Re: [PATCH] drm/i915/dmc: Accept symbolic link in firmware name

Imre Deak
2016-07-11T14:02:04Z

On ma, 2016-07-11 at 14:50 +0100, chris@chris-wilson.co.uk wrote:
> On Mon, Jul 11, 2016 at 04:24:50PM +0300, Imre Deak wrote:
> > On ma, 2016-07-11 at 13:55 +0100, chris@chris-wilson.co.uk wrote:
> > > And then you get random changes in the firmare whilst bisecting
> > > the
> > > kernel.
> >
> > What do you mean random? During bisecting we want to load the
> > firmware
> > version that was used with a particular commit. With a symlink
> > pointing
> > to the wrong firmware file for a given commit, we'd fail loading
> > the
> > firmware due to the version check and hide/introduce bugs for that
> > commit.
>
> No. You want to be changing exactly one variable, which means leaving
> the firmware constant.

Hm, not sure. When looking for a working snapshot you also want to
consider bugs introduced by the firmware itself. This is in a way the
exact reason why we want stricter control on the firmware version and
introduced a white list. This also means that loading a firmware
version other than what the driver allows (at a given commit) won't
work anyway.

> The firmware should be side-ways compatible for
> everything with the same minor version (thus resolvable from the same
> symlink), right?

From the same major version I guess it should, but the reason things
don't work that way is why we introduced version white listing.

--Imre