Re: [PATCH 1/3] hw/display/virtio-gpu: Improve "opengl is not available" error message

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> If the user tries to use the virtio-gpu-gl device but the display
> backend doesn't have OpenGL support enabled, we currently print a
> rather uninformative error message:
>
> $ qemu-system-aarch64 -M virt -device virtio-gpu-gl
> qemu-system-aarch64: -device virtio-gpu-gl: opengl is not available
>
> Since OpenGL is not enabled on display frontends by default, users
> are quite likely to run into this. Improve the error message to
> be more specific and to suggest to the user a path forward.
>
> Note that the case of "user tried to enable OpenGL but the display
> backend doesn't handle it" is caught elsewhere first, so we can
> assume that isn't the problem:
>
> $ qemu-system-aarch64 -M virt -device virtio-gpu-gl -display curses,gl=on
> qemu-system-aarch64: OpenGL is not supported by the display
>
> (Use of error_append_hint() requires us to add an ERRP_GUARD() to
> the function, as noted in include/qapi/error.h.)
>
> With this commit we now produce the hopefully more helpful error:
> $ ./build/x86/qemu-system-aarch64 -M virt -device virtio-gpu-gl
> qemu-system-aarch64: -device virtio-gpu-gl: The display backend does not have OpenGL support enabled
> It can be enabled with '-display BACKEND,gl=on' where BACKEND is the name of the display backend to use.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2443
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro