On 5/2/19 2:33 PM, sean.brogan via groups.io wrote:
Brian,

I would really like to hear about the challenges your team faced and issues that caused those solutions to be unworkable.  Project Mu has and continues to invest a lot in testing capabilities, build automation, and finding ways to improve quality that scale.


Our products depend on a reference BIOS tree provided to us by a major processor vendor. That tree includes portions of Edk2, plus numerous proprietary additions. Each new platform starts with a new drop of vendor code. They provide additional drops throughout the platform's life. In the past these were distributed as zip files, but more recently they have transitioned to git. We end up having to make extensive changes to their code to port it to our platform. In addition, we maintain internally several packages of code used on all our platforms, designed to be platform-independent, plus a platform-dependent package which is intended to be modified for each platform.

When we first started using git, we looked for a way to share our all-platform code among platforms, and move our platform-dependent code easily to new platforms, while making it easy to integrate new drops from our vendor. We considered using git submodules, but decided that would be too awkward. Modifying code in a submodule involves committing in the submodule, then committing in the module containing it. This seemed like too much trouble for our developers, who were all new to git. Plus, it didn't interact well at all with our internal bug tracking system. Basically, there was no good way to tie commits in various sub- and super-modules together in a straightforward, trackable way.

We tried a package called gitslave (http://gitslave.sourceforge.net/), which automates running git commands across a super-repo and various sub-repos, with some sugar for aggregating the results into a readable whole. It's a bit more transparent than submodules. But at the end of the day, you're still trying to coordinate multiple git repositories. We gave it a try for a month or two, but having to manage multiple repositories for day-to-day work, and the lack of a single commit history spanning the entire tree doomed that scheme. Developers rebelled.

Ever since, we've used a single git repo per platform. We keep the vendor code in a "base" branch, which we update as they provide drops, then merge into our master branch. When we start a new platform, we use git filter-branch to extract our all-platform and platform-dependent code into a new branch, which we move to the new platform's repo and merge into master. It's possible to re-extract the code if we need to pick up updates. This doesn't provide total flexibility... for instance, backporting a fix in our all-platform code back to a previous platform involves manual cherrypicking. But for day-to-day development, it lets us work in a single git tree, with a bisectable history, working git-blame, commit IDs which tie directly to our bug tracker, and no external tooling. It's a bit of a pain to merge a new drop (shell scripts are our friends), but we're optimizing for ease of local development. That seems like the best use of our resources.

So I'm leery of any scheme which involves multiple repos managed by an external tool. It sounds like a difficult way to do day-to-day development. If Edk2 does move to split repos, we could filter-branch and merge them all together into a single branch for internal use, I suppose. But that does make it harder to push fixes upstream. (Not that we end up doing a lot of that... we're not developing an open-source BIOS, just making use of open-source upstream components. So our use case is quite a bit different from Laszlo's.) We're also generally focusing on one platform at a time, not trying to update shared code across many at once. So our use case may be different from Sean's.

This got rather long... I hope it helps explain where we're coming from.
--
Brian J. Johnson
Enterprise X86 Lab
Hewlett Packard Enterprise
brian.john...@hpe.com

-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.

View/Reply Online (#39961): https://edk2.groups.io/g/devel/message/39961
Mute This Topic: https://groups.io/mt/31242794/21656
Group Owner: devel+ow...@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub  [arch...@mail-archive.com]
-=-=-=-=-=-=-=-=-=-=-=-

Reply via email to