Grabbing kernel patches from mailing lists and the internet

| categories: kernel, fedora

The kernel community runs on mailing lists. All change sets end up through one mailing list or another. The mailing list is great for reviewing and reading changes but eventually the patches need to be tested or pulled into a tree, for testing or release. Every developer comes up with a workflow that work for them. Greg KH has a screencast showing what he does to apply patches to the stable tree. My workflow is simpler and less optimized:

  • Save the patch from my e-mail client (I mostly use thunderbird)
  • Checkout appropriate branch in my kernel tree
  • $ git am <patch path>

git am takes care of most of the hard work of putting the patch into git. Generally the tree I'm working off of is a local copy of the kernel.org tree. To generate a patch that can be brought over to the Fedora kerne pkg-git

  • $ git format-patch -1 HEAD

git format-patch again takes care of generating a nice patch file. This is also what I use for generating patches that are already in a git tree. I'll often add the tree as a remote to my system:

  • $ git remote add new-repo-name git://url-to-repo
  • $ git fetch new-repo-name
  • $ git log find commit hash
  • $ git format-patch -1 <hash>

Some git web versions will also have a patch download option. For kernel.org, https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=<COMMIT HASH> (drop the angle brackets around the commit hash) will show you the a commit on the kernel master branch which should have a patch download link (the commit/?id=<commit hash> trick should work on other cgit sites, again dropping the angle brackets around the hash)

If a patch isn't a git tree and you aren't subscribed to the mailing list, LKML and other spinoffs archive patches through a tool called patchwork. patchwork.kernel.org has archives for LKML and a number of other mailing lists.

The number of patches that come in through the LKML patchwork is the same as LKML (so quite large). patchwork is not great for searching through all patches; it's best if you know which patch you are looking for. The easiest way to find a patch is to use the filter. Right above the list of patch subjects should be a link 'Filters' which should drop down a menu. I've found searching by submitter to be the easiest way to find patches (there's auto completion to help you along). Once you've found the patch subject, the mbox download link will give you a file that can be applied with git am.

Between kernel.org and a few other places, most mailing lists should be covered by patchwork. Some will still slip through the cracks though. At that point, the best option is to find the message on an archive somewhere and look for a link to download the raw message. You can also be brave and copy and paste the message into a file and fix up any whitespace mangling yourself. Once you've done this, you'll understand why maintainers hate getting patches that don't apply or are whitespace damaged.

Again, as I mentioned at the beginning every developer has their own workflow. I'm sure others can find ways to improve this flow. The goal here is to give an idea about how to produce patch files from patches others have made available.