+[[!toc ]]
+
+---
+
# HDL workflow
This section describes the workflow and some best practices for developing
-the Libre-SoC hardware. We use nmigen, yosys and symbiyosys, and this
+the Libre-SOC hardware. We use nmigen, yosys and symbiyosys, and this
page is intended not just to help you get set up, it is intended to
help advise you of some tricks and practices that will help you become
effective team contributors.
and formal mathematical proofs for all code at all levels is therefore
paramount.
+Therefore, we need not only to be "self-sufficient" (absolutely
+under no circumstances critically reliant on somebody else's servers
+**or protocols**) we also need to ensure that everything (including
+all communication such as the mailing list archives) are recorded,
+replicable, and accessible in perpetuity. Use of slack or a "forum"
+either actively prevents or makes that much harder.
+
# Collaboration resources
+The main message here: **use the right tool for the right job**.
+
+* mailing list: general communication and discussion.
+* irc channel #libre-soc on irc.libera.chat: real(ish)-time communication.
+* bugtracker: task-orientated, goal-orientated *focussed* discussion.
+* ikiwiki: document store, information store, and (editable) main website
+* git repositories: code stores (**not binary or auto-generated output store**)
+* ftp server (<https://ftp.libre-soc.org/>): large (temporary,
+ auto-generated) file store.
+
+Note also the lack of a "forum" in the above list. this is very
+deliberate. forums are a serious distraction when it comes to technical
+heavily goal-orientated development. recent internet users may enjoy
+looking up the "AOL metoo postings" meme.
+
+Note also the complete lack of "social platforms". if we wanted to tell
+everybody how much better each of us are than anyone else in the team,
+how many times we made a commit (look at me, look at me, i'm so clever),
+and how many times we went to the bathroom, we would have installed a
+social media based project "management" system.
+
## Main contact method: mailing list
To respect the transparency requirements, conversations need to be
public and archived (i.e not skype, not telegram, not discord,
and anyone seriously suggesting slack will be thrown to the
lions). Therefore we have a mailing list. Everything goes through
-there. <http://lists.libre-riscv.org/mailman/listinfo/libre-riscv-dev>
+there. <https://lists.libre-soc.org/mailman/listinfo/libre-soc-dev>
therefore please do google "mailing list etiquette" and at the very
minimum look up and understand the following:
using phone at airport flight soon, v. quick reply: ....")
* Always trim context but do not cut excessively to the point where people
cannot follow the discussion. Especially do not cut the attribution
- ("On monday xxx wrote")
+ ("On monday xxx wrote") of something that you are actually replying
+ to.
* Use inline replies i.e. reply at the point in the relevant part of
the conversation, as if you were actually having a conversation.
* Follow standard IETF reply formatting, using ">" for cascaded
the link. Which should not require any kind of login to access. ask the
listadmin if you don't have anywhere suitable: FTP access can be arranged.
+### Actionable items from mailing list
+
If discussions result in any actionable items, it is important not to
lose track of them. Create a bugreport, find the discussion in the
-archives <http://lists.libre-riscv.org/pipermail/libre-riscv-dev/>,
+archives <https://lists.libre-soc.org/pipermail/libre-soc-dev/>,
and put the link actually in the bugtracker as one of the comments.
-At some point it may become better to use <http://bugs.libre-riscv.org>
+At some point in any discussion, the sudden realisation may dawn on one
+or more people that this is an "actionable" discussion. at that point
+it may become better to use <https://bugs.libre-soc.org/>
itself to continue the discussion rather than to keep on dropping copies
of links into the bugtracker. The bugtracker sends copies of comments
*to* the list however this is 'one-way' (note from lkcl: because this
involves running an automated perl script from email, on every email,
on the server, that is a high security risk, and i'm not doing it. sorry.)
+### Mailing list != editable document store
+
Also, please do not use the mailing list as an "information or document
-store or poor-man's editor". We have the wiki for that. Edit a page and
+store or poor-man's editor" **including not sending large images**.
+We have the wiki for that. Edit a page and
tell people what you did (summarise rather than drop the entire contents
at the list) and include the link to the page.
Or, if it is more appropriate, commit a document (or source code)
into the relevant git repository then look up the link in the gitweb
source tree browser and post that (in the bugtracker or mailing list)
-See <http://git.libre-riscv.org>
+See <https://git.libre-soc.org/>
+
+### gmail "spam"ifying the list
+
+See <https://blog.kittycooper.com/2014/05/keeping-my-mailing-list-emails-out-of-gmails-spam-folder/>
+
+Basically it is possible to select any message from the list, create a
+"filter" (under "More"), and, on the 2nd dialog box, click the "never
+send this to Spam" option.
## Bugtracker
## ikiwiki
-Runs the main libre-riscv.org site (including this page). effective,
+Runs the main libre-soc.org site (including this page). effective,
stunningly light on resources, and uses a git repository not a database.
That means it can be edited offline.
Hint: to create a new page, find a suitable page that would link to it,
first, then put the link in of the page you want to create, as if the
-page already exists. Save that page, and you will find a questionmark
+page already exists. Save that page, and you will find a question mark
next to the new link you created. click that link, and it will fire up a
"create new page" editor.
+Wiki pages are formatted in [[markdown|ikiwiki/markdown]] syntax.
+
Hint again: the wiki is backed by a git repository. Don't go overboard
but at the same time do not be afraid that you might "damage" or "lose"
pages. Although it would be a minor pain, the pages can always be
## git
-we use git. more on this below. we also use gitolite3 running on a
-dedicated server. again, it is extremely effective and low resource
-utilisation. reminder: lions are involved if github is mentioned.
+We use git. More on this below. We also use
+[gitolite3](https://gitolite.com/gitolite/) running on a dedicated server.
+again, it is extremely effective and low resource utilisation. Reminder:
+lions are involved if github is mentioned.
+
+[gitweb](https://git.wiki.kernel.org/index.php/Gitweb) is provided which
+does a decent job. <https://git.libre-soc.org/>
+
+[Git](https://en.wikipedia.org/wiki/Git) does version control, ie it
+tracks changes to files so that previous versions can be got back or
+compared.
+
+Checklist page [[HDL_workflow/git_checklist]]
+
+## ftp server
+
+<https://ftp.libre-soc.org/> is available for storing large files
+that do not belong in a git repository, if we have (or ever need)
+any. Images (etc.) if small and appropriate should go into the
+wiki, however .tgz archives (etc.) and, at some point, binaries,
+should be on the ftp server.
-gitweb is provided which does a decent job. <http://git.libre-riscv.org>
+Ask on the list if you have a file that belongs on the ftp server.
## server
-as an aside: all this is "old school" and run on a single core 512MB
+As an aside: all this is "old school" and run on a single core 512MB
VM with only a 20GB HDD allocation. it costs only 8 GBP per month from
mythic-beasts and means that the project is in no way dependent on anyone
else - not microsoft, not google, not facebook, not amazon.
-we tried gitlab. it didn't go well.
+We tried [gitlab](https://about.gitlab.com/). it didn't go well. please
+don't ask to replace the above extremely resource-efficient services
+with it.
# Hardware
What is particularly useful is to have hi-res screens (curved is
*strongly* recommended if the LCD is over 24in wide, to avoid eyeballs
-going "prism" through longterm use), and to have several of them: the
+going "prism" through long term use), and to have several of them: the
more the better. Either a DisplayLink UD160A (or more modern variant)
or simply using a second machine (lower spec hardware because it will
run editors) is really effective.
# Operating System
-First install and become familiar with Debian (ubuntu if you absolutely
+First install and become familiar with
+[Debian](https://www.debian.org/) ([Ubuntu](https://ubuntu.com/)
+if you absolutely
must) for standardisation cross-team and so that toolchain installation
is greatly simplified. yosys in particular warns that trying to use
Windows, BSD or MacOS will get you into a world of pain.
# editors and editing
Whilst this is often a personal choice, the fact that many editors are
-GUI based and run fullscreen with the entire right hand side *and* middle
+GUI based and run full-screen with the entire right hand side *and* middle
*and* the majority of the left side of the hi-res screen entirely unused
and bereft of text leaves experienced developers both amused and puzzled.
-At the point where such fullscreen users commit code with line lengths
+At the point where such full-screen users commit code with line lengths
well over 160 characters, that amusement quickly evaporates.
-Where the problems occur with fullscreen editor usage is when a project
+Where the problems occur with full-screen editor usage is when a project
is split into dozens if not hundreds of small files (as this one is). At
that point it becomes pretty much essential to have as many as six to
eight files open *and on-screen* at once, without overlaps i.e. not in
[[!img 2020-01-24_11-56.png size=640x ]]
(hint/tip: fvwm2 set up with "mouse-over to raise focus, rather than
-additionally requiring a mouseclick, can save a huge amount of cumulative
+additionally requiring a mouse click, can save a huge amount of cumulative
development time here, switching between editor terminal(s) and the
command terminals).
Once this becomes necessary, it it turn implies that having greater
-than 80 chars per line - and running editors fullscreen - is a severe
-hindance to an essential *and highly effective* workflow technique.
+than 80 chars per line - and running editors full-screen - is a severe
+hinderance to an essential *and highly effective* workflow technique.
Additionally, care should be taken to respect that not everyone will have
200+ column editor windows and the eyesight of a hawk. They may only have
continuously page-up and page-down to read the code even of a single
function, in full.
-This helps explain in part, below, why compliance with pep8 is enforced,
-including its 80 character limit. In short: not everyone has the same
-"modern" GUI workflow or has access to the same computing resources as
-you, so please do respect that.
+This helps explain in part, below, why compliance with
+[pep8](https://pep8.org/) is enforced, including its 80 character limit.
+In short: not everyone has the same "modern" GUI workflow or has access
+to the same computing resources as you, so please do respect that.
-# Software prerequisites
+More on this concept is
+[here](https://www.linuxjournal.com/content/line-length-limits).
+Note *very pointedly* that Linus Torvalds *specifically* states that
+he does not want Linux kernel development to become the exclusive
+domain of the "wealthy". That means **no** to assumptions about
+access to ultra-high resolution screens.
-Whilst many resources online advocate "sudo" in front of all root-level
-commands below, this quickly becomes tiresome. run "sudo bash", get a
+# Software prerequisites<a name="software-prerequisites"></a>
+
+**Please make sure if you install manually that you install dependencies
+in strict order. Failing to adhere to this will result in pip3 downloading
+unauthorised older software versions. See
+<http://lists.libre-soc.org/pipermail/libre-soc-dev/2021-September/003666.html>**
+
+Whilst many resources online advocate "`sudo`" in front of all root-level
+commands below, this quickly becomes tiresome. run "`sudo bash`", get a
root prompt, and save yourself some typing.
* sudo bash
* apt-get install vim exuberant-ctags
* apt-get install build-essential
-* apt-get install git python3.7 python3.7-dev python-nosetest3
+* apt-get install git python3.7 python3.7-dev python3-nose
* apt-get install graphviz xdot gtkwave
+* apt-get install python3-venv
+* apt-get install python-virtualenv # this is an alternative to python3-venv
+* apt-get install tcl-dev libreadline-dev bison flex libffi-dev iverilog
* return to user prompt (ctrl-d)
-This will get you python3 and other tools that are needed. graphviz is
-essential for showing the interconnections between cells, and gtkwave
-is essential for debugging.
+(The above assumes that you are running Debian.)
+
+This will get you python3 and other tools that are
+needed. [graphviz](https://graphviz.org/) is essential
+for showing the interconnections between cells, and
+[gtkwave](http://gtkwave.sourceforge.net/) is essential for debugging.
+
+If you would like to save yourself a lot more typing, check out the
+[dev-env-setup](https://git.libre-soc.org/?p=dev-env-setup.git;a=summary)
+repository, examine the scripts there and use them to automate much of
+the process below.
+
+If you would like just to install only the apt dependencies use
+[install-hdl-apt-reqs](https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=install-hdl-apt-reqs;hb=HEAD) instead.
+
+This page gives more details and a step by step process : [[HDL_workflow/devscripts]]
## git
get "lost" or isolated and out of touch due to major branch diversion,
and that people communicate and coordinate with each other.
+This is not a hard rule: under special cirmstances branches can be useful.
+They should not however be considered "routine".
+
## yosys
-Follow the source code (git clone) instructions here:
+Follow the source code (git clone) instructions here, do **not** use
+the "stable" version (do not download the tarball):
<http://www.clifford.at/yosys/download.html>
-Do not try to use a fixed revision (currently 0.9), nmigen is evolving
-and frequently interacts with yosys
+Or, alternatively, use the
+[hdl-tools-yosys](https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=hdl-tools-yosys;hb=HEAD)
+script (which also installs symbiyosys and its dependencies)
+
+Do not try to use a fixed revision of yosys (currently 0.9), nmigen is
+evolving and frequently interacts with yosys.
+
+[Yosys](http://www.clifford.at/yosys/) is a framework for Verilog RTL.
+[Verilog](https://en.wikipedia.org/wiki/Verilog) is a hardware description
+language.
+RTL [Register Transfer
+Level](https://en.wikipedia.org/wiki/Register-transfer_level)
+models how data moves between
+[registers](https://en.wikipedia.org/wiki/Hardware_register).
## symbiyosys
-Follow the instructions here:
-<https://symbiyosys.readthedocs.io/en/latest/quickstart.html#installing>
+To install follow the [instructions
+here](https://symbiyosys.readthedocs.io/en/latest/install.html)
+Once done look at [A simple BMC
+example](https://symbiyosys.readthedocs.io/en/latest/quickstart.html)
You do not have to install all of those (avy, boolector can be left
out if desired) however the more that are installed the more effective
the formal proof scripts will be (less resource utilisation in certain
circumstances).
+[SymbiYosys](https://symbiyosys.readthedocs.io/en/latest/) (sby) is a
+front-end driver program for Yosys-based formal hardware verification
+flows.
+
## nmigen
-nmigen may be installed as follows:
+**PLEASE NOTE: it is critical to install nmigen as the first dependency
+prior to installing any further python-based Libre-SOC HDL repositories.
+If "pip3 list" shows that nmigen has been auto-installed please remove it**
+
+[nmigen](https://nmigen.info/) may be installed as follows:
* mkdir ~/src
* cd !$
-* git clone https://github.com/m-labs/nmigen.git
+* git clone https://github.com/nmigen/nmigen.git
* cd nmigen
* sudo bash
* python3 setup.py develop
* ctrl-d
-testing can then be carried out with "python3 setup.py test"
+Testing can then be carried out with "python3 setup.py test"
+
+nmigen is a Python toolbox for building complex digital hardware.
## Softfloat and sfpy
-These are a test suite dependency for the ieee754fpu library, and
-will be changed in the future to use Jacob's algorithmic numeric
-library. In the meantime, sfpy can be built as follows:
+These are a test suite dependency for the
+[ieee754fpu](https://www.gaisler.com/index.php/products/ipcores/ieee754fpu)
+library, and will be changed in the future to use Jacob's
+[simple-soft-float](https://crates.io/crates/simple-soft-float) library.
+In the meantime, sfpy can be built as follows:
git clone --recursive https://github.com/billzorn/sfpy.git
cd sfpy
git apply /path/to/ieee754fpu/berkeley-softfloat.patch
cd ..
- # install dependencies
+ # prepare a virtual environment for building
python3 -m venv .env
- . .env/bin/activate
+
+ # or, if you prefer the old way:
+ # virtualenv -p python3 .env
+
+ # install dependencies
+ source .env/bin/activate
pip3 install --upgrade -r requirements.txt
# build
- make lib -j8
+ make lib -j$(nproc)
make cython
- make inplace -j8
+ make inplace -j$(nproc)
make wheel
# install
You can test your installation by doing the following:
python3
- >>> from sfpy import *
+ >>> from sfpy import Posit8
>>> Posit8(1.3)
It should print out `Posit8(1.3125)`
+## qemu, cross-compilers, gdb
+
+As we are doing POWER ISA, POWER ISA compilers, toolchains and
+emulators are required.
+Again, if you want to save yourself some typing, use the dev scripts.
+[install-hdl-apt-reqs](https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=install-hdl-apt-reqs;hb=HEAD)
+script will install the qemu;
+[ppc64-gdb-gcc](https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=ppc64-gdb-gcc;hb=HEAD)
+script will install the toolchain and the corresponding debugger.
+The steps are provided below only for reference; when in doubt,
+consider checking and running the scripts.
+
+Install powerpc64 gcc:
+
+ apt-get install gcc-8-powerpc64-linux-gnu
+
+Install qemu:
+
+ apt-get install qemu-system-ppc
+
+Install gdb from source. Obtain the required tarball matching
+the version of gcc (8.3) from here <https://ftp.gnu.org/gnu/gdb/>,
+unpack it, then:
+
+ cd gdb-8.3 (or other location)
+ mkdir build
+ cd build
+ ../configure --srcdir=.. --host=x86_64-linux --target=powerpc64-linux-gnu
+ make -j$(nproc)
+ make install
+
+[gdb](https://en.wikipedia.org/wiki/GNU_Debugger) lets you debug running
+programs. [qemu](https://www.qemu.org/) emulates processors, you can
+run programs under qemu.
+
+## power-instruction-analyzer (pia)
+
+We have a custom tool built in Rust by programmerjake to help analyze
+the OpenPower instructions' execution on *actual* hardware.
+
+Install Rust:
+
+ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+
+Make sure we have the correct and up-to-date rust compiler (rustc & cargo):
+
+ rustup default stable
+ rustup update
+
+Install the Python extension from git source by doing the following:
+
+ git clone https://salsa.debian.org/Kazan-team/power-instruction-analyzer.git pia
+ cd pia
+ ./libre-soc-install.sh
+
+## Chips4Makers JTAG
+
+As this is an actual ASIC, we do not rely on an FPGA's JTAG TAP
+interface, instead require a full complete independent implementation
+of JTAG. Staf Verhaegen has one, with a full test suite, and it is
+superb and well-written. The Libre-SOC version includes DMI (Debug
+Memory Interface):
+
+ git clone https://git.libre-soc.org/git/c4m-jtag.git/
+ cd c4m-jtag
+ python3 setup.py develop
+
+Included is an IDCODE tap point, Wishbone Master (for direct memory read
+and write, fully independent of the core), IOPad redirection and testing,
+and general purpose shift register capability for any custom use.
+
+We added a DMI to JTAG bridge in LibreSOC which is
+directly connected to the core, to access registers and
+to be able to start and stop the core and change the PC.
+In combination with the JTAG Wishbone interface the test
+[ASIC](https://en.wikipedia.org/wiki/Application-specific_integrated_circuit)
+can have a bootloader uploaded directly into onboard
+[SRAM](https://en.wikipedia.org/wiki/Static_random-access_memory) and
+execution begun.
+
+[Chips4Makers](https://chips4makers.io/) make it possible for makers
+and hobbyists to make their own open source chips.
+
+[JTAG](https://en.wikipedia.org/wiki/JTAG) (Joint Test Action Group) is
+an industry standard for verifying designs and testing printed circuit
+boards after manufacture.
+
+The [Wishbone
+bus](https://en.wikipedia.org/wiki/Wishbone_%28computer_bus%29) is an open
+source hardware computer bus intended to let the parts of an integrated
+circuit communicate with each other.
+
## Coriolis2
+See [[HDL_workflow/coriolis2]] page, for those people doing layout work.
+
+## Nextpnr
+
+A portable FPGA place and route tool.
+
+See [[HDL_workflow/nextpnr]] page for installation instructions of nextpnr with ECP5 support for Lattice FPGA ECP5 series. Also see
+[[HDL_workflow/ECP5_FPGA]] for connecting up to JTAG with a ULX3S
+and the Lattice VERSA_ECP5.
+
+## Verilator
+
+The fastest Verilog and SystemVerilog simulator. It compiles Verilog to C++ or SystemC.
+
+Advise use only v4.106 at the moment.
+
+See [[HDL_workflow/verilator]] page for installation instructions.
+
+## GHDL
+
+GHDL is a shorthand for G Hardware Design Language. It is a VHDL analyzer, compiler, simulator and (experimental) synthesizer that can process (nearly) any VHDL design.
+
+VHDL is an acronym for Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (HDL), which is a programming language used to describe a logic circuit by function, data flow behavior, or structure.
+
+Unlike some other simulators, GHDL is a compiler: it directly translates a VHDL file to machine code, without using an intermediary language such as C or C++. Therefore, the compiled code should be faster and the analysis time should be shorter than with a compiler using an intermediary language.
+
+GHDL aims at implementing VHDL as defined by IEEE 1076. It supports the 1987, 1993 and 2002 revisions and, partially, 2008. PSL is also partially supported.
+
+See [[HDL_workflow/ghdl]] page for installation instructions.
+
+## Icarus Verilog
+
+Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format.
-See [[coriolis2]] page, for those people doing layout work.
+See [[HDL_workflow/iverilog]] page for installation instructions.
-# Registering for git repository access
+## Cocotb
+
+cocotb is a COroutine based COsimulation TestBench environment for verifying VHDL and SystemVerilog RTL using Python.
+
+See [[HDL_workflow/cocotb]] page for installation instructions.
+
+## Symbiflow
+
+A fully open source toolchain for the development of FPGAs. Currently it targets Xilinx 7-series, Lattice iCE40 and ECP5, Quicklogic EOS S3.
+
+Needed for the Arty A7 100t Digilent FPGA board.
+
+See [[HDL_workflow/symbiflow]] for installation instructions
+and dependencies.
+
+# Registering for git repository access<a name="gitolite3_access"></a>
After going through the onboarding process and having agreed to take
responsibility for certain tasks, ask on the mailing list for git
-repository access, sending in a public key (id_rsa.pub). If you do
-not have one then generate it with ssh-keygen -t rsa. You will find it
-in ~/.ssh
+repository access, sending in a public key (`id_rsa.pub`). If you do
+not have one then generate it with `ssh-keygen -t rsa`. You will find it
+in `~/.ssh`
NEVER SEND ANYONE THE PRIVATE KEY. By contrast the public key, on
account of being public, is perfectly fine to make... err... public.
-Create a file ~/.ssh/config with the following lines:
+Create a file `~/.ssh/config` with the following lines:
- Host git.libre-riscv.org
+ Host git.libre-soc.org
Port 922
+Test that you have access with this command:
+
+ ssh -v -p922 gitolite3@git.libre-soc.org
+
+Please note: **DO NOT TYPE A PASSWORD** - the server gets hit by a lot of
+port-scanning, and detection of password failures are used to instantly
+ban IP addresses.
+
Wait for the Project Admin to confirm that the ssh key has been added
to the required repositories. Once confirmed, you can clone any of the
-repos at http://git.libre-riscv.org:
+repos at https://git.libre-soc.org/:
- git clone gitolite3@git.libre-riscv.org:REPONAME.git
+ git clone gitolite3@git.libre-soc.org:REPONAME.git
Alternatively, the .ssh/config can be skipped and this used:
- git clone ssh://gitolite3@git.libre-riscv.org:922/REPONAME.git
+ git clone ssh://gitolite3@git.libre-soc.org:922/REPONAME.git
+
+Note: **DO NOT ATTEMPT TO LOG IN TO THE SERVER WITH A PERSONAL ACCOUNT**.
+fail2ban is running and, due to repeated persistent port-scanning spammers
+is set up to instantly ban any unauthorised ssh access for up to two weeks.
+This keeps log file sizes down on the server (which is resource-constrained).
+If you are wondering why this is done, it's a *lot* of port-scans.
+
+Therefore, *only* ssh in to server with the gitolite3 account, *only*
+on port 922, and *only* once the systems administrator has given you
+the all-clear that the ssh key has been added.
# git configuration
# Checking out the HDL repositories
+Before running the following, install the
+dependencies. This is easiest done with this script
+<https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=install-hdl-apt-reqs;hb=HEAD>
+
+**It is critically important to install these in STRICT order, otherwise
+pip3 interferes and performs unauthorised downloads without informing
+you of what it is doing**.
+
* mkdir ~/src
* cd !$
-* git clone gitolite3@git.libre-riscv.org:nmutil.git
-* git clone gitolite3@git.libre-riscv.org:ieee754fpu.git
-* git clone gitolite3@git.libre-riscv.org:soc.git
+* git clone gitolite3@git.libre-soc.org:nmigen.git
+* git clone gitolite3@git.libre-soc.org:c4m-jtag.git
+* git clone gitolite3@git.libre-soc.org:nmutil.git
+* git clone gitolite3@git.libre-soc.org:openpower-isa.git
+* git clone gitolite3@git.libre-soc.org:ieee754fpu.git
+* git clone gitolite3@git.libre-soc.org:nmigen-soc.git
+* git clone gitolite3@git.libre-soc.org:soc.git
-In each of these directories, in the order listed, track down the
-setup.py file, then, as root (sudo bash), run the following:
+In each of these directories, **in the order listed***, track down the
+`setup.py` file, then, as root (`sudo bash`), run the following:
* python3 setup.py develop
own machine these days.
The reason for the order is because soc depends on ieee754fpu, and
-ieee754fpu depends on nmutil
+ieee754fpu depends on nmutil. If you do not follow the listed order
+pip3 will go off and download an arbitrary version without your
+consent.
-If "python3 setup.py install" is used it is a pain: edit, then
+If "`python3 setup.py install`" is used it is a pain: edit, then
install. edit, then install. It gets extremely tedious, hence why
"develop" was created.
+If you prefer you can use this script instead: of course you checked it
+in advance and accept full responsibility.
+<https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=hdl-dev-repos;hb=HEAD>
+
# Development Rules
-team communication:
+Team communication:
+* new members, add yourself to the [[about_us]] page and create yourself
+ a home page using someone else's page as a template.
* communicate on the mailing list or the bugtracker an intent to take
responsibility for a particular task.
* assign yourself as the bug's owner
* *keep in touch* about what you are doing, and why you are doing it.
+* edit your home page regularly, particularly to track tasks so that
+ they can be paid by NLNet.
* if you cannot do something that you have taken responsibility for,
then unless it is a dire personal emergency please say so, on-list. we
won't mind. we'll help sort it out.
-regarding the above it is important that you read, understand, and agree
+Regarding the above it is important that you read, understand, and agree
to the [[charter]] because the charter is about ensuring that we operate
as an effective organisation. It's *not* about "setting rules and meting
out punishment".
-for actual code development:
+## Coding
+
+for actual code development
+
+### Plan unit tests
* plan in advance to write not just code but a full test suite for
that code. **this is not optional**. large python projects that do not
have unit tests **FAIL** (see separate section below).
+* Prioritise writing formal proofs and a single clear unit test that is more
+ like a "worked example".
+ We receive NLNet funds for writing formal proofs, plus they
+ cover corner cases and take far less time to write
+
+### Commit tested or zero-dependent code
+
* only commit code that has been tested (or is presently unused). other
people will be depending on you, so do take care not to screw up.
not least because, as it says in the [[charter]] it will be your
responsibility to fix. that said, do not feel intimidated: ask for help
and advice, and you'll get it straight away.
+
+### Commit often
+
* commit often. several times a day, and "git push" it. this is
collaboration. if something is left even overnight uncommitted and not
- pushed so that other people can see it, it is a red flag. if you find
+ pushed so that other people can see it, it is a red flag.
+* if you find
yourself thinking "i'll commit it when it's finished" or "i don't want to
commit something that people might criticise" *this is not collaboration*,
it is making yourself a bottleneck. pair-programming is supposed to help
avoid this kind of thing however pair-programming is difficult to organise
for remote collaborative libre projects (suggestions welcomed here)
+
+### Enable editor auto-detection of file changes by external programs
+
+This is important. "`git pull`" will merge in changes. If you then
+arbitrarily save a file without re-loading it, you risk destroying
+other people's work.
+
+You can avoid damaging the repositories by following some simple procedures:
+
+ run appropriate unit tests
+ git pull
+ run appropriate unit tests again (checks other people's work)
+ git diff # and actually read and review the output
+ git status # check for any missing files
+ git commit # with appropriate arguments and message
+ git push # always always always do this
+
+### Absolutely no auto-generated output
+
* **do not commit autogenerated output**. write a shell script and commit
- that, or add a Makefile to run the command that generates the output, but
+ that, or add a `Makefile` to run the command that generates the output, but
**do not** add the actual output of **any** command to the repository.
ever. this is really important. even if it is a human-readable file
rather than a binary object file.
- it is very common to add pdfs (the result of running latex2pdf) or configure.in (the result of running automake), they are an absolute nuisance and interfere hugely with git diffs, as well as waste hard disk space *and* network bandwidth. don't do it.
+* it is very common to add PDFs (the result of running `latex2pdf`) or
+ configure.in (the result of running `automake`), they are an absolute
+ nuisance and interfere hugely with git diffs, as well as waste hard
+ disk space *and* network bandwidth. don't do it.
+* do not add multi-megabyte or multi-gigabyte "test data".
+ use shell scripts and commit that, which automatically downloads the
+ "test data" from a well-known known-good reliable location instead.
+
+### Write commands that do tasks and commit those
+
* if the command needed to create any given autogenerated output is not
currently in the list of known project dependencies, first consult on
the list if it is okay to make that command become a hard dependency of
* if you find yourself repeating commands regularly, chances are high
that someone else will need to run them, too. clearly this includes
yourself, therefore, to make everyone's lives easier including your own,
- put them into a .sh shell script (and/or a Makefile), commit them to
+ put them into a `.sh` shell script (and/or a `Makefile`), commit them to
the repository and document them at the very minimum in the README,
INSTALL.txt or somewhere in a docs folder as appropriate. if unsure,
ask on the mailing list for advice.
+
+### Keep commits single-purpose
+
* edit files making minimal *single purpose* modifications (even if
it involves multiple files. Good extreme example: globally changing
a function name across an entire codebase is one purpose, one commit,
yet hundreds of files. miss out one of those files, requiring multiple
commits, and it actually becomes a nuisance).
+
+### Run unit tests prior to commits
+
* prior to committing make sure that relevant unit tests pass, or that
the change is a zero-impact addition (no unit tests fail at the minimum)
-* keep working code working **at all times**. find ways to ensure that this is the case. examples include writing alternative classes that replace existing functionality and adding runtime optiobs to select between old and new code.
+
+### Do not break existing code
+
+* keep working code working **at all times**. find ways to ensure that
+ this is the case. examples include writing alternative classes that
+ replace existing functionality and adding runtime options to select
+ between old and new code.
+
+### Small commits with relevant commit message
+
* commit no more than around 5 to 10 lines at a time, with a CLEAR message
(no "added this" or "changed that").
* if as you write you find that the commit message involves a *list* of
changes or the word "and", then STOP. do not proceed: it is a "red flag"
that the commit has not been properly broken down into separate-purpose
commits. ask for advice on-list on how to proceed.
+
+### Exceptions to small commit: atomic single purpose commit
+
* if it is essential to commit large amounts of code, ensure that it
is **not** in use **anywhere** by any other code. then make a *small*
(single purpose) followup commit which actually puts that code into use.
-this last rule is kinda flexible, because if you add the code *and* add
+This last rule is kinda flexible, because if you add the code *and* add
the unit test *and* added it into the main code *and* ran all relevant
unit tests on all cascade-impacted areas by that change, that's perfectly
fine too. however if it is the end of a day, and you need to stop and
change which integrates untested code: just commit the new code (only)
and follow up the next day *after* running the full relevant unit tests.
-the reason for all the above is because python is a weakly typed language.
-make one tiny change at the base level of the class hierarchy and the
-effect may be disastrous.
+### Why such strict rules?
-it is therefore worth reiterating: make absolutely certain that you *only*
+The reason for all the above is because python is a dynamically typed
+language. make one tiny change at the base level of the class hierarchy
+and the effect may be disastrous.
+
+It is therefore worth reiterating: make absolutely certain that you *only*
commit working code or zero-impact code.
-therefore, if you are absolutely certain that a new addition (new file,
+Therefore, if you are absolutely certain that a new addition (new file,
new class, new function) is not going to have any side-effects, committing
it (a large amount of code) is perfectly fine.
-as a general rule, however, do not use this an an excuse to write code
+As a general rule, however, do not use this an an excuse to write code
first then write unit tests as an afterthought. write *less* code *in
conjunction* with its (more basic) unit tests, instead. then, folliw up with
additions and improvements.
-the reason for separating out commits to single purpose only becomes
+The reason for separating out commits to single purpose only becomes
obvious (and regretted if not followed) when, months later, a mistake
has to be tracked down and reverted. if the commit does not have an
easy-to-find message, it cannot even be located, and once found, if the
commit confuses several unrelated changes, not only the diff is larger
than it should be, the reversion process becomes extremely painful.
+### PEP8 format
+
* all code needs to conform to pep8. use either pep8checker or better
run autopep8. however whenever committing whitespace changes, *make a
separate commit* with a commit message "whitespace" or "autopep8 cleanup".
you think you need greater than 80 chars, it *fundamentally* indicates
poor code design. split the code down further into smaller classes
and functions.
+
+### Docstring checker
+
* TBD there is a docstring checker. at the minimum make sure to have
an SPD license header, module header docstring, class docstring and
function docstrings on at least non-obvious functions.
+
+### Clear code commenting and docstrings
+
* make liberal but not excessive use of comments. describe a group of
lines of code, with terse but useful comments describing the purpose,
documenting any side-effects, and anything that could trip you or other
developers up. unusual coding techniques should *definitely* contain
a warning.
+
+### Only one class per module (ish)
+
* unless they are very closely related, only have one module (one class)
per file. a file only 25 lines long including imports and docstrings
is perfectly fine however don't force yourself. again, if unsure,
ask on-list.
+
+### File and Directory hierarchy
+
* *keep files short and simple*. see below as to why
* create a decent directory hierarchy but do not go mad. ask for advice
if unsure
+
+### No import star!
+
* please do not use "from module import \*". it is extremely bad practice,
causes unnecessary resource utilisation, makes code readability and
tracking extremely difficult, and results in unintended side-effects.
+
+Example: often you want to find the code from which a class was imported.
+nirmally you go to the top of the file, check the imports, and you know
+exactly which file has the class because of the import path. by using
+wildcards, you have absolutely *no clue* which wildcard imported which
+class or classes.
+
+Example: sometimes you may accidentally have duplicate code maintained
+in two or more places. editing one of them you find, puzzlingly, that
+the code behaves in some files with the old behaviour, but in others it
+works. after a massive amount of investigation, you find that the working
+files happen to have a wildcard import of the newer accidental duplicate
+class **after** the wildcard import of the older class with exactly the
+same name. if you had used explicit imports, you would have spotted
+the double import of the class from two separate locations, immediately.
+
+Really. don't. use. wildcards.
+
+### Keep file and variables short but clear
+
* try to keep both filenames and variable names short but not ridiculously
obtuse. an interesting compromise on imports is "from ridiculousfilename
import longsillyname as lsn", and to assign variables as well: "comb =
m.d.comb" followed by multiple "comb += nmigen_stmt" lines is a good trick
that can reduce code indentation by 6 characters without reducing clarity.
-regarding code structure: we decided to go with small modules that are
+Additionally, use comments just above an obtuse variable in order to
+help explain what it is for. In combination with keeping the the module
+itself short, other readers will not need to scroll back several pages
+in order to understand the code.
+
+Yes it is tempting to actually use the variables as
+self-explanatory-comments and generally this can be extremely good
+practice. the problem comes when the variable is so long that a function
+with several parameters csn no longer fit on a single line, and takes
+up five to ten lines rather than one or two. at that point, the length
+of the code is adversely affected and thus so is readability by forcing
+readers to scroll through reams of pages.
+
+It is a tricky balance: basically use your common sense, or just ask
+someone else, "can you understand this code?"
+
+### Reasons for code structure
+
+Regarding code structure: we decided to go with small modules that are
both easy to analyse, as well as fit onto a single page and be readable
when displayed as a visual graph on a full UHD monitor. this is done
as follows:
show, then space, then pressing the tab key twice will give a full list
of submodules (one of which will be "top")
-you can now fullsize the graphviz window and scroll around. if it looks
+You can now fullsize the graphviz window and scroll around. if it looks
reasonably obvious at 100% zoom, i.e the connections can be clearly
related in your mind back to the actual code (by matching the graph names
against signals and modules in the original nmigen code) and the words are
* thirdly, unit testing, particularly formal proofs, is far easier on
small sections of code, and complete in a reasonable time.
+## Special warning / alert to vim users!
+
+Some time around the beginning of 2019 some bright spark decided that
+an "auto-recommend-completion-of-stuff" option would be a nice, shiny
+idea to enable by default from that point onwards.
+
+This incredibly annoying "feature" results in tabs (or spaces) being
+inserted "on your behalf" when you press return on one line, for your
+"convenience" of not needing to type lots of spaces/tabs just to get
+to the same indentation level.
+
+Of course, this "feature", if you press return on one line in edit
+mode and then press "escape", leaves a bundle-of-joy extraneous
+whitespace **exactly** where you don't want it, and didn't ask for it,
+pooped all over your file.
+
+Therefore, *please*: **before** running "git commit", get into the
+habit of always running "git diff", and at the very minimum
+speed-skim the entire diff, looking for tell-tale "red squares"
+(these show up under bash diff colour-syntax-highlighting) that
+inform you that, without your knowledge or consent, vim has
+"helpfully" inserted extraneous whitespace.
+
+Remove them **before** git committing because they are not part
+of the actual desired code-modifications, and committing them
+is a major and constant distraction for reviewers about actual
+important things like "the code that actually *usefully* was
+modified for that commit"
+
+This has the useful side-effect of ensuring that, right before
+the commit, you've got the actual diff right in front of you
+in the xterm window, on which you can base the "commit message".
+
## Unit tests
+For further reading, see the wikipedia page on
+[Test-driven Development](https://en.wikipedia.org/wiki/Test-driven_development)
+
This deserves its own special section. It is extremely important to
appreciate that without unit tests, python projects are simply unviable.
Python itself has over 25,000 individual tests.
black art. This is where team collaboration particularly kicks in,
so if you need help, ask on the mailing list.
+## Don't comment out unit tests: add them first (as failures) and fix code later
+
+Unit tests serve an additional critical purpose of keeping track of code
+that needs to be written. In many cases, you write the unit test *first*,
+despite knowing full well that the code doesn't even exist or is completely
+broken. The unit test then serves as a constant and important reminder
+to actually fix (or write) the code.
+
+Therefore, *do not* comment out unit tests just because they "don't work".
+If you absolutely must stop a unit test from running, **do not delete it**.
+Simply mark it with an appropriate
+["skip" decorator](https://docs.python.org/3/library/unittest.html#skipping-tests-and-expected-failures),
+preferably with a link to a URL in the [bugtracker](https://bugs.libre-soc.org/)
+with further details as to why the unit test should not be run.
+
# TODO Tutorials
Find appropriate tutorials for nmigen and yosys, as well as symbiyosys.
+* Robert Baruch's nmigen tutorials look really good:
+ <https://github.com/RobertBaruch/nmigen-tutorial>
* Although a verilog example this is very useful to do
<https://symbiyosys.readthedocs.io/en/latest/quickstart.html#first-step-a-simple-bmc-example>
* This tutorial looks pretty good and will get you started
- <http://blog.lambdaconcept.com/doku.php?id=nmigen:nmigen_install> and
- walks not just through simulation, it takes you through using gtkwave
- as well.
+ <https://web.archive.org/web/20210123052724/http://blog.lambdaconcept.com/doku.php?id=nmigen:nmigen_install>
+ and walks not just through simulation, it takes you through using
+ gtkwave as well.
* There exist several nmigen examples which are also executable
- <https://github.com/m-labs/nmigen/tree/master/examples/> exactly as
+ <https://github.com/nmigen/nmigen/tree/master/examples/> exactly as
described in the above tutorial (python3 filename.py -h)
+* More nmigen tutorials at [[learning_nmigen]]
projects / libreriscv.git / blobdiff