On 10/12/16 05:27 AM, Benjamin Herrenschmidt wrote: > On Fri, 2016-12-09 at 14:35 +0100, Daniel Vetter wrote: >>> As for multi userspace client, well, swapping an mmap between HW and >>> memory backing store is a somewhat solved problem already. >> >> Hm, I didn't know that, but then all existing drm drivers have fairly >> simplistic fbdev mmap implementations. > > Hrm, I though the TTM did it ... I remember talking with Thomas > Hellstrom about that back in the day... you use unmap_mapping_range > to unmap the existing mappings basically so you can take new faults > and route them to a different page, but I can't see a call in there > so maybe he ended up not doing it. I think he did, it was working fine for userspace mappings when I tried making radeon use a non-pinned BO for fbdev years ago (the problem was fbcon potentially trying to access the framebuffer at the most inconvenient times). There's still ttm_fbdev_mmap, but I'm not sure everything to make this fully work for userspace fbdev mappings is still there. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
