This wiki describes the Ubuntu Kernel Stable Release Updates Maintenance Procedure with an example.
The following steps in brief shall help in SRU maintenance:
Say you are releasing a stable update for 184.108.40.206
- Get the source of the upstream stable releases
git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.31.y.git
Note: If you got a clone of Linus tree somewhere local, you should use --reference to minimize the space required for this new repository.
- See what has changed since the last release. Since, in this document we talk about the 220.127.116.11 Ubuntu SRU kernel we do the following:
git log v18.104.22.168..v22.214.171.124
v126.96.36.199 and v188.8.131.52 are tags applied to the git tree. We are trying to find the git log between these tags. Should v184.108.40.206 be the latest update, it does not need to be specified. So the following is giving the same result:
git log v220.127.116.11..
Now that you have a listing of the patches, you need to get the actual patches.
git format-patch [-s] [-o <dir>] v18.104.22.168..v22.214.171.124
The -s adds your Signed-off-by: to every patch that is generated and the -o lets you select the directory where those patches are stored. The default is the current directory. You can of course use any convenient location to store your patches generated. These patches will be numbered as 0001* and so on.
- Now start looking at the patch from 0001* .. look at the code and review it. You could use the following as a guideline for your review:
- why is the patch applied ?
- could you categorize it as follows: (please change/add any other category you feel more appropriate)
- Look in kernel bugzilla for bugs which are mentioned in the patch description. Read the comments by other kernel developers to get more insight in the development of a patch. If the patch is a regression, look at the previous patch which introduced the regression. look at user comments.
- Sometimes when you are reviewing the patchset in 126.96.36.199 for the Ubuntu kernel, the upstream review of 188.8.131.52/12 may be over. Look out for this. Look if any regression was introduced in 184.108.40.206 and is fixed in the forward releases. If so, withhold this patch and apply it along with the fix. Comment this in your review mail.
Look at launchpad for bugs which this patch might fix. Note this bug number and its link. Note that you could look at launchpad bugs with their associated upstream bug number too. Have a look at https://bugs.edge.launchpad.net/bugs/bugtrackers/linux-kernel-bugs and sort it on the upstream bug number. Then you could see if the upstream bug number is linked against a launchpad bug.
- Now that your personal review of the stable release patches is over, you need to send it across to other people on the Ubuntu kernel list, so that they can review it and ack it or give further insight. Before doing this do the following:
Open a bug on Launchpad indicating that 220.127.116.11 (in our example) has been released upstream and you would like to see these updates in Ubuntu release-name (Karmic in this case). Look at an example tracking bug. I looked at the one Leann made. Here is a link: https://bugs.edge.launchpad.net/ubuntu/karmic/+source/linux/+bug/496816 Make a similar bug that tracks the updates. This bug is called the "tracking bug" for an update. The tracking bug should list the patches that were introduced by the upstream stable kernel release. This should be the output of:
git log --reverse --pretty=%s v18.104.22.168..v22.214.171.124You should also mention what launchpad bugs this update might fix. Also if you are reverting any patch in favor of an upstream patch, then mention this in the tracking bug on launchpad. However this you will be able to find out only when you apply the patches. The patches can be applied only after the next step. So you could update this part later.
Now you need to include this bug link in all your patches. This indicates, that you are applying this patch to the Ubuntu kernel for resolving this launchpad bug. This can be done by using the maint-modify-patch written by Stefan (git://kernel.ubuntu.com/smb/maint-tools.git).
You configure the maint-tools by looking at the maint-tools/doc/example-maintscript.cfg. Copy the file to $HOME/.maintscripts.cfg. Open the new file and create an alias with your name and replace the signer: field with your alias. Finally add the path to the script to the PATH variable in .bashrc to make it available from any place (this has to be done only once). Then
cd <dir-where-you-have-your-patches> maint-modify-patch -b <bugnumber> *.patch
- You now need to sign these patches with your name. This is also done using the maintools.
maint-modify-patch -s *.patch
Alternatively you could sign the patches when you acquire them (see git format-patch).
Now open the patches and verify that the correct bug link is inserted (should start with BugLink:) and that all patches are signed by your name appropriately.
Besides the buglink above, you also should add the link to any bug on launchpad that the patch resolves in particular. Use the maintools to do so. Again verify the BugLink:
- Now you are ready to apply these patches. So create a new branch on which you will apply these patches.
git fetch git checkout -b stable-126.96.36.199 origin/master git am <location where your patches are>/00*.patch
This will apply all the patches that you created using git format. If the above command fails, then most probably the reason is that you already had a similar patch in your Ubuntu tree before. Identify why the patch was already present in your Ubuntu tree. Was it because of any security reasons or was it a [SAUCE] patch that enabled hardware or one which was accepted upstream but not yet released as a part of stable updates? Unless its a security patch, revert the existing patch in favor of the upstream patch. The idea is that you want the most updated patch and the upstream patch is most likely to be that one. The security patch is however not reverted. You keep the already existing security patch and skip the upstream patch. However you need to mention this in your review email. Also mention this revert or skip in your tracking bug on launchpad.
- If the patch has been applied by a security release, simply skip over that patch with
git am --skip
If we were carrying that patch as a [SAUCE] patch or have been pulled it to resolve a bug report, we revert the old patch and replace it with the upstream patch. First find the commit SHA-ID of the previously applied patch, then revert it with
git revert -e -s <commit-id>
When you revert a patch in favor of an upstream patch note this in the git message for revert - "This patch is reverted in favor of an upstream patch in stable update 2.6.31.<y>". When the revert is done, apply the patch from upstream. As the git am failed, it is still in .git/rebase-apply.
patch -p1 <.git/rebase-apply/patch
Add the files changed by the patch with git add (to find out which files have changed git status can be used) and then resume applying it (this also will proceed with the remaining patches) with
git am --resolved
- If the patch has been applied by a security release, simply skip over that patch with
Now compile the branch with all these patches applied. (You can compile you kernel using Stefan's buildscripts for remote compiling). See if any patch needs to bump the ABI. Revert that patch, see if the kernel compiles. If so, then you have identified which patch needs to bump the ABI. Note this patch. Mention this patch and ABI bump, in your review email. The ABI bump can be done as follows:
Up to Hardy (or before abstracted debian)
Edit debian/changelog and increment the ABI number (e.g. 188.8.131.52.2 becomes 184.108.40.206.2). Then
touch debian/control.stub.in fakeroot debian/rules clean git add debian git commit -s -F debian/commit-templates/bumabi
- For newer releases (with abstracted debian) Edit debian.master/changelog and increment the ABI by 1. (e.g. 2.6.31-18.56 would become 2.6.31-19.56). Then
git add debian.master/changelog git commit -s -F debian/commit-templates/bumpabi fakeroot debian/rules cleanThe clean step here ensures that all generated files are updated.
Now that your patches are applied, you need to either commit these changes if you have the permission or post them to your public repository. As an example: if you have a branch name stable-220.127.116.11 and you want to push it to your public personal repository on http://kernel.ubuntu.com, then one trick to do the push in a quick and easier manner is described below with an example. Say you always want to push your repositories to kernel.ubuntu.com:/srv/kernel.ubuntu.com/git/<username>ubuntu-karmic.git and say you want to push a branch named stable-18.104.22.168 then do this:
git remote add <local name> <username>@kernel.ubuntu.com:/srv/kernel.ubuntu.com/git/<username>/ubuntu-karmic.git
You do this once and this creates a remote entry that allows you to refer to that repository by the name you choose (for example mykarmic). Then you can push your working branch to it with the following command:
git push mykarmic +stable-22.214.171.124
You do this every time you want to update your remote repository with your local branch. The + allows you to completely replace the current state of your remote branch. Without that, only fast-forward changes are allowed.
Now write an email to email@example.com indicating the tracking bug number and the SRU update number for your Ubuntu kernel and release so and so. Indicate what bugs on launchpad this update might fix. Also indicate the location to the public repository where your branch is kept. Also indicate the location of the upstream changelog and patchset for this stable update. This shall generally be:
git log --reverse --pretty=short v126.96.36.199..v188.8.131.52After every patch description, insert your comments. It helps other people to have then categorized, though that is not strictly required. The format is more or less free-form, just keep in mind that other people will read over those and want to understand/grasp the information quickly. An example comment section could be:
Type (or Category): Memory corruption Limits the end condition of a loop to stay within array limits.In general the comment should be a one line description of what the patch does. Whether any patch was reverted for applying this patch. Whether this patch causes regression, the fix of which is released in a forward stable release, due to which we shall apply the patch with that fix. Whether this patch is an ABI bumper.
Thats it !.. press the send button ! and you are good to go