[Mesa-dev] [PATCH mesa 03/10] egl+glx: turn LIBGL_ALWAYS_SOFTWARE into a boolean

[Eric Engestrom]

On Friday, 2017-09-08 08:13:54 -0700, Kenneth Graunke wrote:
> On Friday, September 8, 2017 6:33:44 AM PDT Emil Velikov wrote:
> > Hi Eric,
> > 
> > On 8 September 2017 at 13:40, Eric Engestrom <eric.engestrom at imgtec.com> wrote:
> > > Instead of setting based on set/unset, allow users to use boolean values.
> > > In the docs, use `ALWAYS=true` instead of `ALWAYS=1` as it's clearer IMO.
> > >
> > I'm a bit weary about this series. In the past we had cases where
> > people will set the variable to empty string and/or 0 and expect
> > things to work.
> > 
> > IIRC the older Intel QA team was using it, not sure about now. Either
> > way it's great to confirm with a few people before pushing this.
> 
> That team is gone.  I like the consistency of using env_var_as_boolean
> across the codebase - it might break a few things, but I think that's
> okay.  Most people don't use this, and most of those that do use =1.

Agreed.

> 
> > That aside, env_var_as_boolean() treats 'yes', '1' and 'true' in
> > identical manner. Perhaps we can state what a "boolean variable" is
> > and use that reference through the documentation?
> > 
> > -Emil
> 
> That seems like a good idea.

Yes indeed, and I'll do that, but as a follow up patch.
I'm thinking of adding something like this at the top of envvar.html:

	There are different kind of environment variables:
	  - BOOL: expects 1/true/yes or 0/false/no.
	  - INT: expects an integer value.
	  - ENUM: expects an string, but only a limited set of values is accepted.
	  - PATH: expects a file or folder path.
	  - NAME: expects a string name (like a driver name), but not a full path.
	  - NON-NULL: any value enables it (including empty string); use `unset` to disable.
	Note: some variables expect more complicated values, like
	MESA_EXTENSION_OVERRIDE.

and then each env var in the doc would get an annotation:
	LIBGL_ALWAYS_SOFTWARE (BOOL)
	LIBGL_SHOW_FPS (INT)
	EGL_LOG_LEVEL (ENUM: debug, info, warning, fatal)
	EGL_DRIVERS_PATH (PATH)
	EGL_DRIVER (PATH or NAME)
	EGL_PLATFORM (NAME)
... etc.

Hopefully, this should be clear enough. The last option (NON-NULL) would
be applied to the old-style toggles.

For now, there seems to be another issue; I sent this series to travis,
and EGL is failing to link [1] because every exported symbol in mesautil
appears twice; some sort of double-link issue?
I don't know if I'm tired or thick, but I can't figure it out :]

[1] https://travis-ci.org/1ace/mesa/jobs/273302410#L6797

I'd appreciate any help :)

Cheers,
  Eric