[Mesa-dev] [PATCH 4/5] r600g, radeonsi: Use write-combined persistent GTT mappings

Marek Olšák maraeo at gmail.com
Fri Jul 18 04:45:36 PDT 2014

If the requirements of GL_MAP_COHERENT_BIT are satisfied, then the
patch is okay.


On Fri, Jul 18, 2014 at 5:19 AM, Michel Dänzer <michel at daenzer.net> wrote:
> On 17.07.2014 21:00, Marek Olšák wrote:
>> On Thu, Jul 17, 2014 at 12:01 PM, Michel Dänzer <michel at daenzer.net> wrote:
>>> From: Michel Dänzer <michel.daenzer at amd.com>
>>> This is hopefully safe: The kernel makes sure writes to these mappings
>>> finish before the GPU might start reading from them, and the GPU caches
>>> are invalidated at the start of a command stream.
>> The resource flags actually tell you what you can do. If the COHERENT
>> flag is set, the mapping must be cached.
> Why is that required? As I explain above, we should satisfy the
> requirements of the ARB_buffer_storage extension AFAICT.
> As pointed out by you and Grigori in other posts, I should probably just
> drop the special treatment of persistent mappings though, so the
> placement and flags are derived from the buffer usage.
> --
> Earthling Michel Dänzer            |                  http://www.amd.com
> Libre software enthusiast          |                Mesa and X developer

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