Re: RFC: New bus_space routine: bus_space_sync

[Matt Thomas <matt%3am-software.com@localhost>]

On Jan 21, 2012, at 3:06 AM, David Laight wrote:

> 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).
> 
> Don't some ethernet drivers already have to do this - for systems
> where the cpu's cache isn't snooped by the dma accesses.

That's a different API (bus_dmamap_sync).

> There is subtle difference as to whether would need an 'invalidate'
> the cache line (with or without a writeback).

Which is why i left invalidate out.  Some x86 don't have it.