[PATCH 2/3] drm/uapi: add explicit virtgpu context debug name

[Dmitry Osipenko]

On 10/16/23 21:41, Gurchetan Singh wrote:
> There are two problems with the current method of determining the
> virtio-gpu debug name.
> 
> 1) TASK_COMM_LEN is defined to be 16 bytes only, and this is a
>    Linux kernel idiom (see PR_SET_NAME + PR_GET_NAME). Though,
>    Android/FreeBSD get around this via setprogname(..)/getprogname(..)
>    in libc.
> 
>    On Android, names longer than 16 bytes are common.  For example,
>    one often encounters a program like "com.android.systemui".
> 
>    The virtio-gpu spec allows the debug name to be up to 64 bytes, so
>    ideally userspace should be able to set debug names up to 64 bytes.
> 
> 2) The current implementation determines the debug name using whatever
>    task initiated virtgpu.  This is could be a "RenderThread" of a
>    larger program, when we actually want to propagate the debug name
>    of the program.
> 
> To fix these issues, add a new CONTEXT_INIT param that allows userspace
> to set the debug name when creating a context.
> 
> It takes a null-terminated C-string as the param value.
> 
> Link to open-source userspace:
> https://android-review.googlesource.com/c/platform/hardware/google/gfxstream/+/2787176
> 
> Signed-off-by: Gurchetan Singh <gurchetansingh at chromium.org>
> ---
>  include/uapi/drm/virtgpu_drm.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
> index b1d0e56565bc..c2ce71987e9b 100644
> --- a/include/uapi/drm/virtgpu_drm.h
> +++ b/include/uapi/drm/virtgpu_drm.h
> @@ -97,6 +97,7 @@ struct drm_virtgpu_execbuffer {
>  #define VIRTGPU_PARAM_CROSS_DEVICE 5 /* Cross virtio-device resource sharing  */
>  #define VIRTGPU_PARAM_CONTEXT_INIT 6 /* DRM_VIRTGPU_CONTEXT_INIT */
>  #define VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs 7 /* Bitmask of supported capability set ids */
> +#define VIRTGPU_PARAM_EXPLICIT_DEBUG_NAME 8 /* Ability to set debug name from userspace */
>  
>  struct drm_virtgpu_getparam {
>  	__u64 param;
> @@ -198,6 +199,7 @@ struct drm_virtgpu_resource_create_blob {
>  #define VIRTGPU_CONTEXT_PARAM_CAPSET_ID       0x0001
>  #define VIRTGPU_CONTEXT_PARAM_NUM_RINGS       0x0002
>  #define VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK 0x0003
> +#define VIRTGPU_CONTEXT_PARAM_DEBUG_NAME      0x0004
>  struct drm_virtgpu_context_set_param {
>  	__u64 param;
>  	__u64 value;

Please squash it into the next patch. UAPI changes shouldn't be
separated from the code that uses this UAPI.

-- 
Best regards,
Dmitry