Re: [Qemu-devel] [RFC ppc-next PATCH 3/6] memory: add memory_region_to_address()

[Alexander Graf]

On 21.03.2013, at 12:01, Peter Maydell wrote:

> On 21 March 2013 10:59, Alexander Graf <address@hidden> wrote:
>> On 21.03.2013, at 11:53, Peter Maydell wrote:
>>> Check kvm_arm_register_device() in target-arm/kvm.c. Basically
>>> the VGIC device model calls this function to say "tell the kernel
>>> where this MemoryRegion is in the system address space, when it
>>> eventually gets mapped". The code in kvm.c uses the memory system's
>>> Notifier API to get a callback when the region is mapped into
>>> an address space, which it uses to track the offset in the
>>> address space. Finally, we use a machine init notifier so that
>>> just before everything finally starts we can make the KVM ioctls
>>> to say "here is where everything lives".
>> 
>> Same thing here. The question is how the kvm-vgic code in QEMU
>> finds out where it got mapped to. Scott adds this patch to do
>> this, but I'd assume you have some other way :)
> 
> Hmm? The kvm-vgic code in QEMU doesn't need to know where it
> lives. We have to tell the kernel so it can map its bits of
> registers in at the right place, that's all.

The kvm-vgic code in QEMU needs to tell the kernel, no? For that, it needs to 
know what to tell the kernel.

This patch adds a function that allows kvm-openpic to fetch its base flat 
address from the MemoryListener. I was wondering whether either this patch is 
superfluous or you guys had an awkward MemoryListener handler :)


Alex