[Beignet] [PATCH] Fail gracefully on unsupported hardware

[Rebecca Palmer]

If no compatible hardware is present, clGetDeviceIDs is supposed to 
report CL_DEVICE_NOT_FOUND to the caller, but in Beignet this currently
ends the whole program with exit(-1) or assert(0).  This fixes this.

This is required to have a "just works" OpenCL in Debian/Ubuntu, as
their package manager doesn't know the hardware and hence commonly will
install Beignet on hardware that doesn't support it; returning an error
allows the caller to try other ICDs until it finds the right one, or to
run without using OpenCL.  Previous discussion:
http://lists.alioth.debian.org/pipermail/pkg-opencl-devel/Week-of-Mon-20140217/000096.html
http://lists.alioth.debian.org/pipermail/pkg-opencl-devel/Week-of-Mon-20140217/000100.html

Testing if you only have supported hardware: use a chroot, the GPU
isn't visible from inside.  

Identical patch in case line wrap mangles this:
https://bugs.debian.org/cgi-bin/bugreport.cgi?msg=27;filename=fail_gracefully_without_hardware;att=1;bug=745363

Signed-off-by: Rebecca Palmer <rebecca_palmer at zoho.com>

--- beignet-0.9.3git.orig/src/cl_api.c
+++ beignet-0.9.3git/src/cl_api.c
@@ -170,6 +170,7 @@ cl_check_device_type(cl_device_type devi
 static cl_int
 cl_device_id_is_ok(const cl_device_id device)
 {
+  if(UNLIKELY(device == NULL)) return CL_FALSE;
   return device != cl_get_gt_device() ? CL_FALSE : CL_TRUE;
 }
 
--- beignet-0.9.3git.orig/src/cl_device_data.h
+++ beignet-0.9.3git/src/cl_device_data.h
@@ -20,6 +20,8 @@
 #ifndef __CL_DEVICE_DATA_H__
 #define __CL_DEVICE_DATA_H__
 
+#define INVALID_CHIP_ID -1 //returned by intel_get_device_id if no device found
+
 #define PCI_CHIP_GM45_GM                0x2A42
 #define PCI_CHIP_IGD_E_G                0x2E02
 #define PCI_CHIP_Q45_G                  0x2E12
--- beignet-0.9.3git.orig/src/intel/intel_driver.c
+++ beignet-0.9.3git/src/intel/intel_driver.c
@@ -193,7 +193,7 @@ intel_driver_init(intel_driver_t *driver
 #endif /* EMULATE_GEN */
 }
 
-static void
+static cl_int
 intel_driver_open(intel_driver_t *intel, cl_context_prop props)
 {
   int cardi;
@@ -203,7 +203,7 @@ intel_driver_open(intel_driver_t *intel,
       && props->gl_type != CL_GL_GLX_DISPLAY
       && props->gl_type != CL_GL_EGL_DISPLAY) {
     fprintf(stderr, "Unsupported gl share type %d.\n", props->gl_type);
-    exit(-1);
+    return CL_INVALID_OPERATION;
   }
 
   intel->x11_display = XOpenDisplay(NULL);
@@ -239,7 +239,7 @@ intel_driver_open(intel_driver_t *intel,
 
   if(!intel_driver_is_active(intel)) {
     fprintf(stderr, "Device open failed, aborting...\n");
-    exit(-1);
+    return CL_DEVICE_NOT_FOUND;
   }
 
 #ifdef HAS_EGL
@@ -247,6 +247,7 @@ intel_driver_open(intel_driver_t *intel,
     assert(props->egl_display);
   }
 #endif
+  return CL_SUCCESS;
 }
 
 static void
@@ -399,7 +400,7 @@ intel_get_device_id(void)
 
   driver = intel_driver_new();
   assert(driver != NULL);
-  intel_driver_open(driver, NULL);
+  if(UNLIKELY(intel_driver_open(driver, NULL) != CL_SUCCESS)) return INVALID_CHIP_ID;
   intel_device_id = driver->device_id;
   intel_driver_context_destroy(driver);
   intel_driver_close(driver);
@@ -426,7 +427,7 @@ cl_intel_driver_new(cl_context_prop prop
 {
   intel_driver_t *driver = NULL;
   TRY_ALLOC_NO_ERR (driver, intel_driver_new());
-  intel_driver_open(driver, props);
+  if(UNLIKELY(intel_driver_open(driver, props) != CL_SUCCESS)) goto error;
 exit:
   return driver;
 error:
--- beignet-0.9.3git.orig/src/intel/intel_gpgpu.c
+++ beignet-0.9.3git/src/intel/intel_gpgpu.c
@@ -1500,6 +1500,4 @@ intel_set_gpgpu_callbacks(int device_id)
     intel_gpgpu_get_scratch_index = intel_gpgpu_get_scratch_index_gen7;
     intel_gpgpu_post_action = intel_gpgpu_post_action_gen7;
   }
-  else
-    assert(0);
 }