wlroots multi-gpu support does not work on QEMU

[n3rdopolis]

I have been asked to open this issue separately. However, https://github.com/swaywm/wlroots/commit/2d8f53affd586709fe568b0b16e4c7e215d9db7a fixed the problem with the VGA driver, now it doesn't crash, but it reports that PRIME import isn't supported, so that must be an issue with the driver itself.

However, trying with two 'qxl' cards and it still aborts

pci id for fd 9: 1b36:0100, driver (null)
pci id for fd 10: 1b36:0100, driver (null)
2018-08-07 10:15:59 - [EGL] eglCreateImageKHR: dri2_create_image_khr_texture
sway: ../backend/drm/renderer.c:221: copy_drm_surface_mgpu: Assertion `tex' failed.

I am not sure what else I need to provide. It might be hard to attach a debugger to it, however, you can simulate two GPUs with

qemu-system-x86_64 -m 2047  -vga qxl -enable-kvm \
-device qxl \
-spice port=5930,disable-ticketing -cpu host \
&
remote-viewer spice://127.0.0.1:5930

You need to use spice and remote-viewer, as that's how to get and see the output of multiple GPUs on QEMU

---

wlroots has migrated to gitlab.freedesktop.org. This issue has been moved to:

https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/1181