Hi
On Thu, Jul 11, 2013 at 1:12 PM, Martin Peres martin.peres@labri.fr wrote:
On 07/07/2013 19:17, David Herrmann wrote:
Hi
This is v2 of the unified VMA offset manager series. The first draft is available at LWN [1]. This series replaces the VMA offset managers in GEM and TTM with a unified implementation.
The first 4 patches contain the new VMA offset manager and are the only patches that I propose for mainline inclusion. Patches 5-8 clean up drm_mm and are informational-only. Daniel has similar patches in i915-next and I will rebase them once it is merged. Ignore them if you're not interested. Patches 9-19 implement mmap access control. Comments are welcome! They are intended for mainline inclusion, too, but probably require some more review rounds. I'd really appreciate if driver authors could comment on the implementation. Patch 20 shows the main motivation behind this whole series: render nodes. It is marked RFC and I will resend once the VMA manager is merged upstream. Feel free to test it.
One more note regarding DRM-Master: Render-clients are independent of DRM-Master (see the DocBook documentation). It really doesn't make sense to create/bind a DRM-Master object to render-clients. However, a lot of core DRM code depends on ->master != NULL. Drivers need to take care not to call into those core modules if they implement DRIVER_RENDER. I plan on removing multiple-master-support in the next series. So there will be only one global master and each open-file is bound to it. This will make it very easy to phase out "drm_master". The planned "modeset" nodes provide a nice replacement. If anyone knows a **currently used** use-case for multiple-masters, please tell me. I couldn't find one that _actually works_. (SetMaster+DropMaster will obviously stay functional even with drm_master removed).
(series available at: https://github.com/dvdhrm/linux/tree/rnodes)
Comments welcome! Cheers David
Hi David,
Thanks for this patchset. I am away from my computers for testing but I was wondering if you based your vma rework on Dave's implementation. If so, you may have the same bug that I had with it.
I cannot remember the details of the bug, but I could trigger it by rebooting kde around 13 times on radeon. I didn't have this problem with Nouveau.
It is based on Dave's code, but I rewrote all of it and fixed several bugs. For instance, there was a TTM ref-count leak for BOs in TTM core and a TTM locking issue. I didn't encounter any bugs so far, but I didn't try to restart the xserver 13 times. I will do some more stress-tests, but it is quite likely you hit one of those two bugs with radeon.
I am not competent to judge this work but I will try to test it and check with my security tests that I wrote that the problem is indeed solved on nouveau and radeon.
The changes are actually quite simple. I intentionally kept TTM locking as it was before, even though I think we could reduce it now. Anyway, I will resend v3 (which now includes tegra and staging) this weekend. Hopefully we can get it into linux-next soon.
Thanks! David
Looking forward to seeing your proposition for the userspace :)
Cheers, Martin