On 09/05/2018 03:07 PM, Emil Velikov wrote:
On 5 September 2018 at 11:10, Thomas Hellstrom thellstrom@vmware.com wrote:
Hi, Emil,
On 09/05/2018 11:33 AM, Emil Velikov wrote:
On 4 September 2018 at 23:33, Dave Airlie airlied@gmail.com wrote:
On Tue, 4 Sep 2018 at 03:00, Thomas Hellstrom thellstrom@vmware.com wrote:
On 09/03/2018 06:33 PM, Daniel Vetter wrote:
On Mon, Sep 03, 2018 at 11:16:29AM +0200, Thomas Hellstrom wrote: > On 08/31/2018 05:30 PM, Thomas Hellstrom wrote: >> On 08/31/2018 05:27 PM, Emil Velikov wrote: >>> On 31 August 2018 at 15:38, Michel Dänzer michel@daenzer.net >>> wrote: >>>> [ Adding the amd-gfx list ] >>>> >>>> On 2018-08-31 3:05 p.m., Thomas Hellstrom wrote: >>>>> On 08/31/2018 02:30 PM, Emil Velikov wrote: >>>>>> On 31 August 2018 at 12:54, Thomas Hellstrom >>>>>> thellstrom@vmware.com >>>>>> wrote: >>>>>>> To determine whether a device node is a drm device >>>>>>> node or not, the code >>>>>>> currently compares the node's major number to the static drm >>>>>>> major >>>>>>> device >>>>>>> number. >>>>>>> >>>>>>> This breaks the standalone vmwgfx driver on XWayland dri >>>>>>> clients, >>>>>>> >>>>>> Any particular reason why the code doesn't use a fixed node >>>>>> there? >>>>>> It will make the diff vs the in-kernel driver a bit smaller. >>>>> Because then it won't be able to interoperate with other in-tree >>>>> drivers, like virtual drm drivers or passthrough usb drm drivers. >>>>> There is no clean way to share the minor number allocation >>>>> with in-tree >>>>> drm, so standalone vmwgfx is using dynamic major allocation. >>>> I wonder why I haven't heard of any of these issues with the >>>> standalone >>>> version of amdgpu shipped in packaged AMD releases. Does that >>>> also use a >>>> different major number? If yes, maybe it's just that nobody has >>>> tried >>>> Xwayland clients with that driver. If no, how does it avoid the >>>> other >>>> issues described above? >>>> >>> AFAICT, the difference is that the standalone vmwgfx uses an >>> internal >>> copy of drm core. >>> It doesn't reuse the in-kernel drm, hence it cannot know which minor >>> it can use. >>> >>> -Emil >> Actually, standalone vmwgfx could perhaps also try to allocate minors >> from 63 and downwards. That might work, but needs some verification. >> > So unfortuntately this doesn't work since the in-tree drm's file > operations > are registered with the DRM_MAJOR. > So I still think the patch is the way to go. If people are concerned > that > also fbdev file descriptors are allowed, perhaps there are other sysfs > traits we can look at? Somewhat out of curiosity, but why do you have to overwrite all of drm? amdgpu seems to be able to pull their stunt off without ... -Daniel
At the time we launched the standalone vmwgfx, the DRM <-> driver interface was moving considerably more rapidly than the DRM <-> kernel interface. I think that's still the case. Hence less work for us. Also meant we can install the full driver stack with latest features on fairly old VMs without backported DRM functionality.
I think this should be fine for 99% of drm usage, there may be corner cases in wierd places, but I can't point to any that really matter (maybe strace?)
Having a closer look, I think this will break the Firefox/Chrome sandboxing :-\ I cannot see the path /sys/dev/char/%d:%d/device/drm in the allowed list [1] [2].
Thanks for pointing this out.
The function drmGetMinorNameForFD() already opens this path, so any user-space using that function would not work before either.
Also mozilla/firefox adds /sys/dev/char/226:* Which means that while it still won't work on standalone vmwgfx, there should at least be no regression.
For Chromium it seems they allow /sys/dev/char/ for AmdGpu, but only under ChromOS, so I'll ping those to be safe.
I also won't be doing an immediate release after pushing.
In that case, please give me 24h to do a libdrm release before pushing. I had to push some workarounds for the sandboxing mentioned earlier :-\
Thanks Emil
Ouch, I just pushed the patch, but feel free to cut the release just before that commit.
/Thomas