Re: [PATCH v4 4/7] drm: nova: Add a GPU info ioctl

On Tue Aug 11, 2026 at 7:06 AM CEST, Alistair Popple wrote:
> diff --git a/include/uapi/drm/nova_drm.h b/include/uapi/drm/nova_drm.h
> index ea7665383644..2604e4d2698b 100644
> --- a/include/uapi/drm/nova_drm.h
> +++ b/include/uapi/drm/nova_drm.h
> @@ -118,9 +118,34 @@ struct drm_nova_gem_info {
>  	__u64 size;
>  };
>  
> +/**
> + * struct drm_nova_gpu_info - query DRM GPU info.
> + */
> +struct drm_nova_gpu_info {
> +	/**
> +	 * @size: The amount of space allocated by userspace for this structure.
> +	 * The kernel will return the amount of data it did/could actually write.
> +	 * User space can use this to determine how much of the struct is valid
> +	 * when running against an older kernel.
> +	 */
> +	__u64 size;
> +
> +	/**
> +	 * @chipid: GPU chip identifier. See &enum drm_nova_chipid for currently
> +	 * known chip identifiers.
> +	 */
> +	__u32 chipid;
> +
> +	/**
> +	 * @pad: 32 bit padding, must be 0.
> +	 */
> +	__u32 pad;
> +};

I think we should add the indirection we discussed in [1], i.e. have an
indirection via

	struct drm_nova_info {
		__u32 id;
		__u32 size;
		__u64 info;
		/* Revserved fields, just in case? */
	};

so we can easily add new info structures, or extend an existing one with a v2
without having to create new ioctls for this purpose.

[1] https://lore.kernel.org/nova-gpu/[email protected]/

>  #define DRM_NOVA_GETPARAM		0x00
>  #define DRM_NOVA_GEM_CREATE		0x01
>  #define DRM_NOVA_GEM_INFO		0x02
> +#define DRM_NOVA_GPU_INFO		0x03
>  
>  /* Note: this is an enum so that it can be resolved by Rust bindgen. */
>  enum {
> @@ -130,6 +155,8 @@ enum {
>  						   struct drm_nova_gem_create),
>  	DRM_IOCTL_NOVA_GEM_INFO		= DRM_IOWR(DRM_COMMAND_BASE + DRM_NOVA_GEM_INFO,
>  						   struct drm_nova_gem_info),
> +	DRM_IOCTL_NOVA_GPU_INFO		= DRM_IOWR(DRM_COMMAND_BASE + DRM_NOVA_GPU_INFO,
> +						   struct drm_nova_gpu_info),
>  };
>  
>  #if defined(__cplusplus)
> -- 
> 2.54.0