git help needed for 2.6.34 kernel branch revival

Paul Fox pgf at laptop.org
Tue Aug 17 17:08:41 EDT 2010


daniel wrote:
 > Hi,
 > 
 > I'm playing with a few forward-looking ideas, one of them being
 > upgrading OLPC's kernel from version 2.6.31 to 2.6.34. And always open
 > to learning more about git...
 > 
 > Now, a good while back, Deepak started working on a 2.6.34 branch,
 > presumably forked from the 2.6.31 one that we were working on at the
 > time. I'm not sure of the details of how the branch or merge was done.
 > http://dev.laptop.org/git/olpc-2.6/log/?h=olpc-2.6.34-dev
 > 
 > It would be nice to be able to use his work, given that it appears a
 > big chunk of the work is already done. But there are 2 complications:
 > 
 >  1. The 2.6.31 branch has seen a lot of developments and fixes since
 > the 2.6.34 branch was created. So, we need to pull in all the recent
 > changes that we've made in olpc-2.6.31.
 >  2. The olpc-2.6.31 branch has merged in a few of the 2.6.31.x
 > "linux-stable" releases; those familiar with kernel development will
 > understand that those releases are outside of Linus' official tree
 > (i.e. the 2.6.31 to 2.6.32 history in Linus' tree does *not* literally
 > include the 2.6.31.x releases)
 > 
 > If I try the obvious:
 >  git checkout olpc-2.6.34-dev
 >  git merge olpc-2.6.31
 > 
 > then we end up pulling in all of the linux-stable-2.6.31 changes into
 > the 2.6.34 branch. For the majority there will be no problem. But now
 > and then, fixes are made in -stable which differ from the equivalent
 > fixes that end up in mainline. For example
 > http://dev.laptop.org/git/olpc-2.6/commit/?h=olpc-2.6.31&id=5c7fba322917ef918426
 > 76de55fba470bc2af5f3
 > (note how it says "fixed in a different way")

would it work better to merge each of the the -stable kernels
in turn?  because then you'd probably get the undo of the -stable
change along with the mainline change that supercedes it.  but that
might not work, and it would be a lot of merges.

paul

 > 
 > So I end up with a large task on my hands (finding all these little
 > differences and figuring out the right course of action), and a
 > resultant kernel that I don't really trust.
 > 
 > Another option could be to undo the merges of the linux-stable trees
 > from olpc-2.6.31. But I don't know how.
 > 
 > What's the best course of action?
 > 
 > 
 > Perhaps the best answer is "start again with a 2.6.34 rebase". I can
 > use this command to determine all the OLPC commits that aren't in
 > mainline or the linux-stable merges:
 > git log --pretty=oneline 120f68c4..olpc-2.6.31
 > (120f68c4 is the 2.6.31.6 linux-stable release commit, the last
 > 2.6.31-stable release merged into olpc-2.6.31)
 > 
 > Maybe this is the best course of action? The headache is that we're
 > looking at 399 commits.
 > 
 > 
 > On a separate note, I guess it would make sense for OLPC to define a
 > policy where -stable updates are not brought into the OLPC kernel
 > tree. This would avoid this headache in future, as the history would
 > flow consistent with Linus' tree.
 > 
 > 
 > Thoughts?
 > 
 > Thanks,
 > Daniel
 > _______________________________________________
 > Devel mailing list
 > Devel at lists.laptop.org
 > http://lists.laptop.org/listinfo/devel

=---------------------
 paul fox, pgf at laptop.org


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