[Mesa-dev] Understanding GLX_INDIRECT_RENDERING (libOSMesa fails to link due to gl_dispatch_stub*)
brianp at vmware.com
Tue Jun 7 11:13:28 PDT 2011
On 06/07/2011 11:26 AM, Jeremy Huddleston wrote:
> On Jun 7, 2011, at 1:01 PM, Jeremy Huddleston wrote:
>> On Jun 7, 2011, at 12:01 PM, Jeremy Huddleston wrote:
>>> So what is the proper fix here? How should libOSMesa be getting built?
>>> Should libmesa.a be providing those stubs (rather than my change which put them in mesa/osmesa)? Should the stubs be getting exported by libGL? Should GetHistogramEXT be exported by libGL?
>>> Based on my understanding, it seems like we should bring these stubs into libmesa.a (and remove them from mesa/xlib). Does that sound right?
>> Actually... I'm perplexed about another issue here... why is libOSMesa linking against both libglapi and libGL?
>> It seems like the only things resolving into libGL are the stub symbols missing in libglapi. If we provide them in osmesa, why does libOSMesa need to link against libGL at all?
>> Similarly, libOSMesa seems to build fine if I just don't include libglapi.a and let it resolve those calls into libGL (which it can re-export to provide the gl* entry points). This of course requires libGL to be glapi-aware (which glx/apple isn't yet).
>> As is, including libglapi.a in libOSMesa and in libGL will result in two copies of libglapi existing in memory which seems like a recipe for disaster since there will be two different dispatch tables, etc. Perhaps this isn't a problem on systems with flat namespaces, but on darwin, it is.
> Ok, I see what is happening. configs/darwin bitrotted and included the -lGL, but other configs have since removed that. It looks like I should just remove -lGL from OSMESA_LIB_DEPS in addition to the other changes that I've already sent for osmesa.c
> It looks like -lGL is still done in default, beos, and aix ... so someone might want to update those as well...
At one time, I had things set up so that one libGL.so contained both
the GLX and OSMesa interfaces. An app could create a context of each
time and freely switch between them with glX/OSMesa-MakeCurrent(). A
while back this got changed so the OSMesa stuff lives in its own
At first glance, I'd suggest just omitting all the OSMesa stuff on
Darwin for now.
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