Re: [Qemu-devel] [PATCH 0/2] Remove CP15 timer from the device tree if KVM is used without in-kernel irqchip

[Peter Maydell]

On 25 June 2015 at 13:14, Pavel Fedin <address@hidden> wrote:
>> If we want to support "KVM but without in-kernel irqchip" I would
>> really prefer that we did it this way, by implementing an ABI for
>> letting the kernel tell us about the generic timer interrupts
>
>  Yes, but:
> 1. This would work only for newer kernels.
> 2. This little patch allows to work on older kernels, at least somehow.

I don't think "needs a newer kernel" is a particularly serious
restriction here.

Also some boards have no fallback timer device at all (notably
"virt", so generic-timer *has* to work.

>> IIRC chazy had a hacked-together patch for that at some point.
>
>  Who is it? Where can i find it?

I was misremembering. That's Christoffer Dall, and in fact he
didn't write any code, he just suggested that it was possible.

>> Is hardware with no working VGIC really prevalent enough that
>> it's worth adding support? Presumably the performance isn't going
>> to be very good...
>
>  At least RaspberryPi 2, as far as i know. Also i am testing on some
> Samsung proprietary HW which has the same problem.

I hope you have fed back to the h/w designers that they need
to fix this for the next revision :-)

thanks
-- PMM