[Mesa-dev] Can --enable-shared-glapi die?

[Jon TURNEY]

On 24/07/2012 02:08, Matt Turner wrote:
> On Mon, Jul 23, 2012 at 3:15 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> On 07/23/2012 12:59 PM, Ian Romanick wrote:
>>> Perhaps someone can refresh my memory as to what exactly this option
>>> does?  Can we make this the default and remove the option from configure?
>>
>> The --enable-shared-glapi option allows programs to use both libGL.so
>> and libGLESv2.so without zillions of conflicting linker symbols.  IIRC
>> it basically extracts the API dispatch stuff into libglapi.so and makes
>> both libraries depend on a single copy.
>>
>> I'm failing at email archaeology, but I know we've talked about this
>> before.  I believe Chia-I said he thought it would be a good idea to
>> make it the default, but essentially left the option as a chicken bit,
>> in case it didn't work in all situations.
>>
>> It looks like Matt Turner, Jon Turney, and Homer Hsing also approved of
>> the change.  Somebody had a patch but I can't find it now.
>>
>> The only trouble I know about is that if your libglapi gets out of sync
>> with your libGL/libGLES, all hell breaks loose: glCompileShader gets
>> routed to glLinkProgram and so on.  Apps fail in spectacular ways.  But
>> as long as you keep them in sync (and it's not hard), then it works fine.
>>
>> I'm all for making shared-glapi mandatory.  People who care about GLES
>> will want it (and thus distros would want it), there's no real downside,
>> and reducing the number of configurations would be great.
> 
> Yeah, I think I had a patch to make this mandatory. I'm also not
> remembering why it wasn't committed. It seems like there was some
> configuration (xlib-glx, osmesa, etc) that didn't work with
> shared-glapi.

Committed adefee50d954151f76150af80207081ae3c247d9 and reverted
027ce0c493a85c863df88b43f61aea34bcd4cd58

https://bugs.freedesktop.org/show_bug.cgi?id=45660 describes a part of the
breakage and it's fix.

Since it doesn't actually seem to be that well tested, perhaps making it the
default for a while before removing the option might be a good idea?

One could wish for a clearer diagnostic than all your GL programs getting
hilariously broken when using the wrong shared glapi, although I'm not sure
what sort of version check we could do.