Prof. Sophia Shao
TAs (ASIC): Dima Nikiforov
Department of Electrical Engineering and Computer Science
College of Engineering, University of California, Berkeley
The process of VLSI design is different than developing software, designing analog circuits, and even FPGA-based design. Instead of using a single graphical user interface (GUI) or environment (eg. Eclipse, Cadence Virtuoso, or Xilinx Vivado), VLSI design is done using dozens of command line interface tools on a Linux machine. These tools primarily use text files as their inputs and outputs, and include GUIs mainly for only visualization, rather than design. Therefore, familiarity with Linux, text manipulation, and scripting is required to successfully complete the labs this semester.
The goal of this lab is to introduce some basic techniques needed to use the computer aided design (CAD) tools that are taught in this class. Mastering the topics in this lab will help you save hours of time in later labs and make you a much more efficient chip designer. While you go through this lab, focus on how these techniques will allow you to automate tasks and improve your efficiency. Chip design requires plenty of iteration, so being able to perform trials and identify errors quickly is key to success.
This lab, like all labs will be turned in electronically using Gradescope. Please upload a pdf document with the answers to the six questions in the lab.
You are required to get an EECS instructional account to login to the workstations in the lab, since you will be doing all your work on these machines (whether you're working remotely or in-person). This can be done by using WebAcct here: http://inst.eecs.berkeley.edu/webacct.
Once you login using your CalNet ID, you can click on 'Get a new account' in the eecs151 row. Once the account has been created, you can email your class account form to yourself to have a record of your account information. You can follow the instructions on the emailed form to change your Linux password with ssh update.eecs.berkeley.edu and following the prompts.
The servers used for this class are primarily eda-[1-11].eecs.berkeley.edu. You may also use the c111-[1-17].eecs.berkeley.edu machines
(which are physically located in Cory 111/117), although those will be shared with the FPGA lab. You can access all of these machines remotely through SSH.
It is important that you can remotely access the instructional servers. There are two convenient ways to remotely access our
lab machines: SSH (Secure SHell) and X2Go.
First, select a machine. The range of accessible machines are eda-X, where X is a number from 1 to 11,
and c111-X, where X is a number from 1 to 17. The fully qualified DNS name (FQDN) of
your machine is then eda-X.eecs.berkeley.edu or c111-X.eecs.berkeley.edu. For example,
if you select machine eda-8, the FQDN would be eda-8.eecs.berkeley.edu.
You can use any lab machine, but our lab machines aren’t very powerful; if everyone
uses the same one, everyone will find that their jobs perform poorly. ASIC design tools are resource
intensive and will not run well when there are too many simultaneous users on these machines. We
recommend that every time you want to log into a machine, examine its load on https://hivemind.eecs.berkeley.edu/
for the eda-X machines, or using top when you log in. If it is heavily loaded, consider
using a different machine. If you also notice other eecs151 users with jobs consuming excessive
resources, do feel free to reach out to the GSIs about it.
Next, note your instructional class acccount name - the one that looks like eecs151-YYY, for example
eecs151-abc. This is the account you created at the start of this lab.
SSH is the de facto remote terminal tool for Linux and BSD systems (which includes macOS). It lets you login to a text console from anywhere (as long as you have network connectivity). SSH also comes as a standard utility in almost all Linux and BSD systems. If you’re using Linux or BSD, you should be able to access your workstation through SSH by running:
In our examples, this would be:
The SSH protocol also enables file transfer between your local and lab machines via the sftp and
scp utilities. WARNING: please only transfer files needed for your reports and nothing else, particularly files relating to CAD tool commnads or process technologies!!!
The classic and most lightweight way to use SSH on Windows is PuTTY (https://www.putty.org/). Download it and login with the FQDN above as the Host and your instructional account username. You can also use WinSCP (winscp.net) for file transfer over SSH. Advanced users may wish to install Windows Subsystem for Linux (https://docs.microsoft.com/en-us/windows/wsl/install-win10, Windows 10 build 16215 or later) or Cygwin (cygwin.com) and use SSH, SFTP, and SCP through there.
Because all your work will be done remotely, we recommend that you utilize SSH session management tools and that all terminal-based work be done over SSH. This would allow your remote terminal sessions to remain active even if your SSH session disconnects, intentionally or not. The two most common session managers are tmux and screen. These run persistently on the remote workstation, are highly customizable, and can greatly improve your productivity. Here are some good tmux and screen tutorials:
- https://www.hamvocke.com/blog/a-quick-and-easy-guide-to-tmux/
- https://www.rackaid.com/blog/linux-screen-tutorial-and-how-to/
For situations in which you need a graphical interface (waveform debugging, layout viewing, etc.), you should use X2Go. This is a faster and more reliable alternative to more traditional XForwarding over SSH. X2Go is also recommended because it connects to a persistent graphical desktop environment, which continues running even if your internet connection drops. Download the X2Go client for your platform from the website: https://wiki.x2go.org/doku.php/download:start.
Note: MacOS sometimes blocks the X2Go download/install, if it does follow the directions here: https://support.apple.com/en-us/HT202491.
To use X2Go, you need to create a new session (look under the Session menu). Give the session any name, it doesn’t matter, but set the Host field to the FQDN of your lab machine and the User field to your instructional account username. For “Session type”, select “GNOME”. Here’s an example from macOS:
After you login to one of these servers, you are now ready to start the lab. You have a limited amount of space in your home directory, so we recommend completing work in the /scratch/ directory, and then copying any important results to your home directory.
To begin, get the lab files by typing the following commands:
mkdir /scratch/<your-eecs-username>
cd /scratch/<your-eecs-username>
git clone /home/ff/eecs151/labs/lab1
cd lab1You will need to learn how to use Linux so that you can understand what programs are running on the server, manipulate files, launch programs, and debug problems. Please read through the tutorial here: http://linuxcommand.org/lc3_learning_the_shell.php
To use the CAD tools in this class, you will need to load the class environment. All of the tools are already installed on the network filesystem, but by default users do not have the tools in their path. Try locating a program that is already installed (vim) and another which is not (innovus) by default:
which vim
which innovusThe vim program has been installed in: /usr/bin/vim. If you show the contents of /usr/bin,
you will notice that you can launch any of programs by typing their filename. This is because
/usr/bin is in the environment variable $PATH, which contains different directories to search in a
colon-separated list.
echo $PATHTo be able to access the CAD tools, you will need to append to their location to the $PATH variable:
source /home/ff/eecs151/tutorials/eecs151.bashrc
echo $PATH
which innovusFor 1-6 below, submit the command/keystrokes needed to generate the desired result. For 1-4, try generating only the desired result (no extraneous info).
- List the 5 most recently modified items in
/usr/bin - What directory is
gitinstalled in? - Show the hidden files in your lab directory (the one you cloned from
/home/ff/eecs151/labs/lab1 - What version of Vim is installed? Describe how you figured this out.
- Copy the files in this lab to
/scratchand then delete it. - Run
ping www.google.com, suspend it, then kill the process. Then run it in the background, report its PID, then kill the process. - Run
topand report the average CPU load, the highest CPU job, and the amount of memory used (just report the results for this question; you don't need to supply the command/how you got it).
There are a few miscellaneous commands to analyze disk usage on the servers.
du -ch --max-depth=1 .
df -HFinally, your instructional accounts have disk usage quotas. Find out how much you are allocated and how much you are using:
quota -sBy default, you should be using the Bash shell (these labs are designed for Bash, not Csh). The Bash Guide (guide.bash.academy) is a great resource for users at all levels of Bash profiency.
Much of the time you will spend designing chips will be writing scripts in a text editor. Therefore becoming proficient at editing text is a vital skill. Unlike Java or C programming, there is no integrated development environment (IDE) for writing these scripts. However, many of the advantages of IDE’s can be obtained by using the proper editor. In this class, we will be using either Vim or Emacs. Editors such as gedit or nano are not allowed.
If you have never used Vim, please follow the tutorial here: http://www.openvim.com/tutorial.html (If you would prefer to learn Emacs, you can read http://www.gnu.org/software/emacs/tour/ and run the Emacs built-in tutorial with Ctrl-h followed by t). Feel free to search for other resources online to learn more.
For each task below, describe the keys you need to press to accomplish the action in the file force_regs.ucli.
- Delete 5 lines
- Search for the text
clock - Replace the text
dutwithdevice_under_test - Jump to the end of the file
- Go to line 42
- Reload the file (in case it was modified in another window)
- Save and exit
While Vim is a powerful editor and ubiquitous on Linux environments, there are other alternatives that might be more suitable for different use cases. A modern graphical text editor is Visual Studio Code, which supports editing text files through an SSH session. As Visual Studio Code renders text on the client machine, it can be useful for students with high latency or irregular internet connections as in such environments X2Go or Vim in SSH can feel unresponsive. To set up Visual Studio Code for remote development, please follow the tutorial here: https://code.visualstudio.com/docs/remote/ssh-tutorial
Regular expressions allow you to perform complex ’Search’ or ’Search and Replace’ operations. Please work through the tutorial here: http://regexone.com
Regular expressions can be used from many different programs: Vim, Emacs, grep, sed, Python, etc. From the command line, use grep to search, and sed to search and replace.
Unfortunately, deciding what characters needs to be escaped can be somewhat confusing. For
example, to find all instances of dcdc_unit_cell_x, where x is a single digit number, using grep:
grep "unit_cell_[0-9]\{1\}\." force_regs.ucliAnd you can do the same search in Vim:
vim force_regs.ucli
/unit_cell_[0-9]\{1\}\.Notice how you need to be careful what characters get escaped (the [ is not escaped but { is). Now
imagine we want to add a leading 0 to all of the single digit numbers. The match string in sed
could be:
sed -e 's/\(unit_cell_\)\([0-9]\{1\}\.\)/\10\2/' force_regs.ucliBoth sed, vim, and grep use ”Basic Regular Expressions” by default. For regular expressions heavy
with special characters, sometimes it makes more sense to assume most characters except a-zA-Z0-9
have special meanings (and they get escaped with only to match them literally). This is called
”Extended Regular Expressions”, and ?+{}() no longer need to be escaped. A great resource
for learning more is http://en.wikipedia.org/wiki/Regular_expression#POSIX_basic_and_extended. In Vim, you can do this with \v:
:%s/\v(unit_cell_)([0-9]{1}\.)/\10\2/And in sed, you can use the -r flag:
sed -r -e 's/(unit_cell_)([0-9]{1}\.)/\10\2/' force_regs.ucliAnd in grep, you can use the -E flag:
grep -E "unit_cell_[0-9]{1}\." force_regs.uclised and grep can be used for many purposes beyond text search and replace. For example, to find all files in the current directory with filenames that contain a specific text string:
find . | grep ".ucli"Or to delete all lines in a file that contain a string:
sed -e '/reset/d' force_regs.ucliFor each regular expression, provide an answer for both basic and extended mode (sed and sed -r).
You are allowed to use multiple commands to perform each task. Operate on the force_regs.ucli file.
- Change all x's surrounding numbers to angle brackets. For example,
regx15xx79xbecomesreg<15><79>. Hint: remember to enable global subsitution. - Make every number in the file be exactly 3 digits with padded leading zeros (except the last 0 on each line). Eg. line 120/121 should read:
force -deposit rocketTestHarness.dut.Raven003Top_withoutPads.TileWrap.
... .io_tilelink_release_data.sync_w002r.rq002_wptr_regx000x.Q 0
force -deposit rocketTestHarness.dut.Raven003Top_withoutPads.TileWrap.
... .io_tilelink_release_data.fifomem.mem_regx015xx098x.Q 0
A tutorial about file permissions can be found here: http://www.tutorialspoint.com/unix/unix-file-permission.htm
For each task below, please provide the commands that result in the correct permissions being set. Make no assumptions about the file's existing permissions. Operate on the run_always.sh script.
- Change the script to be executable by you and no one else.
- Add permissions for everyone in your group to be able to execute the same script
- Make the script writable by you ane everyone in your group, but unreadable by others
- Change the owner of the file to be
eecs151(Note: you will not be able to execute this command, so just provide the command itself)
Makefiles are a simple way to string together a bunch of different shell tasks in an intelligent manner. This allows someone to automate tasks and save time when doing repetitive tasks since make targets allow for only files that have changed to need to be updated. Please read through the following tutorial here: http://www.cs.colby.edu/maxwell/courses/tutorials/maketutor/ (optional). Further documentation on make can be found here: http://www.gnu.org/software/make/manual/make.html.
Let’s look at a simple makefile to explain a few things about how they work - this is not meant to be anything more than a very brief overview of what a makefile is and how it works. If you look at the Makefile in the provided folder in your favorite text editor, you can see the following lines:
output_name = force_regs.random.ucli
$(output_name): force_regs.ucli
awk 'BEGIN{srand();}{if ($$1 != "") { print $$1,$$2,$$3,int(rand()*2)}}' $< > $@
clean:
rm -f $(output_name)While this may look like a lot of random characters, let us walk through each part of it to see that it really is not that complicated.
Makefiles are generally composed of rules, which tell Make how to execute a set of commands to build a set of targets from a set of dependencies. A rule typically has this structure:
targets: dependencies
commandsIt is very important that indentation in Makefiles are tabs, not spaces. The two rules in the above Makefile have targets which are clean and output name. Here, output name is the name of a variable within the Makefile, which means that it can be overwritten from the command line. This can be done with the following command:
make output_name=foo.txtThis will result in the output being written to foo.txt intstead of force_regs.random.ucli.
Generally, a rule will run everytime that its dependencies have been updated more recently than
its own targets, so by editing/updating the force_regs.ucli file (including via the touch command), you can regenerate the output name target. This is different than a bash script, as you can see in runalways.sh, which will always generate force_regs.random.ucli regardless of whether
force_regs.ucli is updated or not.
Inside the output name target, the awk command has a bunch of $ characters. This is because
in normal awk the variable names are $1, $2, and then in the makefile you have to escape those
variable names to get them to work properly. In Make, the character to do that is $.
The other characters after the awk script are also special characters to make. The $< is the first
dependency of that target, the > simply redirects the output of awk, and the $@ is the name of the
target itself. This allows users to create makefiles that can be reusable, since you are operating on
a dependency and outputting the result into the name of your own target.
- Add a new make rule that will create a file called
foo.txt. Make it also run theoutput_namerule. - Name at least two ways that you could have the makefile regenerate the
output_nametarget after its rule has been run.
Comparing text files is another useful skill. The tools generally behave as black boxes, so comparing output files to prior output files is an important debugging technique.
From the command lines, you can use diff to compare files:
diff force_regs.ucli force_regs.random.ucliYou can also compare the contents of directories (the -q flag will summarize the results to only
show the names of the files that differ, and the -r flag will recurse through subdirectories).
For Vim users, there is a useful built-in diff tool:
vimdiff force_regs.ucli force_regs.random.ucliVersion control systems help track how files change overtime and make it easier for collaborators to work on the same files and share their changes. We use git to distribute the lab files so that bug fixes can easily be incorporated into your files. Please go through the following tutorial: https://try.github.io
Submit the command required to perform the following tasks:
- What is the difference between your current Makefile and the file you started with?
- How do you make a new branch?
- What is the SHA of the version you checked out?
Many of the commands and tools you will use on a daily basis can be customized. This can
dramatically improve your productivity. Some tools (e.g. vim and bash) are customized using “dotfiles,” which are hidden files in your home directory (e.g. .bashrc and .vimrc) that contain a series of commands which set variables, create aliases, or change settings. Try adding the following lines to your .bashrc and restart your session or source
~/.bashrc. Now when you change directories, you no longer need to type ls to show the directory contents.
function cd {
builtin cd "$@" && ls -F
}The following links are useful for learning how to make some common customizations. You should read these but are not required to turn in anything for this section.
- https://www.digitalocean.com/community/tutorials/an-introduction-to-useful-bash-aliases-and-functions
- http://statico.github.io/vim.html
- Submit a written report with all 6 questions answered to Gradescope
This lab is the result of the work of many EECS151/251 GSIs over the years including: Written By:
- Nathan Narevsky (2014, 2017)
- Brian Zimmer (2014) Modified By:
- John Wright (2015,2016)
- Ali Moin (2018)
- Arya Reais-Parsi (2019)
- Cem Yalcin (2019)
- Tan Nguyen (2020)
- Harrison Liew (2020)
- Sean Huang (2021)
- Daniel Grubb, Nayiri Krzysztofowicz, Zhaokai Liu (2021)
- Dima Nikiforov (2022)