On 2012-03-15, Mike Pall<mikelu-1203@mike.de> wrote:
Henk Boom wrote:
I'm using LuaJIT 2.0.0-beta9 that I've checked out from git. My system
is Linux/x64 as well with a cpu that ubuntu lists as "Intel® Atom™ CPU
330 @ 1.60GHz × 4"
Well, I've got a Core2 E8400. But at this point CPU differences
shouldn't matter at all: the JIT compiler isn't invoked and the
interpreter is CPU-model-agnostic.
And I've tested with both the released beta9 and git HEAD. Same
(positive) result here.
I'm not sure what to try at this point. I know that I have support for
glCreateShader, since I've used it before in C/glut/glew programs. Is
there some other information I could capture that might make it easier
to debug the problem?
Try to recompile everything with debugging turned on and then set
a breakpoint at glCreateShader. You may have to wait for the
library to load and/or use the internal symbol name. Check the
argument it receives (in $rdi). Then set a breakpoint in the
calling frame and check the result it returns (in $rax).
Okay, so after trying to set a breakpoint I've figured out that the
ffi code is not actually calling glCreateShader. Printing the function
address returned from glXGetProcAddress from lua and from the
native-bound gl__glCreateShader tells me they have different
addresses. In particular, when I purposefully give glXGetProcAddress
an invalid name, it returns null in C, but from the ffi I always get
an address back.
I added these lines to gl__glCreateShader:
printf("glXGetProcAddress: %p\n", glXGetProcAddress);
printf("glXGetProcAddressARB: %p\n", glXGetProcAddressARB);
printf("glCreateShader: %p\n", glCreateShader);
and these to init.lua
print('glXGetProcAddress', libgl.glXGetProcAddress)
print('glCreateShader', libgl.glXGetProcAddress('glCreateShader'))
The output I get is a bit different every time, but here's an example:
--------
glfwInit 1
glfwOpenWindow 1
glfw version 2 6 0
opengl version 0.0
this doesn't work
glXGetProcAddress cdata<void (*())()>: 0x7f4a6c406d50
glCreateShader cdata<void (*)()>: 0x7f4a6c1d6820
glCreateShader 0
this does
glXGetProcAddress: 0x7f4a6fe09330
glXGetProcAddressARB: 0x7f4a6fe09440
glCreateShader: 0x7f4a70088060
glCreateShader 1
--------
I'm not sure how those numbers make sense. Maybe I just don't
understand how these symbols are resolved at load/run-time, but I
would expect the lua-printed address of glXGetProcAddress to match
with the c-printed one.
henk
