Add env var to toggle large bar support in runtime

Use ROC_ENABLE_LARGE_BAR (0/1) to toggle. The support is
enabled by default.

Change-Id: I6cb93a46594cb6f5e90bf6057738330225efb553


[ROCm/clr commit: d10d691e76]

projects/clr/rocclr/device/rocm/rocdevice.cpp

@@ -896,7 +896,7 @@ hsa_status_t Device::iterateGpuMemoryPoolCallback(hsa_amd_memory_pool_t pool, vo
           if (tmp == HSA_AMD_MEMORY_POOL_ACCESS_NEVER_ALLOWED) {
             dev->info_.largeBar_ = false;
           } else {
-            dev->info_.largeBar_ = true;
+            dev->info_.largeBar_ = ROC_ENABLE_LARGE_BAR;
           }
         }
 

projects/clr/rocclr/utils/flags.hpp

@@ -72,8 +72,6 @@ release(bool, GPU_FLUSH_ON_EXECUTION, false,                                  \
         "Submit commands to HW on every operation. 0 - Disable, 1 - Enable")  \
 release(bool, GPU_USE_SYNC_OBJECTS, true,                                     \
         "If enabled, use sync objects instead of polling")                    \
-release(size_t, GPU_FORCE_BLIT_COPY_SIZE, 0,                                  \
-        "Size in KB of the threshold below which to force blit instead for sdma") \
 release(bool, CL_KHR_FP64, true,                                              \
         "Enable/Disable support for double precision")                        \
 release(cstring, AMD_OCL_BUILD_OPTIONS, 0,                                    \
@@ -233,7 +231,11 @@ release(uint, AMD_OPT_FLUSH, 1,                                               \
         "0x1 = Use device-scope fence operations when possible.")             \
 release(uint, HIP_HIDDEN_FREE_MEM, 0,                                         \
         "Reserve free mem reporting in Mb"                                    \
-        "0 = Disable")
+        "0 = Disable")                                                        \
+release(size_t, GPU_FORCE_BLIT_COPY_SIZE, 0,                                  \
+        "Size in KB of the threshold below which to force blit instead for sdma") \
+release(bool, ROC_ENABLE_LARGE_BAR, true,                                     \
+        "Enable Large Bar if supported by the device")
 
 namespace amd {