On Thu, 09 May 2024, nerdopolis <bluescreen_aven...@verizon.net> wrote: > Hi > > So I have been made aware of an apparent race condition of some drivers > taking a bit longer to load, which could lead to a possible race condition of > display servers/greeters using the simpledrm device, and then experiencing > problems once the real driver loads, the simpledrm device that the display > servers are using as their primary GPU goes away. > > For example Weston crashes, Xorg crashes, wlroots seems to stay running, but > doesn't draw anything on the screen, kwin aborts, > This is if you boot on a QEMU machine with the virtio card, with > modprobe.blacklist=virtio_gpu, and then, when the display server is running, > run sudo modprobe virtio-gpu > > Namely, it's been recently reported here: > https://github.com/sddm/sddm/issues/1917[1] and here > https://github.com/systemd/systemd/issues/32509[2] > > My thinking: Instead of simpledrm's /dev/dri/card0 device going away when the > real driver loads, is it possible for simpledrm to instead simulate an unplug > of the fake display/CRTC? > That way in theory, the simpledrm device will now be useless for drawing for > drawing to the screen at that point, since the real driver is now taken over, > but this way here, at least the display server doesn't lose its handles to > the /dev/dri/card0 device, (and then maybe only remove itself once the final > handle to it closes?) > > Is something like this possible to do with the way simpledrm works with the > low level video memory? Or is this not possible?
Related [1][2]. BR, Jani. [1] https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10133 [2] https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11158 > > Thanks > > -------- > [1] https://github.com/sddm/sddm/issues/1917 > [2] https://github.com/systemd/systemd/issues/32509 -- Jani Nikula, Intel
