- Git guide for Linux wireless users and developers
- Cloning latest wireless-testing
- Get the latest updates
- Review the changes last registered
- To review changes made to wireless drivers
- To review changes made to mac80211
- Hacking on Linux wireless
- Check available branches
- Reviewing changes between commmits
- Merging git branches
- Checkout code as it was from specific commit
- Delete branches
- No need to download more kernel tarballs
- Generate patches
- Fixing patches after review
- Sending patches
Git guide for Linux wireless users and developers
This is a quick git-guide for Linux users and developers with emphasis on Linux wireless. The latest Linux wireless development takes place on John Linville's wireless-testing git tree.
Cloning latest wireless-testing
First, clone the wireless-testing.git tree
git clone git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-testing.git cd wireless-testing
Get the latest updates
You will want to update your local git repository to match what John has last committed. You can do this as follows.
Review the changes last registered
To review changes made to wireless drivers
git log -p drivers/net/wireless/
To review changes made to mac80211
git log -p net/mac80211/
You get the idea.
Hacking on Linux wireless
If you'd like to hack on Linux wireless you can create own branch based on the one you are using. This is so you don't screw your current branch up.
git checkout -b my-fix-for-foo # hack hack hack # To get a diff of your work: git diff > my_changes.diff # Or if you just want to read them: git diff # To revert to the original state of the branch: git checkout -f # If instead you want to commit git commit -a
Check available branches
Suppose you have created a few branches, and just are not sure what you have anymore.
# To view local branches git branch -l # To view all remote branches git branch -r
Reviewing changes between commmits
Suppose you want to get the log and diff between two commits.
# get the SHA of two commits git log # Then get the diff of them, by showing the logs in between git log -p d8a285c8f83f728be2d056e6d4b0909972789d51..9202ec15da36ca060722c363575e0e390d85fb71 # Since SHAs are pretty unique you can just give it a short version # and it will try to match what is right: git log -p d8a28..9202e
Merging git branches
Say you have two local branches, and I want to merge them. If you're on local branch my-latest and I want to merge with local branch my-fix-for-foo, you would do:
git pull . my-fix-for-foo
Checkout code as it was from specific commit
Suppose you want to checkout what the codebase looked like at a specific commit SHA. You can do this with branches.
# Long form: git checkout -b view-commit-foo d8a285c8f83f728be2d056e6d4b0909972789d51 # Or short form: git checkout -b view-commit-foo d8a28
If you are fed up with a branch delete it. You must not be on that branch so go into another one.
git checkout master git branch -D old-branch
No need to download more kernel tarballs
You can simply make your current directory look like a specific tag blessed by Linus (or Linville).
git checkout -b v2.6.27-rc7 v2.6.27-rc7
Say you have 3 commits and you want to send the patches now.
git format-patch --cover-letter -o some-dir d8a285c8f83f728be2d056e6d4b0909972789d51..9202ec15da36ca060722c363575e0e390d85fb71 # this is equivalent to, this is the short form git format-patch --cover-letter -n -o some-dir d8a28..9202e
Where d8a28 was the last commit before you started hacking and 9202e is the current head, meaning the commit ID of your latest commit.
Generating patches for renames
If you are going to rename files you can add "-M" to the arguments to git-format-patch, this way the patches don't generate useless endless removals and adds for a simple rename.
Fixing patches after review
This section tells you how to deal with fixing patches with git after you have sent them out for review or in case you realize you need to go back in history and edit/fix something.
Fixing a patch or commit message
To fix a patch or commit message you have committed you can simply do:
# Edit the file you forgot to add a fix for, and then # tell git (-a option) all the files you have edited # should go into the commit, but that you want it to apply # to the last commit and you also want to review/edit the # commit message git commit -a --amend
If you want to ignore all changes you have pending don't use the "-a" option.
Fixing a series of patches
When you a large set of patches and you are not the maintainer chances are pretty high you'll get feedback and you'll need to respin them. A nice trick to avoid having to use quilt/stgit/etc is to use git to edit the patch back in history and continue then. You can do this with git's rebase.
git rebase -i commit-id-foo
This will let you select which patches you want to edit, once done with editing you will have to add the file you fixed
git add drivers/net/wireless/foo/bar.c
And then amend the commit:
git commit --amend
You can skip the 'git add' part by just using 'git commit -a –amend' but keep in mind this will add into the commit *all* changes in your current diff (git diff).
If you didn't have to remove a commit, let the rebase continue.
git rebase --continue
Keep in mind you will have to edit the patches to deal with conflicts if any were found. To deal with them simply edit the files its complaining about, git add them, and do 'git rebase –continue' once done. The conflicts are marked with a set of "<<<<" in the sections. It'll have part from the original file and the part from the new file. You get to mangle with these to figure out what is the right code.
Annotating new revision
If developers raise issues with your patch you are expected to follow up with another iteration of your patch or series of patches. In your new iteration of patches you should specify that these patches are part of a new iteration. You can do this by specifying the iteration number on the subject. For example, for a second iteration you would use:
You can specify this with git by using an argument to git format-patch:
Removing a commit from a series
If you want to *remove* a commit you can do this trick:
git rebase -i commit-id-foo git checkout commit-id-before-change git rebase --continue
Adding a new commit to the series
If you want to add a new commit to the series simply add the commit using the usual commit procedures. Once you are done continue with the rebase.
Read git-send-email man page. But here is a quick summary for those who just want to get it to work. Keep in mind git send-email is a perl script and is usually shipped separately from git core.
You can install your favorite mailer, one option is to use ssmtp.
Setting up ssmtp
Below is an example config that works with an exchange server, in etc/ssmtp/ssmtp.conf:
email@example.com mailhub=smtp.company.com hostname=smtp.company.com FromLineOverride=YES UseSTARTTLS=YES AuthUser=hacker AuthPass=my-uber-secret-password
Here is an example /etc/ssmtp/revaliases
user can be the username (whoami) on the system.
Once you have your mailer setup and patches in a directory, review them so they are correct. Once all done send them out using:
# Note new versions of git use: git send-email git send-email --no-chain-reply-to --from "Random Developer <firstname.lastname@example.org>" --to email@example.com --cc firstname.lastname@example.org --cc email@example.com some-dir/
Where some-dir is where you stashed your patches. Keep in mind that if you are submitting a series it helps to send an introductory PATCH [0/n] as well, where n is the number of patches you want to send. You can add this to the git-send-email queue easily using –cover-letter when generating patches using git-format-patch. Be sure to edit the patch 0000-foo then. git-send-email will pick it up when you specify the directory