Re: [Xen-devel] [PATCH v2 14/15] xen/arm: vgic: Drop iactive, ipend, pendsgi field

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 02/02/15 16:05, Ian Campbell wrote:
> On Thu, 2015-01-29 at 18:25 +0000, Julien Grall wrote:
>> The current VGIC code doesn't support to change the pending and active status
>> of an IRQ via the (re-)distributor.
>> If we plan to support it in the future, it will unlikely require a specific
>> bitfield as we already store the status per vIRQ.
> 
> I think we would want to track the state like we do for enabled, since
> walking 32 virqs to construct the value would be a bit expensive.
> 
> Stefano, what do you think?

The current code is actually buggy, when not doing nothing.

Hiding the fact that those bits are supported is the worst things to do.
The kernel developer may spend hours, if not days, before finding that
we just ignore the write in those registers.

As it's not supported, and may require some works, it better to drop it
than silently ignore failure (in case of vGICv3).

Regards,

-- 
Julien Grall

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