X-Git-Url: https://git.libre-soc.org/?a=blobdiff_plain;f=HDL_workflow.mdwn;h=6530120fff7b788ee79363e0caaacc8428faa165;hb=55ac96a7c0ae1507717187a488bdc1f42df3e1c5;hp=417245f3f8c877b59369eeb2b7a760f3d22e41e7;hpb=e42f38596abd9568ae54996838c15726cce43ca0;p=libreriscv.git

diff --git a/HDL_workflow.mdwn b/HDL_workflow.mdwn
index 417245f3f..6530120ff 100644
--- a/HDL_workflow.mdwn
+++ b/HDL_workflow.mdwn
@@ -1,63 +1,319 @@
 # HDL workflow
 
-This section describes the workflow for developing the LibreSoC.  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.
+This section describes the workflow and some best practices for developing
+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.
+
+It is particularly important to bear in mind that we are not just
+"developing code", here: we are creating a "lasting legacy educational
+resource" for other people to learn from, and for businesses and students
+alike to be able to use, learn from and augment for their own purposes.
+
+It is also important to appreciate and respect that we are funded under
+NLNet's Privacy and Enhanced Trust Programme <http://nlnet.nl/PET>. Full
+transparency, readability, documentation, effective team communication
+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.
+* 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 file store.
+
+we will add an IRC channel at some point when there are enough people
+to warrant having one (and it will be publicly archived)
+
+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. <https://lists.libre-soc.org/mailman/listinfo/libre-riscv-dev>
+therefore please do google "mailing list etiquette" and at the very
+minimum look up and understand the following:
+
+* This is a technical mailing list with complex topics. Top posting
+  is completely inappropriate. Don't do it unless you have mitigating
+  circumstances, and even then please apologise and explain ("hello sorry
+  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") 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
+  indentation of other people's replies.  If using gmail, please: SWITCH
+  OFF RICH TEXT EDITING.
+* Please for god's sake do not use "my replies are in a different
+  colour". Only old and highly regarded people still using AOL are allowed
+  to get away with that (such as Mitch).
+* Start a new topic with a relevant subject line. If an existing
+  discussion changes direction, change the subject line to reflect the
+  new topic (or start a new conversation entirely, without using the
+  "reply" button)
+* DMARC is a pain on the neck. Try to avoid GPG signed messages. sigh.
+* Don't send massive attachments. Put them online (no, not on facebook or
+  google drive or anywhere else that demands privacy violations) and provide
+  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 <https://lists.libre-soc.org/pipermail/libre-riscv-dev/>,
+and put the link actually in the bugtracker as one of the comments.
+
+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
+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 <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
 
-It is particularly important to bear in mind that we are not just "developing code", here: we are creating a "lasting legacy educational resource" for other people to learn from, and for businesses and students alike to be able to use, learn from and augment for their own purposes.
+bugzilla. old and highly effective. sign up in the usual way. any
+problems, ask on the list.
+
+Please do not ask for the project to be transferred to github or other
+proprietary nonfree service "because it's soooo convenient", as the
+lions are getting wind and gout from overfeeding on that one.
 
-It is also important to appreciate and respect that we are funded under NLNet's Privacy and Enhanced Trust Programme <http://nlnet.nl/PET>. Full transparency, readability, documentation, effective team communication and formal mathematical proofs for all code at all levels is therefore paramount.
+## ikiwiki
 
-# Hardware
-
-RAM is the biggest requirement. Minimum 16GB, the more the better (32 or 64GB starts to reach "acceptable" levels.  Disk space is not hugely critical: 256GB SSD should be more than adequate.  Simulations and FPGA compilations however are where raw processing power is a must.  High end Graphics Cards are nonessential.
-
-What is particularly useful is to have not only hi-res screens (curved is *strongly* recommended if the LCD is over 24in wide, to avoid eyeballs going "prism"), and to have several of them: the more the better.  Either a DisplayLink UD160A (or more modern variant) or simply using a second (lower spec hardware) machine is really 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.
+
+Usual deal: register an account and you can start editing and contributing
+straight away.
+
+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
+next to the new link you created.  click that link, and it will fire up a
+"create new page" editor.
+
+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
+reverted or edited by the sysadmins to restore things if you get in a tiz.
+
+Assistance in creating a much better theme greatly appreciated.  e.g.
+<http://www.math.cmu.edu/~gautam/sj/blog/20140720-ikiwiki-navbar.html>
+
+## 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.
+
+gitweb is provided which does a decent job. <https://git.libre-soc.org/>
+
+## 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.
 
-Also it is really recommended to have a UHD monitor (4k - 3840x2160), or at least 2560x1200.  If given a choice, 4:3 aspect ratio is better than 16:9 particularly when using several of them. However, caveat (details below): please when editing do not assume that everyone will have access to such high resolution screens.
-
-# Operating System
+ask on the list if you have a file that belongs on the ftp server.
 
-First install and become familiar with Debian (ubuntu 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.
+## server
 
-Only a basic GUI desktop is necessary: fvwm2, xfce4, lxde are perfectly sufficient (alongside wicd-gtk for network management). Other more complex desktops can be used however may consume greater resources.
+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.
 
-# editors and editing
+we tried gitlab. it didn't go well. please don't ask to replace the
+above extremely resource-efficient services with it.
 
-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 *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.
+# Hardware
 
-At the point where such fullscreen users commit code with line lengths well over 160 characters, that amusement quickly evaporates.
+RAM is the biggest requirement. Minimum 16GB, the more the better (32
+or 64GB starts to reach "acceptable" levels.  Disk space is not hugely
+critical: 256GB SSD should be more than adequate.  Simulations and
+FPGA compilations however are where raw processing power is a must.
+High end Graphics Cards are nonessential.
+
+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
+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.
+
+Also it is really recommended to have a UHD monitor (4k - 3840x2160),
+or at least 2560x1200.  If given a choice, 4:3 aspect ratio is better
+than 16:9 particularly when using several of them. However, caveat
+(details below): please when editing do not assume that everyone will
+have access to such high resolution screens.
 
-Where the problems occur with fullscreen 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 hidden tabs, next to at least two if not three additional free and clear terminals into which commands are regularly and routinely  typed (make, git commit, nosetests3 etc).
+# Operating System
 
-(hint/tip: fvwm2 set up with "mouse-over to raise focus, rather than additionally requiring a mouseclick, can save a huge amount of cumulative development time here, switching between editor terminal(s) and the command terminals).
+First install and become familiar with Debian (ubuntu 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.
 
-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.
+Only a basic GUI desktop is necessary: fvwm2, xfce4, lxde are perfectly
+sufficient (alongside wicd-gtk for network management). Other more
+complex desktops can be used however may consume greater resources.
 
-Additionally, care should be taken to respect that not everyone will have 200+ column editor windows. They may only have a 1280 x 800 laptop which barely fits 2 80x53 xterms side by side.  Consequently, having excessively long functions is also a hindrance to others, as such developers with limited screen resources would need to continuously page-up and page-down to read the code even of a single function, in full.
+# editors and editing
 
-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.
+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
+*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
+well over 160 characters, that amusement quickly evaporates.
+
+Where the problems occur with fullscreen 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
+hidden tabs, next to at least two if not three additional free and clear
+terminals into which commands are regularly and routinely  typed (make,
+git commit, nosetests3 etc).  Illustrated with the following 3840x2160
+screenshot (click to view full image), where *every one* of those 80x70
+xterm windows is *relevant to the task at hand*.
+
+[[!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
+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.
+
+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
+a 1280 x 800 laptop which barely fits two 80x53 xterms side by side.
+Consequently, having excessively long functions is also a hindrance to
+others, as such developers with limited screen resources would need to
+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.
+
+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.
 
 # Software prerequisites
 
-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.
+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 graphviz xdot
+* apt-get install graphviz xdot gtkwave
+* apt-get install python3-venv
+* apt-get install python-virtualenv  # this is an alternative to python3-venv
 * 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.
+
+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.
+
+## git
+
+Look up good tutorials on how to use git effectively.  There are so many
+it is hard to recommend one. This is however essential. If you are not
+comfortable with git, and you let things stay that way, it will seriously
+impede development progress.
+
+If working all day you should expect to be making at least two commits per
+hour, so should become familiar with it very quickly.  If you are *not*
+doing around 2 commits per hour, something is wrong and you should read
+the workflow instructions below more carefully, and also ask for advice
+on the mailing list.
+
+Worth noting: *this project does not use branches*. All code is committed
+to master and we *require* that it be either zero-impact additions or that
+relevant unit tests pass 100%.  This ensures that people's work does not
+get "lost" or isolated and out of touch due to major branch diversion,
+and that people communicate and coordinate with each other.
+
 ## yosys
 
-Follow the source code (git clone) instructions here: <http://www.clifford.at/yosys/download.html>
+Follow the source code (git clone) instructions here:
+<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
+[yosys-et-al](https://git.libre-soc.org/?p=dev-env-setup.git;a=blob;f=yosys-et-al;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.
 
 ## symbiyosys
 
-Follow the instructions here: <https://symbiyosys.readthedocs.io/en/latest/quickstart.html#installing>
+Follow the instructions here:
+<https://symbiyosys.readthedocs.io/en/latest/quickstart.html#installing>
 
-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).
+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).
 
 ## nmigen
 
@@ -65,83 +321,564 @@ nmigen 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 setp.py test"
+testing can then be carried out with "python3 setup.py test"
+
+## Softfloat and sfpy
+
+These are a test suite dependency for the 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
+    cd SoftPosit
+    git apply ../softposit_sfpy_build.patch
+    git apply /path/to/ieee754fpu/SoftPosit.patch
+    cd ../berkely-softfloat-3
+    # Note: Do not apply the patch included in sfpy for berkely-softfloat, 
+    # it contains the same changes as this one
+    git apply /path/to/ieee754fpu/berkeley-softfloat.patch
+    cd ..
+
+    # prepare a virtual environment for building
+    python3 -m venv .env
+
+    # 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 -j$(nproc)
+    make cython
+    make inplace -j$(nproc)
+    make wheel
+
+    # install
+    deactivate # deactivates venv, optional 
+    pip3 install dist/sfpy*.whl
+
+You can test your installation by doing the following:
+
+    python3
+    >>> from sfpy import *
+    >>> 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.
+
+Install powerpc64 gcc:
+
+    apt-get install gcc-9-powerpc64-linux-gnu
+
+Install qemu:
+
+    apt-get install qemu-system-ppc
+
+Install gdb from source.  Obtain the latest tarball, unpack it, then:
+
+    cd gdb-9.1 (or other location)
+    mkdir build
+    cd build
+     ../configure --srcdir=.. --host=x86_64-linux --target=powerpc64-linux-gnu
+    make -j$(nproc)
+    make install
+
+## power_instruction_analyzer (pia)
+
+We have a custom tool built in rust by programmerjake to help analyze
+the power instructions execution on *actual* hardware.
+
+Note: a very recent version of pip3 is required for this to work.
+
+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):
+
+    rustup default stable
+    rustup update
+
+Use rust's package manager *cargo* to install the rust-python build tool maturin:
+
+    cargo install maturin
+
+Install from git source by doing the following:
+
+    git clone https://salsa.debian.org/Kazan-team/power-instruction-analyzer.git pia
+    cd pia
+    maturin build --cargo-extra-args=--features=python-extension
+    python3 -m pip install --user target/wheels/*.whl
+
+Note: an ongoing bug in maturin interferes with successful installation.  This can be worked around by explicitly installing only the .whl files needed rather than installing everything (*.whl).
+
+## Coriolis2
+
+See [[HDL_workflow/coriolis2]] page, for those people doing layout work.
+
+## 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.
+
+    git clone https://gitlab.com/Chips4Makers/c4m-jtag.git
+
+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 can have a bootloader uploaded directly into onboard SRAM and execution begun.
 
 # Registering for git repository access
 
-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 generate it with ssh-keygen -t rsa.
+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
 
-NEVER SEND ANYONE THE PRIVATE KEY.  By contrast the public key, on account of being public, is perfectly fine to make... err... public.
+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:
 
-    Host git.libre-riscv.org
+    Host git.libre-soc.org
     Port 922
 
-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:
+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 https://git.libre-soc.org/:
+
+    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-soc.org:922/REPONAME.git
+
+# git configuration
+
+Although there are methods online which describe how (and why) these
+settings are normally done, honestly it is simpler and easier to open
+~/.gitconfig and add them by hand.
 
-    git clone gitolite3@git.libre-riscv.org:REPONAME.git
+core.autocrlf is a good idea to ensure that anyone adding DOS-formatted
+files they don't become a pain.  pull.rebase is something that is greatly
+preferred for this project because it avoids the mess of "multiple
+extra merge git tree entries", and branch.autosetuprebase=always will,
+if you want it, always ensure that a new git checkout is set up with rebase.
+
+    [core]
+        autocrlf = input
+    [push]
+        default = simple
+    [pull]
+        rebase = true
+    [branch]
+        autosetuprebase = always
+
+# Checking out the HDL repositories
+
+* mkdir ~/src
+* cd !$
+* git clone gitolite3@git.libre-soc.org:nmutil.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:
+
+* python3 setup.py develop
+
+The reason for using "develop" mode is that the code may be edited
+in-place yet still imported "globally".  There are variants on this theme
+for multi-user machine use however it is often just easier to get your
+own machine these days.
+
+The reason for the order is because soc depends on ieee754fpu, and
+ieee754fpu depends on nmutil
+
+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.
 
 # Development Rules
 
 team communication:
 
-* communicate on the mailing list or the bugtracker an intent to take responsibility for a particular task.
+* 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.
-* if you cannot do sonething that you gave taken responsibility for, then unless it is a dire emergency please say so, on-list. we won't mind. we'll help sort it out.
+* *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
+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".
+
+## 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
+  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.
+
+### 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
+  **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.
+
+### 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
+  the project (hint: java, node.js php and .NET commands may cause delays
+  in response time due to other list participants laughing hysterically),
+  and after a decision is made, document the dependency and how its source
+  code is obtained and built (hence why it has to be discussed carefully)
+* 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
+  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)
+
+### 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
 
-for actual code development:
+* 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.
 
-* **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 **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.
-* if the command needed to create any given autogenerated output is not currently in the list of dependencies, first consult on the list if it is okay to make that command become a hard dependency of the project (hint: java, node.js php and .NET commands will cause delays in responses due to list participants laughing hysterically too much), and after a decision is made, document the dependency and how its source code is obtained and built.
-* if you find yourself repeating commands regularly, chances are high that someone else will need to run them, too. therefore, put them into a .sh shell script (and/or a Makefile) and document them at the very minimum in README or INSTALL.txt or somewhere in a docs folder as appopriate.  if unsure, ask on the mailing list for advice.
-* 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**.
-* edit files making minimal *single purpose* modifications.
-* prior to committing make sure that relevant unit tests pass, or that the change is a zero-impact addition.
-* commit no more than 5 to 10 lines at a time, with a CLEAR message (no "added this" or "changed that").
-* if 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. ask for advice on-list.
-* if it is essential to commit large amounts of code, ensure that it is **not** in use **anywhere** by any other code.
+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
+do not have time to run the necessary unit tests, do *not* commit the
+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 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?
+
+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, new class, new function) is not going to have any side-effects, committing it (a large amount of code) is perfectly fine.
+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
+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
+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.
 
-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.
+### 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".
-* pep8 REQUIRES no more than 80 chars per line. this is non-negotiable. if you think you need greater than 80 chars, it *fundamentally* indicates poor code design. split the code down further into smaller classes and functions.
-* TBD there is a docstring checker.  at the minimum make sure to have an SPD license heafer, module header docstring, class docstring and function docstrings on non-obvious functions
-* make liberal but not excessive use of comments.
-* 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.
-* *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
-* please do not use "from module import *". it is extremely bad practice, causes unnecessary resource utilisation, makes code readability extremely difficult, and results in unintended side-effects.
-* 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 += nmigenstmt" lines is a good trick that can reduce code indentation by 6 characters without reducing clarity.
+* 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".
+* pep8 REQUIRES no more than 80 chars per line. this is non-negotiable. if
+  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)
 
-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:
+* 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.
 
-* using the capability of nmigen (TODO crossref to example) output the module to a yosys ilang (.il) file
+### 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 nassive 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.
+
+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:
+
+* using the capability of nmigen (TODO crossref to example) output the
+  module to a yosys ilang (.il) file
 * in a separate terminal window, run yosys
 * at the yosys prompt type "read_ilang modulename.il"
-* type "show top" and a graphviz window should appear. note that typing 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 reasonably obvious, 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 not tiny when zoomed out, and connections are not total incomprehensible spaghetti, then congratulations, you have well-designed code. If not, then this indicates a need to split the code further into submodules.
+* type "show top" and a graphviz window should appear. note that typing
+  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
+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
+not tiny when zoomed out, and connections are not total incomprehensible
+spaghetti, then congratulations, you have well-designed code. If not,
+then this indicates a need to split the code further into submodules
+and do a bit more work.
 
 The reasons for doing a proper modularisation job are several-fold:
 
-* firstly, we will not be doing a full automated layout-and-hope using alliance/coriolis2, we will be doing leaf-node thru tree node half-automated half-manual layout, finally getting to the floorplan, then revising and iteratively adjusting.
-* secondly, examining modules at the gate level (or close to it) is just good practice.  poor design creeps in by *not* knowing what the tools are actually doing.
-* thirdly, unit testing, particularly formal proofs, is far easier on small sections of code.
+* firstly, we will not be doing a full automated layout-and-hope
+  using alliance/coriolis2, we will be doing leaf-node thru tree node
+  half-automated half-manual layout, finally getting to the floorplan,
+  then revising and iteratively adjusting.
+* secondly, examining modules at the gate level (or close to it) is just
+  good practice.  poor design creeps in by *not* knowing what the tools
+  are actually doing (word to experienced developers: yes, we know that
+  the yosys graph != final netlist).
+* 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.
+
+This can be quite overwhelming to a beginner developer, especially one
+used to writing scripts of only 100 lines in length.
+
+Thanks to Samuel Falvo we learned that writing unit tests as a formal
+proof is not only shorter, it's also far more readable and also, if
+written properly, provides 100% coverage of corner-cases that would
+otherwise be overlooked or require tens to hundreds of thousands of
+tests to be run.
+
+No this is not a joke or even remotely hypothetical, this is an actual
+real-world problem.
+
+The ieee754fpu requires several hundreds of thousands of tests to be
+run (currently needing several days to run them all), and even then we
+cannot be absolutely certain that all possible combinations of input have
+been tested.  With 2^128 permutations to try with 2 64 bit FP numbers
+it is simply impossible to even try.
+
+This is where formal proofs come into play.
+
+Samuel illustrated to us that "ordinary" unit tests can then be written
+to *augment* the formal ones, serving the purpose of illustrating how
+to use the module, more than anything.
+
+However it is appreciated that writing formal proofs is a bit of a
+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.
+* There exist several nmigen examples which are also executable
+  <https://github.com/m-labs/nmigen/tree/master/examples/> exactly as
+  described in the above tutorial (python3 filename.py -h)
+