segfault in multithread OpenGL app on i915

[Nickolay Kolchin]

Hello,

I have a weird problem with multithread application on i915 chipset
(i810 DRI driver). Application segfaults when trying to use OpenGL
functions from second thread.

All necessary initialization is perfomed in application, ie XInitThreads, etc.

Tested on Suse 10.1 (xorg 6.8, 20050225 i810 driver) and Gentoo
LiveDVD (xorg 7.0, 1.4.2 i810 driver).

This code works fine with NVidia drivers. (for several years)

Is this a driver bug? a Mesa bug? a well-known bug that nobody is
going to fix in near future? Or this is my programming error?

[code]
static void* cbOpenglTest1(void*)
{
  while(1)
  {
    XLockDisplay(display);
    if(!glXMakeCurrent(display, x_win, x_glxContext))
    {
      printf("glXMakeCurrent failed\n");
      exit(0);
    }
    int err = glGetError(); // <- SEGFAULT here :(
    L_INFO("OpenGL Error: %i", err);
    if(!glXMakeCurrent(display, 0, 0))
    {
      printf("glXMakeCurrent failed\n");
      exit(0);
    }
    XUnlockDisplay(display);
    usleep(100);
  }
  return 0;
}

static void Expose()
{
  XLockDisplay(display);
  if(!glXMakeCurrent(display, win, glxContext))
  {
    printf("glXMakeCurrent failed\n");
    exit(0);
  }
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  glColor3f(1.0, 0.0, 0.0);
  glRectf(-0.5, -0.5, 0.5, 0.5);
  swapBuffers();
  if(!glXMakeCurrent(display, 0, 0))
  {
    printf("glXMakeCurrent failed\n");
    exit(0);
  }
  XUnlockDisplay(display);
}
[/code]

--
Nickolay