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

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 31/7/24 17:41, Peter Maydell wrote:
> 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>
> ---
>   hw/display/virtio-gpu-gl.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>