> This doesn't sound like a good idea to me. Devices without render > capabilities should not fake it. > > User-space (e.g. wlroots) relies on "no render node" to enable > software rendering (Pixman instead of GL). We have virtgpu driver that exports a render node even when virgl is not supported. Mesa has special code path to enable software rendering on it: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/egl/drivers/dri2/platform_device.c#L296 We can do the same for vkms to force software rendering. On Thu, Jan 5, 2023 at 8:36 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Thu, Jan 05, 2023 at 02:23:25PM +0900, Yi Xie wrote: > > Some libraries including Mesa and virglrenderer require a render node to > > fully function. By adding a render node to vkms those libraries will > > work properly, supporting use cases like running crosvm with virgl GPU > > support via llvmpipe on a headless virtual machine. > > This is what vgem exists for. More or less at least ... I'm honestly not > really understanding what you're trying to fix here, it sounds a bit like > userspace being stupid. > -Daniel The problem with vgem is that it crashes llvmpipe while working with vkms. Looks like it's due to the same reason as described in this thread in Mesa: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5830 Importing buffers allocated by vgem to vkms seems to be unexpected and causes the crash. If we create a render node on vkms then llvmpipe will use vkms to allocate buffers and it no longer crashes. > > > > Signed-off-by: Yi Xie <yixie@xxxxxxxxxx> > > --- > > drivers/gpu/drm/vkms/vkms_drv.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c > > index 293dbca50c31..8eea5d4dece8 100644 > > --- a/drivers/gpu/drm/vkms/vkms_drv.c > > +++ b/drivers/gpu/drm/vkms/vkms_drv.c > > @@ -113,7 +113,7 @@ static void vkms_config_debugfs_init(struct drm_minor *minor) > > } > > > > static const struct drm_driver vkms_driver = { > > - .driver_features = DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM, > > + .driver_features = DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM | DRIVER_RENDER, > > .release = vkms_release, > > .fops = &vkms_driver_fops, > > DRM_GEM_SHMEM_DRIVER_OPS, > > -- > > 2.39.0.314.g84b9a713c41-goog > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
