[Mesa-dev] [PATCH] loader: disable virgl driver when no 3D for virtio

[Ilia Mirkin]

Shouldn't this just be handled as in, e.g.,

https://cgit.freedesktop.org/mesa/mesa/tree/src/gallium/winsys/nouveau/drm/nouveau_drm_winsys.c#n97

i.e. return an error in the driver-specific loader? This create
function should fail:

https://cgit.freedesktop.org/mesa/mesa/tree/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c#n897

On Thu, Apr 5, 2018 at 1:16 AM, Lepton Wu <lepton at chromium.org> wrote:
> If user are running mesa under old version of qemu or have turned off
> GL at runtime, virtio gpu driver actually doesn't work. Adding a detection
> here can make sure same disk image work with both cases.
>
> Signed-off-by: Lepton Wu <lepton at chromium.org>
> ---
>  src/loader/loader.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/src/loader/loader.c b/src/loader/loader.c
> index 43275484cc..2a689c52d6 100644
> --- a/src/loader/loader.c
> +++ b/src/loader/loader.c
> @@ -381,6 +381,27 @@ out:
>     log_(driver ? _LOADER_DEBUG : _LOADER_WARNING,
>           "pci id for fd %d: %04x:%04x, driver %s\n",
>           fd, vendor_id, chip_id, driver);
> +   if (!strcmp(driver, "virtio_gpu")) {
> +      struct drm_virtgpu_getparam {
> +         uint64_t param;
> +         uint64_t value;
> +      };
> +      #define VIRTGPU_PARAM_3D_FEATURES 1 /* do we have 3D features in the hw */
> +      struct drm_virtgpu_getparam args;
> +      uint32_t gl = 0;
> +      args.param = VIRTGPU_PARAM_3D_FEATURES;
> +      args.value = (uint64_t)(uintptr_t)≷
> +      #define DRM_VIRTGPU_GETPARAM    0x03
> +      #define DRM_IOCTL_VIRTGPU_GETPARAM \
> +         DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_GETPARAM,\
> +                  struct drm_virtgpu_getparam)
> +      int ret = drmIoctl(fd, DRM_IOCTL_VIRTGPU_GETPARAM, &args);
> +      if (ret || !gl) {
> +         /* Actually there is no virtio_2d driver, mesa will
> +          * fallback to software driver */
> +         return strdup("virtio_gpu_2d");
> +      }
> +   }
>     return driver;
>  }
>
> --
> 2.17.0.484.g0c8726318c-goog
>
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