如何跨多个 AOSP 项目创建补丁？

Question

The process documented here is for making a change to a single project (aka git repo).

But the change I have (implement a single new piece of functionality) spans multiple projects, is it possible to create a single patch to do this or does this need to be broken up into seperate interdependant patches?

Answer 1

I think you should divide your patch into patches for each project. Here is the logic why I think this. Each Android project has it's own .git directory, ie these projects are in separate git repositories. Repo tool is just an addition over git commands, ie it does not provide you with new functionality. Thus, you cannot create a patch that will span across the projects (because they are not connected). Therefore, you need to divide your patch into separate patches for each AOSP project that is affected by your new functionality.

Answer 2

To create a project wide diff, use this command: repo diff > /path/to/store/patch/all-changes.diff

Next, one can also use repo forall -p -c git status to check the status of each project.

repo forall -p -c git diff will show diff for each project.

Even I am trying to figure out how to generate patches for individual projects. However, if you understand the AOSP source, all the projects are coming from aosp_root/.repo/manifests/default.xml

If you try something like repo forall -p -c git diff > /path/to/patch/change.diff , this file will contain all the patches. I still haven't figured out how to extract the -p part, which prints the project name (Usually is a relative path inside the aosp_root), and convert it into a patch name.

However, these things are really not hard to in a bash environment with some scripting. Heck, I think repo is also open source, meaning you could even modify it youself!

If you take a look at this manifest, you should notice that the projects are interpreted same way as git repo projects which are easy to clone and reproduce the patches for. Though very similar to git, AOSP folder structure varies from device to device, SOM to SOM. It makes it a little harder to actually create individual projects due to path and other dissimilarities.

One thing that I am familiar with is using a tool like splitpatch on linux machines to split out the patches. However, this tool like others, will find splitting AOSP patches since many files have the same name, for example, if you change Android.mk across multiple projects, the patch splitter finds it hard to understand this structure, so it thinks that the same file was modified over and over.

If you refer the AOSP documentation, for anything, you'll find a good amount of information. Now you will need to use non-traditional search techniques to actually find most of them. The AOSP Documentation that Google provides on the web is not sufficient to understand everything. It's just a starting point.

The actual documentation is found inside the specific project. If you look at the Readme files under that project, or the docs/ folder, then you might find something more relevant.

It's easy to say that it's not well documented, but actually the problem is in exposure and organization. Documentation is available abundantly, finding it often is the problem.