On Wed, Jul 31, 2019 at 11:40 PM Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote: > > On Wed, Jul 31, 2019 at 07:25:13PM -0700, Gurchetan Singh wrote: > > The main use for udmabuf is sending guest memory pages > > to the host. > > > > It's generally a bad idea to have to separate mappings with > > different attributes. For example, a WC mapping the guest > > kernel and cached mapping on the host is problematic. > > > > Add creation time flags so the user has responsibility for > > the specific use case. > > > -#define UDMABUF_FLAGS_CLOEXEC 0x01 > > +#define UDMABUF_FLAGS_CLOEXEC 0x01 > > +#define UDMABUF_FLAGS_PROT_NONE 0x02 > > +#define UDMABUF_FLAGS_PROT_READ 0x04 > > +#define UDMABUF_FLAGS_PROT_WRITE 0x08 > > [ didn't look at followup patches yet ] > > You can't have readonly/writeonly dmabufs. > So that isn't going to fly. > > The commit message suggests this is for cache attributes not protection, > so having the flags might make sense, but please don't name the flags > PROT_* then. Okay, I'll change the flags to CACHED / UNCACHED / WRITE_COMBINE (like msm_drm.h). And since the dma api doesn't work on x86 [1], we'll have to call drm_cflush_pages in the guest. Since caching is privileged on ARM and not on x86, that *should* get us write-combine guest buffers. [1] https://lists.freedesktop.org/archives/dri-devel/2019-August/229161.html > > cheers, > Gerd > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
