On 31 March 2011 21:23, Anthony Liguori <anth...@codemonkey.ws> 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
