On Thu Feb 5, 2026 at 2:16 AM CET, Dave Airlie wrote: > On Fri, 28 Mar 2025 at 21:09, Danilo Krummrich <[email protected]> wrote: >> >> (CC: Ben, John) >> >> On Thu, Mar 27, 2025 at 02:03:21PM -0400, M Henning wrote: >> > On Thu, Mar 27, 2025 at 9:51 AM Danilo Krummrich <[email protected]> wrote: >> > > >> > > On Fri, Mar 21, 2025 at 06:06:34PM -0400, M Henning wrote: >> > > > On Thu, Mar 20, 2025 at 2:18 PM Danilo Krummrich <[email protected]> >> > > > wrote: >> > > > > On Wed, Mar 12, 2025 at 05:36:14PM -0400, Mel Henning wrote: >> > > > > > + __u32 width_align_pixels; >> > > > > > + __u32 height_align_pixels; >> > > > > > + __u32 pixel_squares_by_aliquots; >> > > > > > + __u32 aliquot_total; >> > > > > > + __u32 zcull_region_byte_multiplier; >> > > > > > + __u32 zcull_region_header_size; >> > > > > > + __u32 zcull_subregion_header_size; >> > > > > > + __u32 subregion_count; >> > > > > > + __u32 subregion_width_align_pixels; >> > > > > > + __u32 subregion_height_align_pixels; >> > > > > > + >> > > > > > + __u32 ctxsw_size; >> > > > > > + __u32 ctxsw_align; >> > > > > > +}; >> > > > > >> > > > > What if this ever changes between hardware revisions or firmware >> > > > > versions? >> > > > >> > > > There was some previous discussion of that here: >> > > > https://gitlab.freedesktop.org/mesa/mesa/-/issues/12596#note_2796853 >> > > > >> > > > From what I can tell, this structure hasn't really changed since >> > > > FERMI_C (circa 2011), so I'm not too worried about it changing on us >> > > > too quickly. When it does change, we have the option of appending more >> > > > members to this struct in the usual way, or if the change is more >> > > > fundamental we can return an error from this ioctl and add a new >> > > > interface. Userspace needs to handle an error from this ioctl >> > > > gracefully anyway since whether it works or not depends on the gpu >> > > > generation and what firmware is loaded right now. >> > > >> > > We could also define it as >> > > >> > > struct drm_nouveau_get_zcull_info { >> > > __u32 version; >> > > __u32 _pad; >> > > >> > > union { >> > > struct drm_nouveau_get_zcull_info_v1 info; >> > > } >> > > } >> > > >> > > just to be safe. >> > >> > We can do that, although I don't see any other drm drivers using a >> > similar pattern anywhere. >> >> I think it's a bit cleaner than adding new members, leave existing ones >> unset or >> add a new IOCTL in the worst case. >> >> Maybe the NVIDIA folks can give us some hint on whether this is expected to >> change at some point? > > I think it's an ioctl, let's just leave out version/pad, adding a new > ioctl isn't a major trouble if the world decides we need to do it. > > Also you can extend ioctls with new fields at the end without > problems, so if it's just extra info it'll likely be hw specific and > be part of enabling a new GPU.
Yeah, that's why I said "it's a bit cleaner than adding new members, leave existing ones unset or add a new IOCTL in the worst case" above. :) Anyways, this is quite a while ago and things have changed. I think we can afford to be a bit less future proof in terms of new GPU (and firmware) support. :)
