AMD_DISABLE_SDMA for testing with -n12 (#14216)

test/test_jit.py

@@ -806,6 +806,7 @@ class TestJitGraphSplit(unittest.TestCase):
       multigraph=[self.ji_graph(6)],
       hcqgraph=[self.ji_graph(6)])
 
+  @unittest.skip("this fails if you don't have SDMA or are using AMD_DISABLE_SDMA=1")
   @unittest.skipIf(getenv("MOCKGPU"), "MockGPU does not support parallel copies")
   def test_jit_multidev_copy(self):
     if Device.DEFAULT in {"CPU"}: raise unittest.SkipTest("CPU/LLVM is not a valid default device for this test (zero-copies)")

tinygrad/runtime/ops_amd.py

@@ -1007,6 +1007,7 @@ class AMDDevice(HCQCompiled):
 
   @functools.lru_cache(None)
   def sdma_queue(self, idx:int):
+    if getenv("AMD_DISABLE_SDMA"): return None
     with contextlib.suppress(OSError): return self.create_queue(kfd.KFD_IOC_QUEUE_TYPE_SDMA, 0x200 if self.is_usb() else (16 << 20), idx=idx)
     return None