configs,mem-ruby: CHI-based Ruby protocol

This patch add a new Ruby cache coherence protocol based on Arm' AMBA5
CHI specification. The CHI protocol defines and implements two state
machine types:

- Cache_Controller: generic cache controller that can be configured as:
    - Top-level L1 I/D cache
    - A intermediate level (L2, L3, ...) private or shared cache
    - A CHI home node (i.e. the point of coherence of the system and
        has the global directory)
    - A DMA requester

- Memory_Controller: implements a CHI slave node and interfaces with
    gem5 memory controller. This controller has the functionality of a
    Directory_Controller on the other Ruby protocols, except it doesn't
    have a directory.

The Cache_Controller has multiple cache allocation/deallocation
parameters to control the clusivity with respect to upstream caches.
Allocation can be completely disabled to use Cache_Controller as a
DMA requester or as a home node without a shared LLC.

The standard configuration file configs/ruby/ provides a
'create_system' compatible with configs/example/ and
configs/example/ and creates a system with private L1/L2 caches
per core and a shared LLC at the home nodes. Different cache topologies
can be defined by modifying 'create_system' or by creating custom
scripts using the structures defined in configs/ruby/

This patch also includes the 'CustomMesh' topology script to be used
with CHI. CustomMesh generates a 2D mesh topology with the placement
of components manually defined in a separate configuration file using
the --noc-config parameter.
The example in configs/example/noc_config/2x4.yaml creates a simple 2x4
mesh. For example, to run a SE mode simulation, with 4 cores,
4 mem ctnrls, and 4 home nodes (L3 caches):

build/ARM/gem5.opt configs/example/ \
--cmd 'tests/test-progs/hello/bin/arm/linux/hello' \
--ruby --num-cpus=4 --num-dirs=4 --num-l3caches=4 \
--topology=CustomMesh --noc-config=configs/example/noc_config/2x4.yaml

If one doesn't care about the component placement on the interconnect,
the 'Crossbar' and 'Pt2Pt' may be used and they do not require the
--noc-config option.

Additional authors:
    Joshua Randall <>
    Pedro Benedicte <>
    Tuan Ta <>


Change-Id: I856524b0afd30842194190f5bd69e7e6ded906b0
Signed-off-by: Tiago Mück <>
Reviewed-by: Jason Lowe-Power <>
Maintainer: Jason Lowe-Power <>
Tested-by: kokoro <>
16 files changed