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OpenCL

maxis11
Adept I
Adept I

XCloseDisplay and clGetPlatformIDs

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i catch segmentation fault in


XCloseDisplay(display);


If before it i call


clGetPlatformIDs(0, NULL, &numPlatforms);


I'm doing something wrong, or it's a bug?

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himanshu_gautam
Grandmaster
Grandmaster

Re: XCloseDisplay and clGetPlatformIDs

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I can reproduce the issue. GL and CL and behaving weird together. Forwarding it to engineering team.

But can you tell what is the motive behind adding an OpenCL API, in the purely graphics program. Are you trying to do CL_GL interop finally?

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himanshu_gautam
Grandmaster
Grandmaster

Re: XCloseDisplay and clGetPlatformIDs

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Can you provide a small test-code. I am not very familiar with xcloseDisplay().

Also provide your GPU, CPU, Driver,OS, and SDK version.

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maxis11
Adept I
Adept I

Re: XCloseDisplay and clGetPlatformIDs

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Example:

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <X11/X.h>

#include <X11/Xlib.h>

#include <X11/Xutil.h>

#include <GL/gl.h>

#include <GL/glx.h>

#include <CL/cl.h>

#include <CL/cl_gl.h>

#define GLX_CONTEXT_MAJOR_VERSION_ARB       0x2091

#define GLX_CONTEXT_MINOR_VERSION_ARB       0x2092

typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);

static bool isExtensionSupported(const char *extList, const char *extension)

{

  const char *start;

  const char *where, *terminator;

  where = strchr(extension, ' ');

  if ( where || *extension == '\0' )

    return false;

  for ( start = extList; ; ) {

    where = strstr( start, extension );

    if ( !where )

      break;

    terminator = where + strlen( extension );

    if ( where == start || *(where - 1) == ' ' )

      if ( *terminator == ' ' || *terminator == '\0' )

        return true;

    start = terminator;

  }

  return false;

}

static bool ctxErrorOccurred = false;

static int ctxErrorHandler( Display *dpy, XErrorEvent *ev )

{

    ctxErrorOccurred = true;

    return 0;

}

int main (int argc, char ** argv)

{

  Display *display = XOpenDisplay(0);

  if ( !display )

  {

    printf( "Failed to open X display\n" );

    exit(1);

  }

  static int visual_attribs[] =

    {

      GLX_X_RENDERABLE    , True,

      GLX_DRAWABLE_TYPE   , GLX_WINDOW_BIT,

      GLX_RENDER_TYPE     , GLX_RGBA_BIT,

      GLX_X_VISUAL_TYPE   , GLX_TRUE_COLOR,

      GLX_RED_SIZE        , 8,

      GLX_GREEN_SIZE      , 8,

      GLX_BLUE_SIZE       , 8,

      GLX_ALPHA_SIZE      , 8,

      GLX_DEPTH_SIZE      , 24,

      GLX_STENCIL_SIZE    , 8,

      GLX_DOUBLEBUFFER    , True,

      None

    };

  int glx_major, glx_minor;

  if ( !glXQueryVersion( display, &glx_major, &glx_minor ) ||

       ( ( glx_major == 1 ) && ( glx_minor < 3 ) ) || ( glx_major < 1 ) )

  {

    printf( "Invalid GLX version" );

    exit(1);

  }

  printf( "Getting matching framebuffer configs\n" );

  int fbcount;

  GLXFBConfig *fbc = glXChooseFBConfig( display, DefaultScreen( display ), visual_attribs, &fbcount );

  if ( !fbc )

  {

    printf( "Failed to retrieve a framebuffer config\n" );

    exit(1);

  }

  printf( "Found %d matching FB configs.\n", fbcount );

  printf( "Getting XVisualInfos\n" );

  int best_fbc = -1, worst_fbc = -1, best_num_samp = -1, worst_num_samp = 999;

  int i;

  for ( i = 0; i < fbcount; i++ )

  {

    XVisualInfo *vi = glXGetVisualFromFBConfig( display, fbc );

    if ( vi )

    {

      int samp_buf, samples;

      glXGetFBConfigAttrib( display, fbc, GLX_SAMPLE_BUFFERS, &samp_buf );

      glXGetFBConfigAttrib( display, fbc, GLX_SAMPLES       , &samples  );

      if ( best_fbc < 0 || samp_buf && samples > best_num_samp )

        best_fbc = i, best_num_samp = samples;

      if ( worst_fbc < 0 || !samp_buf || samples < worst_num_samp )

        worst_fbc = i, worst_num_samp = samples;

    }

    XFree( vi );

  }

  GLXFBConfig bestFbc = fbc[ best_fbc ];

  XFree( fbc );

  XVisualInfo *vi = glXGetVisualFromFBConfig( display, bestFbc );

  printf( "Creating colormap\n" );

  XSetWindowAttributes swa;

  Colormap cmap;

  swa.colormap = cmap = XCreateColormap( display,

                                         RootWindow( display, vi->screen ),

                                         vi->visual, AllocNone );

  swa.background_pixmap = None ;

  swa.border_pixel      = 0;

  swa.event_mask        = StructureNotifyMask;

  printf( "Creating window\n" );

  Window win = XCreateWindow( display, RootWindow( display, vi->screen ),

                              0, 0, 800, 640, 0, vi->depth, InputOutput,

                              vi->visual,

                              CWBorderPixel|CWColormap|CWEventMask, &swa );

  if ( !win )

  {

    printf( "Failed to create window.\n" );

    exit(1);

  }

  XFree( vi );

  XStoreName( display, win, "GL 4.2 Window" );

  printf( "Mapping window\n" );

  XMapWindow( display, win );

  const char *glxExts = glXQueryExtensionsString( display,DefaultScreen( display ) );

  glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;

  glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB( (const GLubyte *) "glXCreateContextAttribsARB" );

  GLXContext ctx = 0;

  ctxErrorOccurred = false;

  int (*oldHandler)(Display*, XErrorEvent*) =

      XSetErrorHandler(&ctxErrorHandler);

  if ( !isExtensionSupported( glxExts, "GLX_ARB_create_context" ) ||

       !glXCreateContextAttribsARB )

  {

    printf( "glXCreateContextAttribsARB() not found"

            " ... using old-style GLX context\n" );

    ctx = glXCreateNewContext( display, bestFbc, GLX_RGBA_TYPE, 0, True );

  }

  else

  {

    int context_attribs[] =

      {

        GLX_CONTEXT_MAJOR_VERSION_ARB, 4,

        GLX_CONTEXT_MINOR_VERSION_ARB, 2,

        None

      };

    printf( "Creating context\n" );

    ctx = glXCreateContextAttribsARB( display, bestFbc, 0, True, context_attribs );

    XSync( display, False );

    if ( !ctxErrorOccurred && ctx )

      printf( "Created GL 4.2 context\n" );

    else

    {

      context_attribs[1] = 1;

      context_attribs[3] = 0;

      ctxErrorOccurred = false;

      printf( "Failed to create GL 4.2 context"

              " ... using old-style GLX context\n" );

      ctx = glXCreateContextAttribsARB( display, bestFbc, 0,

                                        True, context_attribs );

    }

  }

  XSync( display, False );

  XSetErrorHandler( oldHandler );

  if ( ctxErrorOccurred || !ctx )

  {

    printf( "Failed to create an OpenGL context\n" );

    exit(1);

  }

  if ( ! glXIsDirect ( display, ctx ) )

  {

    printf( "Indirect GLX rendering context obtained\n" );

  }

  else

  {

    printf( "Direct GLX rendering context obtained\n" );

  }

  printf( "Making context current\n" );

  glXMakeCurrent( display, win, ctx );

  cl_int err;

  cl_uint numPlatforms;

  err=clGetPlatformIDs(0, NULL, &numPlatforms); //error here

  if (err!=CL_SUCCESS)

  {

  XDestroyWindow( display, win );

  XFreeColormap( display, cmap );

  XCloseDisplay( display );

  exit (1);

  }

  glClearColor ( 0, 0.5, 1, 1 );

  glClear ( GL_COLOR_BUFFER_BIT );

  glXSwapBuffers ( display, win );

  sleep( 1 );

  glClearColor ( 1, 0.5, 0, 1 );

  glClear ( GL_COLOR_BUFFER_BIT );

  glXSwapBuffers ( display, win );

  sleep( 1 );

  glXMakeCurrent( display, 0, 0 );

  glXDestroyContext( display, ctx );

  XDestroyWindow( display, win );

  XFreeColormap( display, cmap );

  XCloseDisplay( display );

  return 0;

}

libs : -lX11 -lGL -lOpenCL

CPU: A4

GPU: HD 6480G + 7470M

Catalyst : 13.6

OS: Ubuntu 13.04

APP SDK: 2.8

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himanshu_gautam
Grandmaster
Grandmaster

Re: XCloseDisplay and clGetPlatformIDs

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I can reproduce the issue. GL and CL and behaving weird together. Forwarding it to engineering team.

But can you tell what is the motive behind adding an OpenCL API, in the purely graphics program. Are you trying to do CL_GL interop finally?

View solution in original post

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maxis11
Adept I
Adept I

Re: XCloseDisplay and clGetPlatformIDs

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I'm making game engine and this code is only example of the bug, in real situation i'm using CL_GL interop + glfw. By the way, if we call clGetPlatformIDs before X code, program will run normally.