Re: [Qemu-devel] [PATCH RFC] vga: flag vga ram for notifiers

[Peter Maydell]

On 31 March 2011 21:23, Anthony Liguori <address@hidden> wrote:
> On 03/31/2011 03:12 PM, Peter Maydell wrote:
>> Well, obviously you need to be able to revoke the permission
>> to use the fastpath pointer to the underlying memory. But you
>> need to be able to do that anyhow, to cover cases where (eg) the
>> guest has just written to some register that remaps the bottom
>> part of the address space so it's ROM rather than RAM, or whatever.
>> It's just a feature your optimisation needs to have. Equally, you
>> don't remap unless you have to, but if the mapping's changed then
>> it's changed...
>
> Right, the trouble now is that there's no way to distinguish between mapping
> where 1) we don't care about them in virtio and 2) they change frequently.

Aha. Thanks for the explanation.

> Maybe the right approach here is to just use a virtio specific API and
> register RAM as register_virtio_dma_area().

That seems like a clearer API, yes. I think it makes it much more
obvious what it's trying to achieve.

-- PMM