Re: [git pull] drm-next
On Mon, 30 Mar 2009, Dave Airlie wrote: > > > > - Don't merge upstream code at random points. > > > >You should _never_ pull my tree at random points (this was my biggest > >issue with early git users - many developers would just pull my current > >random tree-of-the-day into their development trees). It makes your > >tree just a random mess of random development. Don't do it! > > > >And, in fact, preferably you don't pull my tree at ALL, since nothing > >in my tree should be relevant to the development work _you_ do. > >Sometimes you have to (in order to solve some particularly nasty > >dependency issue), but it should be a very rare and special thing, and > >you should think very hard about it. > > The only case I can think off here, is when I send a tree of bug fixes to > your tree during -rc and I want to make sure the drm-next tree is tested > with those fixes applied to it. I would actually prefer that in this case - especially if things merge cleanly and automatically - you still aim to not merge with me in your development branch. But the "test teh merged state" is obviously a real issue, and it happens at other times than just during the -rc time. In fact, it happens most commonly long before you even want to send me any pull requests, simply because the merge window hasn't even opened yet. So what's the solution? You want to merge for testing, yet I don't want to see random merges of the day in the development tree when I pull? I suspect you can already see the solution coming when I put it that way: the best way is to simply create a test-branch, and do the merge there, and use _that_ branch for testing and for (for example) sending off to the linux-next repository which will combine it with yet other test branches. But note: none of these rules should be absolutely black-and-white. Nothing in life ever is. Sometimes merging with my tree is simply the best option. If it's not your normal mode of operation, but an option in your toolbox that you end up using when everything else is just too painful, go ahead. Git does allow people to do many different things, and solve problems different ways. I just want all the regular workflows to be "good practice", but then if you have to occasionally break the rules to solve some odd problem, go ahead and break the rules (and tell people why you did it that way this time). > Thanks for all this, its quite clear now, I should clean this mail up and > put it into the kernel documentation. Hey, good idea. We have some of that, but if you found the email useful, do feel free to turn it into real documentation. Linus -- -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: [git pull] drm-next
>
> I want clean history, but that really means (a) clean and (b) history.
>
> People can (and probably should) rebase their _private_ trees (their own
> work). That's a _cleanup_. But never other peoples code. That's a "destroy
> history"
>
> So the history part is fairly easy. There's only one major rule, and one
> minor clarification:
>
> - You must never EVER destroy other peoples history. You must not rebase
>commits other people did. Basically, if it doesn't have your sign-off
>on it, it's off limits: you can't rebase it, because it's not yours.
>
>Notice that this really is about other peoples _history_, not about
>other peoples _code_. If they sent stuff to you as an emailed patch,
>and you applied it with "git am -s", then it's their code, but it's
>_your_ history.
>
>So you can go wild on the "git rebase" thing on it, even though you
>didn't write the code, as long as the commit itself is your private
>one.
>
> - Minor clarification to the rule: once you've published your history in
>some public site, other people may be using it, and so now it's clearly
>not your _private_ history any more.
>
>So the minor clarification really is that it's not just about "your
>commit", it's also about it being private to your tree, and you haven't
>pushed it out and announced it yet.
>
> That's fairly straightforward, no?
>
> Now the "clean" part is a bit more subtle, although the first rules are
> pretty obvious and easy:
>
> - Keep your own history readable
>
>Some people do this by just working things out in their head first, and
>not making mistakes. but that's very rare, and for the rest of us, we
>use "git rebase" etc while we work on our problems.
>
>So "git rebase" is not wrong. But it's right only if it's YOUR VERY OWN
>PRIVATE git tree.
>
> - Don't expose your crap.
>
>This means: if you're still in the "git rebase" phase, you don't push
>it out. If it's not ready, you send patches around, or use private git
>trees (just as a "patch series replacement") that you don't tell the
>public at large about.
>
> It may also be worth noting that excessive "git rebase" will not make
> things any cleaner: if you do too many rebases, it will just mean that all
> your old pre-rebase testing is now of dubious value. So by all means
> rebase your own work, but use _some_ judgement in it.
>
> NOTE! The combination of the above rules ("clean your own stuff" vs "don't
> clean other peoples stuff") have a secondary indirect effect. And this is
> where it starts getting subtle: since you most not rebase other peoples
> work, that means that you must never pull into a branch that isn't already
> in good shape. Because after you've done a merge, you can no longer rebase
> you commits.
>
> Notice? Doing a "git pull" ends up being a synchronization point. But it's
> all pretty easy, if you follow these two rules about pulling:
>
> - Don't merge upstream code at random points.
>
>You should _never_ pull my tree at random points (this was my biggest
>issue with early git users - many developers would just pull my current
>random tree-of-the-day into their development trees). It makes your
>tree just a random mess of random development. Don't do it!
>
>And, in fact, preferably you don't pull my tree at ALL, since nothing
>in my tree should be relevant to the development work _you_ do.
>Sometimes you have to (in order to solve some particularly nasty
>dependency issue), but it should be a very rare and special thing, and
>you should think very hard about it.
The only case I can think off here, is when I send a tree of bug fixes to
your tree during -rc and I want to make sure the drm-next tree is tested
with those fixes applied to it. Is that an acceptable time to pull in your
tree? Normally I rebase the drm-next tree on top of the drm-fixes tree so
I know the testing is done with all known fixes in it, however it seems I
should merge your tree at that point instead into drm-next.
Thanks for all this, its quite clear now, I should clean this mail up and
put it into the kernel documentation.
Dave.
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Re: [git pull] drm-next
On Sun, 29 Mar 2009, Dave Airlie wrote:
>
> My plans from now on are just to send you non-linear trees, whenever I
> merge a patch into my next tree thats when it stays in there, I'll pull
> Eric's tree directly into my tree and then I'll send the results, I
> thought we cared about a clean merge history but as I said without some
> document in the kernel tree I've up until now had no real idea what you
> wanted.
I want clean history, but that really means (a) clean and (b) history.
People can (and probably should) rebase their _private_ trees (their own
work). That's a _cleanup_. But never other peoples code. That's a "destroy
history"
So the history part is fairly easy. There's only one major rule, and one
minor clarification:
- You must never EVER destroy other peoples history. You must not rebase
commits other people did. Basically, if it doesn't have your sign-off
on it, it's off limits: you can't rebase it, because it's not yours.
Notice that this really is about other peoples _history_, not about
other peoples _code_. If they sent stuff to you as an emailed patch,
and you applied it with "git am -s", then it's their code, but it's
_your_ history.
So you can go wild on the "git rebase" thing on it, even though you
didn't write the code, as long as the commit itself is your private
one.
- Minor clarification to the rule: once you've published your history in
some public site, other people may be using it, and so now it's clearly
not your _private_ history any more.
So the minor clarification really is that it's not just about "your
commit", it's also about it being private to your tree, and you haven't
pushed it out and announced it yet.
That's fairly straightforward, no?
Now the "clean" part is a bit more subtle, although the first rules are
pretty obvious and easy:
- Keep your own history readable
Some people do this by just working things out in their head first, and
not making mistakes. but that's very rare, and for the rest of us, we
use "git rebase" etc while we work on our problems.
So "git rebase" is not wrong. But it's right only if it's YOUR VERY OWN
PRIVATE git tree.
- Don't expose your crap.
This means: if you're still in the "git rebase" phase, you don't push
it out. If it's not ready, you send patches around, or use private git
trees (just as a "patch series replacement") that you don't tell the
public at large about.
It may also be worth noting that excessive "git rebase" will not make
things any cleaner: if you do too many rebases, it will just mean that all
your old pre-rebase testing is now of dubious value. So by all means
rebase your own work, but use _some_ judgement in it.
NOTE! The combination of the above rules ("clean your own stuff" vs "don't
clean other peoples stuff") have a secondary indirect effect. And this is
where it starts getting subtle: since you most not rebase other peoples
work, that means that you must never pull into a branch that isn't already
in good shape. Because after you've done a merge, you can no longer rebase
you commits.
Notice? Doing a "git pull" ends up being a synchronization point. But it's
all pretty easy, if you follow these two rules about pulling:
- Don't merge upstream code at random points.
You should _never_ pull my tree at random points (this was my biggest
issue with early git users - many developers would just pull my current
random tree-of-the-day into their development trees). It makes your
tree just a random mess of random development. Don't do it!
And, in fact, preferably you don't pull my tree at ALL, since nothing
in my tree should be relevant to the development work _you_ do.
Sometimes you have to (in order to solve some particularly nasty
dependency issue), but it should be a very rare and special thing, and
you should think very hard about it.
But if you want to sync up with major releases, do a
git pull linus-repo v2.6.29
or similar to synchronize with that kind of _non_random_ point. That
all makes sense. A "Merge v2.6.29 into devel branch" makes complete
sense as a merge message, no? That's not a problem.
But if I see a lot of "Merge branch 'linus'" in your logs, I'm not
going to pull from you, because your tree has obviously had random crap
in it that shouldn't be there. You also lose a lot of testability,
since now all your tests are going to be about all my random code.
- Don't merge _downstream_ code at random points either.
Here the "random points" comment is a dual thing. You should not mege
random points as far as downstream is concerned (they should tell you
what to merge, and why), but also not random points as far as your tree
is concerned.
Simple version: "Don't merge unrelated downstream stuff into your own
topic branches."
Slightly more complex version: "Always have a _reason_ f
Re: [git pull] drm-next
> > This branch has a merge in it, due to conflicts with the Intel drm tree > > you already pulled. I've asked Eric to not send you direct pulls, he > > mentioned you said he should, but it really screws over my tree. I don't > > mind direct pulls outside the merge window as it usually smaller bug > > fixes, but during the merge window the chances of it getting messy like > > this tree has become just increase. > > Qutie frankly, I don't like how you always rebased patches, so I'd _much_ > rather see direct pulls than the alternative. And I can handle most merge > issues, and will ask submaintainers to merge for me only if it gets really > complicated. > > If this encourages people to keep DRI drivers more modular and > independent, that's all good. That's fine you only requested I stop rebasing Eric's tree since the last merge window, I haven't had to pull it since then to send to you. This merge there was 3 conflicts, I think they were mostly trivial, however there was also a warning fix in i915 for a return type not checked that no-one else picked up on. I'm still awaiting Documentation/linus-rules-for-git-trees.txt. I'm sure every other maintainer who is just guessing what the rules are would appreciate it as well. We don't all have the time of Ingo to do a branch per patch with a scary octopus merge every few weeks. My plans from now on are just to send you non-linear trees, whenever I merge a patch into my next tree thats when it stays in there, I'll pull Eric's tree directly into my tree and then I'll send the results, I thought we cared about a clean merge history but as I said without some document in the kernel tree I've up until now had no real idea what you wanted. Dave. -- -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
Re: [git pull] drm-next
On Sun, 29 Mar 2009, Dave Airlie wrote: > > This branch has a merge in it, due to conflicts with the Intel drm tree > you already pulled. I've asked Eric to not send you direct pulls, he > mentioned you said he should, but it really screws over my tree. I don't > mind direct pulls outside the merge window as it usually smaller bug > fixes, but during the merge window the chances of it getting messy like > this tree has become just increase. Qutie frankly, I don't like how you always rebased patches, so I'd _much_ rather see direct pulls than the alternative. And I can handle most merge issues, and will ask submaintainers to merge for me only if it gets really complicated. If this encourages people to keep DRI drivers more modular and independent, that's all good. Linus -- -- ___ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
