On Mon, Nov 18, 2013 at 10:23 AM, Thierry Reding <thierry.reding@xxxxxxxxx> wrote: > On Mon, Nov 18, 2013 at 10:17:47AM -0500, Rob Clark wrote: >> On Mon, Nov 18, 2013 at 8:29 AM, Thierry Reding >> <thierry.reding@xxxxxxxxx> wrote: >> > On Sat, Nov 09, 2013 at 01:26:24PM -0800, Ian Romanick wrote: >> >> On 11/09/2013 12:11 AM, Dave Airlie wrote: >> >> >>> How does this interact with the rule that kernel interfaces require an >> >> >>> open source userspace? Is "here are the mesa/libdrm patches that use >> >> >>> it" sufficient to get the kernel interface merged? >> >> >> >> >> >> That's my understanding: open source userspace needs to exist, but it >> >> >> doesn't need to be merged upstream yet. >> >> > >> >> > Having an opensource userspace and having it committed to a final repo >> >> > are different things, as Daniel said patches on the mesa-list were >> >> > sufficient, they're was no hurry to merge them considering a kernel >> >> > release with the code wasn't close, esp with a 3 month release window >> >> > if the kernel merge window is close to that anyways. >> >> > >> >> >>> libdrm is easy to change and its releases are cheap. What problem does >> >> >>> committing code that uses an in-progress kernel interface to libdrm >> >> >>> cause? I guess I'm not understanding something. >> >> >> >> >> > >> >> > Releases are cheap, but ABI breaks aren't so you can't just go release >> >> > a libdrm with an ABI for mesa then decide later it was a bad plan. >> >> > >> >> >> Introducing new kernel API usually involves assigning numbers for things >> >> >> - a new ioctl number, new #defines for bitfield members, and so on. >> >> >> >> >> >> Multiple patches can be in flight at the same time. For example, Abdiel >> >> >> and I both defined execbuf2 flags: >> >> >> >> >> >> #define I915_EXEC_RS (1 << 13) (Abdiel's code) >> >> >> #define I915_EXEC_OA (1 << 13) (my code) >> >> >> >> >> >> These obviously conflict. One of the two will land, and the second >> >> >> patch author will need to switch to (1 << 14) and resubmit. >> >> >> >> >> >> If we both decide to push to libdrm, we might get the order backwards, >> >> >> or maybe one series won't get pushed at all (in this case, I'm planning >> >> >> to drop my patch). Waiting until one lands in the kernel avoids that >> >> >> problem. Normally, I believe we copy the kernel headers to userspace >> >> >> and fix them up a bit. >> >> >> >> >> >> Dave may have other reasons; this is just the one I thought of. >> >> > >> >> > But mostly this, we've been stung by this exact thing happening >> >> > before, and we made the process to stop it from happening again. >> >> >> >> Then in all honestly, commits to libdrm should be controlled by either a >> >> single person or a small cabal... just like the kernel and the xserver. >> >> We're clearly in an uncomfortable middle area where we have a stringent >> >> set of restrictions but no way to actually enforce them. >> > >> > That doesn't sound like a bad idea at all. It obviously causes more work >> > for whoever will be the gatekeeper(s). >> > >> > It seems to me that libdrm is currently more of a free-for-all type of >> > project, and whoever merges some new feature required for a particular X >> > or Mesa driver cuts a new release so that the version number can be used >> > to track the dependency. >> > >> > I wonder if perhaps tying the libdrm releases more tightly to Linux >> > kernel releases would help. Since there already is a requirement for new >> > kernel APIs to be merged before the libdrm equivalent can be merged, >> > then having both release cycles in lockstep makes some sense. >> >> Not sure about strictly tying it to kernel releases would be ideal. >> Not *everything* in libdrm is about new kernel APIs. It tends to be >> the place for things needed both by xorg ddx and mesa driver, which I >> suppose is why it ends up a bit of a free-for-all. > > I didn't mean that every release would need to be tied to the Linux > kernel. But whenever a new Linux kernel release was made, relevant > changes from the public headers could be pulled into libdrm and a > release be made. I could even imagine a matching of version numbers. > libdrm releases could be numbered using the same major and minor as > Linux kernels that they support. Micro version numbers could be used > in intermediate releases. maybe an update-kernel-headers.sh script to grab the headers from drm-next and update libdrm wouldn't be a bad idea? >> Maybe limiting who does releases would be sufficient. Unless there is >> someone with enough free time and energy to volunteer to be libdrm >> maintainer. >> >> But tbh I don't think it has been too much of a problem in the past. >> I'm not sure if I actually read somewhere the rule about not updating >> kernel headers until the interface is locked in (ie. drm-next), but it >> seemed like common sense to me. Could be enough just to document this >> a bit more explicitly. > > It's not something I feel very strongly about. People seemed unhappy > about the current state of affairs, so I thought I'd dump a few ideas. > =) > > Thierry _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
