util/tlm/README

This directory contains a demo of a coupling between gem5 and SystemC-TLM.
It is based on the gem5-systemc implementation in utils/systemc.
First a simple example with gem5's traffic generator is shown, later an full
system example.

Files:

    main.cc                -- demonstration top level
    sc_port.{cc,hh}        -- transactor that translates beween gem5 and tlm
    sc_mm.{cc,hh}          -- implementation of a tlm memory manager
    sc_ext.{cc,hh}         -- a TLM extension that carries the gem5 packet
    sc_target.{cc,hh}      -- an example TLM LT/AT memory module
    tlm.py                 -- simple gem5 configuration
    tgen.cfg               -- configuration file for the traceplayer

Other Files will be used from utils/systemc example:

    sc_logger.{cc,hh},
    sc_module.{cc,hh},
    sc_gem5_control.{cc,hh},
    stats.{cc,hh}


I. Traffic Generator Setup
==========================

To build:

First build a normal gem5 (cxx-config not needed, Python needed).
Second build gem5 as a library with cxx-config support and (optionally)
without python.

> cd ../..
> scons build/ARM/gem5.opt
> scons --with-cxx-config --without-python build/ARM/libgem5_opt.so
> cd util/tlm

Set a proper LD_LIBRARY_PATH e.g. for bash:
> export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/path/to/gem5/build/ARM/"

Then edit the Makefile to set the paths for SystemC and run make

> make

Make a config file for the C++-configured gem5 using normal gem5

> ../../build/ARM/gem5.opt ./tlm.py

The message "fatal: Can't find port handler type 'tlm'" is okay.
The configuration will be stored in the m5out/ directory

The binary 'gem5.opt.sc', that has been created in the make step,
can now be used to load in the generated config file from the previous
normal gem5 run.

Try:

> ./gem5.opt.sc m5out/config.ini -e 1000000

It should run a simulation for 1us.

To see more information what happens inside the TLM module use the -D flag:

> ./gem5.opt.sc m5out/config.ini -e 1000000 -D

To see more information about the port coupling use:

> ./gem5.opt.sc m5out/config.ini -e 1000000 -d ExternalPort

II. Full System Setup
=====================

Build gem5 as discribed in Section I. Then, make a config file for the
C++-configured gem5 using normal gem5

> ../../build/ARM/gem5.opt ../../configs/example/fs.py --tlm-memory=memory \
  --cpu-type=timing --num-cpu=1 --mem-type=SimpleMemory --mem-size=512MB   \
  --mem-channels=1  --caches --l2cache --machine-type=VExpress_EMM         \
  --dtb-filename=vexpress.aarch32.ll_20131205.0-gem5.1cpu.dtb              \
  --kernel=vmlinux.aarch32.ll_20131205.0-gem5                              \
  --disk-image=linux-aarch32-ael.img

The message "fatal: Can't find port handler type 'tlm'" is okay.
The configuration will be stored in the m5out/ directory

The binary 'gem5.opt.sc' can now be used to load in the generated config
file from the previous normal gem5 run.

Try:

> ./gem5.opt.sc m5out/config.ini -o 2147483648

The parameter -o specifies the begining of the memory region (0x80000000).
The system should boot now.

For conveniance a run_gem5.sh file holds all those commands


III. Elastic Trace Setup
========================

Elastic traces can also be replayed into the SystemC world.
For more information on elastic traces please refer to:

 - http://www.gem5.org/TraceCPU

 - Exploring System Performance using Elastic Traces:
   Fast, Accurate and Portable
   R. Jagtap, S. Diestelhorst, A. Hansson, M. Jung, N. Wehn.
   IEEE International Conference on Embedded Computer Systems Architectures
   Modeling and Simulation (SAMOS), July, 2016, Samos Island, Greece.

Similar to I. the simulation can be set up with this command:

> ../../build/ARM/gem5.opt ./tlm_elastic.py

Then:

> ./gem5.opt.sc m5out/config.ini