Re: [PATCH 4/4 V3] irqchip: gicv2m: Add support for multiple MSI for ARM64 GICv2m

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On 8/1/2014 9:51 AM, Marc Zyngier wrote:
Hi Suravee,

On 01/08/14 15:36, Suravee Suthikulanit wrote:
On 7/30/2014 10:16 AM, Marc Zyngier wrote:
Why do we need this complexity at all? Is there any case where we'd want
to limit ourselves to a single vector for MSI?

I think the ARM64 GICv2m should not be the limitation for the devices
multiple MSI if there is no real hardware/design limitation.

arm64 is a new enough architecture so that we can expect all interrupt controllers to cope
with that.

I am not sure if I understand this comment.

We are not forcing all interrupt controllers for ARM64 to handle
multi-MSI.  They have the option to support if multi-MSI if they want
to. I just think that we should not put the architectural limit here.

Let me be clearer: I think we should put the burden of *not* handling
multi-MSI on interrupt controllers. Here, you're making the
architectural default to be "I don't support multi-MSI", hence having to
override global vectors and such for well behaved MSI controllers like
GICv2m and GICv3 ITS.

Let's only support multi-MSI for the time being. If someone comes up
with a silly old MSI controller that can't deal with it, we'll address
the issue at that problem.

Thanks,

	M.


Ok, I'm fine with that. Thanks for clarification.

Suravee

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