On Wednesday 20 March 2013 15:47:24 you wrote: > On 03/20/2013 02:43 PM, Stefan Brüns wrote: > > On Tuesday 12 March 2013 09:25:07 Ian Romanick wrote: > >> On 03/10/2013 11:24 AM, Stefan Brüns wrote: > >>> 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. > >> > >> The dependency is the other way around. The loader (either libGL on the > >> client or the GLX extension in the server) dictates the layout of the > >> dispatch table. The GL driver is required to adapt to the layout > >> dictated by the loader. That's the whole reason the remap table exists. > >> > >> The driver queries the loader to learn where functions are located in > >> > >> the dispatch table. It then stores the dispatch table locations at > >> (fixed) locations in the remap table. So, the driver knows that glFoo > >> is at location 824 in the remap table, and that entry stores the > >> location of glFoo in the dispatch table. > >> > >> It sounds like something else is going wrong. > > > > Currently this obviously can not work. > > > > The remap table is only used when FEATURE_remap_table is defined, which > > for > > the X server is never true. > > > > Now, lets try defining FEATURE_remap_table for the xserver (which breaks > > OS X and windows builds of Mesa, but anyway ...) > > Xserver has nothing to do with it. The remap table is entirely in the > driver (*_dri.so). The xserver has no knowledge about the remap table > whatsoever. The xserver only knows about the dispatch table, and it > dictates where things are in that table. > > It's been a long time since I wrote this code, but I haven't been able > to kill of all the memories of it yet. :)
Please, look at the code again as I have done! The x server code found in xorg/glx/indirect_dispatch.c directly call into the dispatch table, and it uses the offsets found in xorg/glx/dispatch.h 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
