Re: [Qemu-devel] [PATCH] Add Qemu A15 minimal support for ARM KVM

[bill4carson]

On 2011年10月24日 22:09, Peter Maydell wrote:
> On 29 September 2011 08:30,<address@hidden>  wrote:
> > From: Bill Carson<address@hidden>
> >
> > This patch add some A15 codes which enables ARM KVM could run
> > Guest OS build with Versatile Express Cortex-A15x4 tile.
> Thanks for sending this; I have somewhat belatedly written
> up some comments on it.
>
> I see the a15mpcore.c code is based on a version of mpcore.c
> which predates the MemoryRegion API changes -- we'll need to
> update it to use MemoryRegions.
OK, I will make it updated.
> There are some relics of 11MPCore peripherals lurking in there
> which need to be taken out. (I think we should probably clean
> up mpcore.c to separate out A9 from 11MPCore, incidentally.)
>
> The vexpress A9 and A15 init functions can probably share
> code although I haven't looked too closely there.
Neither did I :)
Anyway I will dig the code harder.

> For QEMU TCG we're going to want to model at least some
> of the cp15 registers (although probably mostly dummy
> implementations).
I'm not focusing on this by now, if this a MUST, I will try to do it.
> The A15 generic timer is accessed via cp15 registers rather
> than being memory mapped -- we need to decide which side of
> the KVM/QEMU boundary the model of that should live. (I'm
> guessing the right answer is "qemu side" which means we'll
> need an ABI between KVM and QEMU to pass (some) cp15 accesses
> through.)
right!

Current arch timer implementation will first check whether arch timer is 
implemented
*AND* whether arch timer frequency is set by security firmware.
If no arch timer available, SP804 will be used as clock source/event, 
that's what I am
using so far.

If generic timer need to be supported, this will fall into QEMU side, 
with the help of KVM
trapping any cp15 timer access. Anther issue is virtual timer support, I 
haven't make a
clear picture how virtual timer hardware fit into KVM smoothly, so let's 
focus on what
you proposed.

Anyway thanks for your suggestions, I will move on to next version to 
review :)


> thanks again
> -- PMM

--
I am a slow learner
but I will keep trying to fight for my dreams!

--bill