learning_gem5,configs: Update ruby_test

Use SimpleMemory instead of DDR3 so we can use the timing results in
tests. By using SimpleMemory, even if the DRAM timing changes the timing
of this test won't change. I expect the timing of SimpleMemory to never
change.

Change-Id: I4c75981d7b8bfc4dcca59e628e89f5a6ea4c0e36
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17871
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>

configs: Fix import path error in learning_gem5 part3

Change-Id: I2c5cd22bded998bae8e7aa77e42e1b042ce1c5f5
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17869
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>

configs: Use absolute import paths

Use absoluate import paths to be Python 3 compatible. This also
imports absolute_import from __future__ to ensure that Python 2.7
behaves the same way as Python 3.

Change-Id: Ica06ed95814e9cd3e768b3e1785075e36f6e56d0
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/16708
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

learning_gem5: Ruby random tester files for MSI

Adds a pair of scripts to run the Ruby random tester with the MSI protocol.

This code follows Learning gem5 Part 3.
http://learning.gem5.org/book/part3/index.html

Change-Id: I15550a36618546f0354163b0216cf771f434ed84
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/8944
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>