Re: R/W HG memory mappings with kvm?

[Stephen Donnelly <sfdonnelly@gmail.com>]

On Thu, Jul 9, 2009 at 6:01 PM, Cam Macdonell<cam@cs.ualberta.ca> wrote:

>> Is there a corresponding qemu patch for the backend to the guest pci
>> driver?
>
> Oops right.   For some reason I can't my driver patch in patchwork.
>
> http://kerneltrap.org/mailarchive/linux-kvm/2009/5/7/5665734

Thanks for the link, I have read through the thread now. It seems very
relevant to what I am doing. Have you found a link to your qemu-kvm
backend patches? Or are you running your own git tree? I don't really
know where to look.

>> I'm curious how the buffer memory is allocated and how BAR
>> accesses are handled from the host side.
>
> The memory for the device allocated as a POSIX shared memory object and then
> mmapped on to the allocated BAR region in Qemu's allocated memory.  That's
> actually one spot that needs a bit of fixing by passing the already
> allocated memory object to qemu instead of mmapping on to it.

Right, I would be passing the memory in pre-allocated as well, but
should be a relatively simple change.

Regards,
Stephen.