[Libre-soc-dev] Running the libre-soc CPU under cxxsim

[Cesar Strauss]

Em 19/09/2020 18:58, Luke Kenneth Casson Leighton escreveu:
> On Sat, Sep 19, 2020 at 10:41 PM Cesar Strauss <cestrauss at gmail.com> wrote:
> 
>> Note that "nmigen.sim.pysim" and "nmigen.sim.cxxsim" were never present
>> in a released nMigen version, so the change in API, in the middle of a
>> development cycle, is warranted.
> 
> ok so we need a big patch to get up-to-date, first.  i am holding
> back, not updating nmigen master regularly in case it introduces bugs
> (like it did 2 months ago).
> 
>>> really this should be an environment variable
>>>
>>> import os
>>>       sim = Simulator(m, engine=os.environ.get('NMIGEN_SIM_MODE"))
>>>
>>
>> This is exactly the way that the simulator API now works.
> 
> excellent.
> 

Per discussion above, found a way to conditionally switch to cxxsim,
without losing backwards compatibility with earlier nMigen git versions.

Applied to src/soc/experiment/alu_fsm.py, as an example.

https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=70cee4d6e7d454c5378b455dd8a2779dbd82adcd

commit 70cee4d6e7d454c5378b455dd8a2779dbd82adcd (HEAD -> master,
origin/master, origin/HEAD)
Author: Cesar Strauss <cestrauss at gmail.com>
Date:   Mon Sep 21 08:47:13 2020 -0300

    Port soc.experiment.alu_fsm to the new way of invoking cxxsim

    To use cxxsim, export NMIGEN_SIM_MODE=cxxsim from the shell.
    Be sure to check out the cxxsim branch of nMigen, and update yosys
    to the latest commit as well.

    To use pysim, just keep NMIGEN_SIM_MODE unset. This should be
    backwards compatible to old developer versions of nMigen.

    Alternatively, when using a recent developer version,
    export NMIGEN_SIM_MODE=pysim.