On Thu, Jan 19, 2012 at 10:59:01AM -0800, Matt Thomas wrote:
>
> For prefetchable regions (like framebuffers) mapped by bus_space_map, there
> is a need to able force the contents out of the cache back into memory
> (especially when the cache is a writeback cache).
>
> There is no MI way to do this with the bus_space framework so I'm proposing
> we add a:
>
> void bus_space_sync(bus_space_tag_t bst,
> bus_space_handle_t bsh,
> bus_size_t offset,
> bus_size_t length,
> int ops);
>
> where ops is one of:
>
> #define BUS_SPACE_SYNC_WB 1 // defined by MD
> #define BUS_SPACE_SYNC_WBINV 2 // defined by MD
>
> One caveat is that though a BUS_SPACE_SYNC_WB was requested, a platform can
> perform BUS_SPACE_SYNC_WBINV instead. If the platform can't support just
> writeback, it is allowed to silently do a writeback-invalidate instead.
Isn't this what bus_space_barrier(BUS_SPACE_BARRIER_SYNC) is for ?
--
Manuel Bouyer <bou...@antioche.eu.org>
NetBSD: 26 ans d'experience feront toujours la difference
--
