Required backwards support level?

[Lauri Kasanen]

On Sun, 6 Apr 2014 19:58:48 +0200
Daniel Vetter <daniel at ffwll.ch> wrote:

> On Sun, Apr 6, 2014 at 7:28 PM, Lauri Kasanen <cand at gmx.com> wrote:
> > This is related to my memory management work. As the VRAM queue is
> > global, it cannot be determined on a per-app basis. If at least one
> > client is running old userspace, the new scoring cannot be used.
> >
> > Switching live between the two would bring additional complexity. I'd
> > hope to be able to determine by the first 3d app if the userspace is
> > new enough. But that depends on if it's expected to be able to run
> > mixed loads.
> 
> At least thus far we've worked under the example that any
> explicitly-enabled new behaviour is only enabled per-fd. That's also
> useful when you install all your developer versions into a prefix, so
> still have 2 versions of X driver, libdrm, mesa, everything else lying
> around and want to switch at runtime even.
> 
> Can't you fake a default score somehow for all legacy userspace and
> always run with the new code? Reimplementing the old interfaces in
> terms of the new ones also allows you to kick out duplicated code
> (usually) compared to having both old and new code around.

Certainly, that can be done. 

- Lauri