gpu-compute: Command processor read path from device

In full system mode, the AMDKernelCode object can reside in either the
system memory or in the dGPU device memory. Currently only reading from
the host/system memory is supported. This adds the necessary code to
read from the dGPU device memory.

Change-Id: I887fc706b3f9834db14e40f36fd29dd3d4602925
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57710
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed