Re: [PATCH v6 3/4] drm: Expand max DRM device number to full MINORBITS

[Christian König]

Am 26.07.23 um 20:15 schrieb Simon Ser:
> On Monday, July 24th, 2023 at 23:14, Michał Winiarski <michal.winiarski@xxxxxxxxx> wrote:
>
> > Having a limit of 64 DRM devices is not good enough for modern world
> > where we have multi-GPU servers, SR-IOV virtual functions and virtual
> > devices used for testing.
> > Let's utilize full minor range for DRM devices.
> > To avoid regressing the existing userspace, we're still maintaining the
> > numbering scheme where 0-63 is used for primary, 64-127 is reserved
> > (formerly for control) and 128-191 is used for render.
> > For minors >= 192, we're allocating minors dynamically on a first-come,
> > first-served basis.
> In general the approach looks good to me. Old libdrm will see the new
> nodes as nodes with an unknown type when it tries to infer the nod type
> from the minor, which is as good as it gets.

Yeah, agree. I wouldn't upstream patch #4, but apart from that it looks 
like it shouldn't break anything which wasn't broken before.

> We do need patches to stop trying to infer the node type from the minor
> in libdrm, though. Emil has suggested using sysfs, which we already do
> in a few places in libdrm.

That sounds like a really good idea to me as well.

But what do we do with DRM_MAX_MINOR? Change it or keep it and say apps 
should use drmGetDevices2() like Emil suggested?

Regards,
Christian.