Hi everyone, I have run into a problem leading to a crashing X server for a bunch of indirect GLX calls.
This problem affects any OpenGL clients using indirect rendering and calling functions which are outside the ABI. Problems range from malfunctioning to crashes. Problem analysis: The dispatcher functions in glx/indirect_dispatch.c demarshall the function arguments from the GLX wire protocol and then call the appropriate function of the GL library. Function calls are done using dispatch table with the help of the CALL_* helper macros defined in dispatch.h. Unfortunately there is a mismatch between the dispatch table expected by the xserver - which follows the layout e.g. found in glapitable.h - and the one provided by the GL library, e.g. Mesa. Although both tables are created from the definitions in the various xml files part of Mesa, the xserver table omits the slots for the EGL methods and various others. Possible solutions: 1. Use the approach used by XQuartz, i.e. allocate a table und fill the slots using dlsym. Pros: works independend on X/Mesa version, no additional runtime cost Cons: increased startup time 2. Make sure the Xserver uses the same table layout, i.e. insert some empty slots in the right positions. Pros: no additional runtime or setup cost Cons: new slots must only be appended to the table 3. Use the remap table Pros: adapts to changes in the GL library Cons: needs the (mesa internal) remap table, i.e. only applicable to Mesa, runtime cost due to the extra level of indirection. Which would be the preferred approach, are there any other? A bug has been filed against the Xserver: https://bugs.freedesktop.org/show_bug.cgi?id=61022 Regards, Stefan -- Stefan Brüns / Bergstraße 21 / 52062 Aachen phone: +49 241 53809034 mobile: +49 151 50412019 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
