gpu-compute: Fatal on dynamic scratch allocation in GPUFS

This is known not working in GPUFS. As a result, the simulation will
never end. Rather than simulate forever, add a fatal for now to exit
simulation until support for this functionality is added.

Change-Id: I8e45996a7eb781575e8643baea05daf87bc5f1c3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/58472
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/gpu-compute/gpu_command_processor.hh

@@ -57,6 +57,7 @@
 #include "gpu-compute/gpu_compute_driver.hh"
 #include "gpu-compute/hsa_queue_entry.hh"
 #include "params/GPUCommandProcessor.hh"
+#include "sim/full_system.hh"
 
 namespace gem5
 {
@@ -219,6 +220,10 @@ class GPUCommandProcessor : public DmaVirtDevice
                     task->amdQueue.compute_tmpring_size_wavesize * 1024,
                     task->privMemPerItem());
 
+            // Currently this is not supported in GPU full system
+            fatal_if(FullSystem,
+                     "Runtime dynamic scratch allocation not supported");
+
             updateHsaSignal(task->amdQueue.queue_inactive_signal.handle, 1,
                             [ = ] (const uint64_t &dma_buffer)
                                 { WaitScratchDmaEvent(task, dma_buffer); });