatible string
already, and none of them failed so far. This is because they use SPIs,
but as the original commit message mentions there are more issues than just
the IRQs.

All this should be in the commit message. As you have seen yourself in Ian's
commit, it's quite helpful later on.

So you should mention:
a) the problem you encountered: PPI forwarding denied on iMX8
b) the reason for the problem: A53 PMU not blacklisted
c) the fix: adding the A53 compatible string to the blacklist

Cheers,
Andre.

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