Re: [PATCH v5 05/11] drm: nova: Add an info ioctl

[Dave Airlie]

On Fri, 28 Aug 2026 at 13:36, Alistair Popple <apopple@xxxxxxxxxx> wrote:
>
> Add an extensible info ioctl and use it to report basic GPU information.
> One of the first things userspace needs to know about a GPU is its
> architecture and implementation, so add that as the first field in the
> GPU info result.
>
> The ioctl selects an information type by ID and writes the result through
> a sized userspace buffer. The kernel truncates results to the supplied
> size, allowing information structures to grow and new logical information
> groups to be added without introducing new ioctls.
>
>

This is a higher level for the future, I think we have two paths for
getparam type ioctl.

Either we expose a big struct full of values with a add to the end
mentality or we keep a long list of value pairs, and userspace passes
in a list of value keys, and we return a list of the values.

I'm trying to think ahead towards native virtio context support, and I
think having the sequence,

open
get_all_infos
create vm/channel

might have the most optimal ioctl count but also let power management
avoid booting the GPU on every open if we never create a vm/channel.

Dave.