Add an utility class that provides a service for another process
query and get the fd of the corresponding region in gem5's physmem.
Basically, the service works in this way:
1. client connect to the unix socket created by a SharedMemoryServer
2. client send a request {start, end} to gem5
3. the server locates the corresponding shared memory
4. gem5 response {offset} and pass {fd} in ancillary data
mmap fd at offset will provide the client the view into the physical
memory of the request range.
Change-Id: I9d42fd8a41fc28dcfebb45dec10bc9ebb8e21d11
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57729
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Tested-by: kokoro <noreply+kokoro@google.com>
