coreboot Lesson 2: Submitting a patch to coreboot.org

Part 1: Setting up an account at coreboot.org

If you already have an account, skip to Part 2.

Otherwise, go to https://review.coreboot.org in your preferred web browser. Select Register in the upper right corner.

Select the appropriate sign-in. For example, if you have a Google account, select Google OAuth2 (gerrit-oauth-provider plugin)”.Note: Your username for the account will be the username of the account you used to sign-in with. (ex. your Google username).

Part 2a: Set up RSA Private/Public Key

If you prefer to use an HTTP password instead, skip to Part 2b.

For the most up-to-date instructions on how to set up SSH keys with Gerrit go to https://gerrit-documentation.storage.googleapis.com/Documentation/2.14.2/user-upload.html#configure_ssh) and follow the instructions there. Then, skip to Part 3.

Additionally, that section of the Web site provides explanation on starting an ssh-agent, which may be particularly helpful for those who anticipate frequently uploading changes.

If you instead prefer to have review.coreboot.org specific instructions, follow the steps below. Note that this particular section may have the most up-to-date instructions.

If you do not have an RSA key set up on your account already (as is the case with a newly created account), follow the instructions below; otherwise, doing so could overwrite an existing key.

In the upper right corner, select your name and click on Settings. Select SSH Public Keys on the left-hand side.

In a terminal, run “ssh-keygen” and confirm the default path ”.ssh/id_rsa”.

Make a passphrase – remember this phrase. It will be needed whenever you use this RSA Public Key. Note: You might want to use a short password, or forego the password altogether as you will be using it very often.

Open “id_rsa.pub”, copy all contents and paste into the textbox under “Add SSH Public Key” in the https://review.coreboot.org webpage.

Part 2b: Setting up an HTTP Password

Alternatively, instead of using SSH keys, you can use an HTTP password. To do so, after you select your name and click on Settings on the left-hand side, rather than selecting SSH Public Keys, select HTTP Password.

Click Generate Password. This should fill the “Password” box with a password. Copy the password, and add the following to your $HOME/.netrc file:

machine review.coreboot.org login YourUserNameHere password YourPasswordHere

where YourUserNameHere is your username, and YourPasswordHere is the password you just generated.

Part 3: Clone coreboot and configure it for submitting patches

On Gerrit, click on the Browse tab in the upper left corner and select Repositories. From the listing, select the “coreboot” repo. You may have to click the next page arrow at the bottom a few times to find it.

If you are using SSH keys, select ssh from the tabs under “Project coreboot” and run the clone with commit-msg hook command that’s provided. This should prompt you for your id_rsa passphrase, if you previously set one.

If you are using HTTP, instead, select http from the tabs under “Project coreboot” and run the command that appears

After it finishes cloning, “cd coreboot” will take you into the local git repository. Run “make gitconfig” to set up the hooks and configurations. For example, you will be asked to run the following commands to set your username and email.

git config --global user.name "Your Name"
git config --global user.email "Your Email"

Part 4: Submit a commit

An easy first commit to make is fixing existing checkpatch errors and warnings in the source files. To see errors that are already present, build the files in the repository by running ‘make lint’ in the coreboot directory. Alternatively, if you want to run ‘make lint’ on a specific directory, run:

for file in $(git ls-files | grep src/amd/quadcore); do \
util/lint/checkpatch.pl --file $file --terse; done

where is the filepath of the directory (ex. src/cpu/amd/car).

Any changes made to files under the src directory are made locally, and can be submitted for review.

Once you finish making your desired changes, use the command line to stage and submit your changes. An alternative and potentially easier way to stage and submit commits is to use git cola, a graphical user interface for git. For instructions on how to do so, skip to Part 4b.

Part 4a: Using the command line to stage and submit a commit

To use the command line to stage a commit, run

git add <filename>

where filename is the name of your file.

To commit the change, run

git commit -s

Note: The -s adds a signed-off-by line by the committer. Your commit should be signed off with your name and email (i.e. Your Name , based on what you set with git config earlier).

Running git commit first checks for any errors and warnings using lint. If there are any, you must go back and fix them before submitting your commit. You can do so by making the necessary changes, and then staging your commit again.

When there are no errors or warnings, your default text editor will open. This is where you will write your commit message.

The first line of your commit message is your commit summary. This is a brief one-line description of what you changed in the files using the template below:

: Short description ex. cpu/amd/pi/00630F01: Fix checkpatch warnings and errors Note: It is good practice to use present tense in your descriptions and do not punctuate your summary.

Then hit Enter. The next paragraph should be a more in-depth explanation of the changes you’ve made to the files. Again, it is good practice to use present tense. ex. Fix space prohibited between function name and open parenthesis, line over 80 characters, unnecessary braces for single statement blocks, space required before open brace errors and warnings.

When you have finished writing your commit message, save and exit the text editor. You have finished committing your change. If, after submitting your commit, you wish to make changes to it, running “git commit –amend” allows you to take back your commit and amend it.

When you are done with your commit, run ‘git push’ to push your commit to coreboot.org. Note: To submit as a draft, use ‘git push origin HEAD:refs/drafts/master’ Submitting as a draft means that your commit will be on coreboot.org, but is only visible to those you add as reviewers.

Part 4b: Using git cola to stage and submit a commit

If git cola is not installed on your machine, see https://git-cola.github.io/downloads.html for download instructions.

After making some edits to src files, rather than run “git add,” run ‘git cola’ from the command line. You should see all of the files edited under “Modified”.

In the textbox labeled “Commit summary” provide a brief one-line description of what you changed in the files according to the template below:

: Short description ex. cpu/amd/pi/00630F01: Fix checkpatch warnings and errors Note: It is good practice to use present tense in your descriptions and do not punctuate your short description.

In the larger text box labeled ‘Extended description...’ provide a more in-depth explanation of the changes you’ve made to the files. Again, it is good practice to use present tense. ex. Fix space prohibited between function name and open parenthesis, line over 80 characters, unnecessary braces for single statement blocks, space required before open brace errors and warnings.

Then press Enter two times to move the cursor to below your description. To the left of the text boxes, there is an icon with an downward arrow. Press the arrow and select “Sign Off.” Make sure that you are signing off with your name and email (i.e. Your Name , based on what you set with git config earlier).

Now, review each of your changes and mark either individual changes or an entire file as Ready to Commit by marking it as ‘Staged’. To do this, select one file from the ‘Modified’ list. If you only want to submit particular changes from each file, then highlight the red and green lines for your changes, right click and select ‘Stage Selected Lines’. Alternatively, if an entire file is ready to be committed, just double click on the file under ‘Modified’ and it will be marked as Staged.

Once the descriptions are done and all the edits you would like to commit have been staged, press ‘Commit’ on the right of the text boxes.

If the commit fails due to persisting errors, a text box will appear showing the errors. You can correct these errors within ‘git cola’ by right-clicking on the file in which the error occurred and selecting ‘Launch Diff Tool’. Make necessary corrections, close the Diff Tool and ‘Stage’ the corrected file again. It might be necessary to refresh ‘git cola’ in order for the file to be shown under ‘Modified’ again. Note: Be sure to add any other changes that haven’t already been explained in the extended description.

When ready, select ‘Commit’ again. Once all errors have been satisfied and the commit succeeds, move to the command line and run ‘git push’. Note: To submit as a draft, use ‘git push origin HEAD:refs/drafts/master’ Submitting as a draft means that your commit will be on coreboot.org, but is only visible to those you add as reviewers.

Part 5: Getting your commit reviewed

Your commits can now be seen on review.coreboot.org if you select “Your” and click on “Changes” and can be reviewed by others. Your code will first be reviewed by build bot (Jenkins), which will either give you a warning or verify a successful build; if so, your commit will receive a +1. Other users may also give your commit +1. For a commit to be merged, it needs to receive a +2.Note: A +1 and a +1 does not make a +2. Only certain users can give a +2.

Part 6 (optional): bash-git-prompt

To help make it easier to understand the state of the git repository without running ‘git status’ or ‘git log’, there is a way to make the command line show the status of the repository at every point. This is through bash-git-prompt.

Instructions for installing this are found at: https://github.com/magicmonty/bash-git-prompt Note: Feel free to search for different versions of git prompt, as this one is specific to bash.

Alternatively, follow the instructions below: Run the following two commands in the command line:

cd
git clone https://github.com/magicmonty/bash-git-prompt.git .bash-git-prompt --depth=1

Note: cd will change your directory to your home directory, so the git clone command will be run there.

Finally, open the ~/.bashrc file and append the following two lines:

GIT_PROMPT_ONLY_IN_REPO=1
source ~/.bash-git-prompt/gitprompt.sh

Now, whenever you are in a git repository, it will continuously display its state.

There also are additional configurations that you can change depending on your preferences. If you wish to do so, look at the “All configs for .bashrc” section on https://github.com/magicmonty/bash-git-prompt. Listed in that section are various lines that you can copy, uncomment and add to your .bashrc file to change the configurations. Example configurations include avoid fetching remote status, and supporting versions of Git older than 1.7.10.

Appendix: Miscellaneous Advice

Updating a commit after running git push:

Suppose you would like to update a commit that has already been pushed to the remote repository. If the commit you wish to update is the most recent commit you have made, after making your desired changes, stage the files (either using git add or in git cola), and amend the commit. To do so, if you are using the command line, run “git commit –amend.” If you are using git cola, click on the gear icon located on the upper left side under Commit and select Amend Last Commit in the drop down menu. Then, stage the files you have changed, commit the changes, and run git push to push the changes to the remote repository. Your change should be reflected in Gerrit as a new patch set.

If, however, the commit you wish to update is not the most recent commit you have made, you will first need to checkout that commit. To do so, find the URL of the commit on https://review.coreboot.org and go to that page; if the commit is one that you previously pushed, it can be found by selecting My and then Changes in the upper left corner. To checkout this commit, in the upper right corner, click on Download, and copy the command listed next to checkout by clicking Copy to clipboard. Then, run the copied command in your coreboot repository. Now, the last commit should be the most recent commit to that patch; to update it, make your desired changes, stage the files, then amend and push the commit using the instructions in the above paragraph.