Re: Kernel headers git tree

[David Woodhouse <dwmw2@infradead.org>]

On Fri, 2006-07-14 at 13:51 -0400, Daniel Barkalow wrote:
> I think that a program to generate a slave git tree based in some 
> user-modifiable way on a parent repository would be useful and 
> implementable. I'd thought a bunch about it a while ago, for extracting 
> separable parts of projects (e.g., make a kbuild project that's pulled out 
> of the kernel tree, but is still a regular git project to anyone who 
> doesn't know this). My conclusion was that you need a cache of mappings, 
> because otherwise you can't identify that you already have a transformed 
> version of a commit, because you don't know its transformed parents, 
> unless you've gone all the way back to the root (which doesn't have 
> parents).

Absolutely. You don't want to go all the way back to the root every time
-- it's an incremental process, and you have to cache the mappings from
objects in the 'master' tree to objects in the 'slave' tree.

My existing scripts already do that part -- I didn't think it was worth
commenting on.

http://david.woodhou.se/extract-jffs2-git.sh
http://david.woodhou.se/extract-khdrs-git.sh
http://david.woodhou.se/extract-khdrs-stage2.sh

And no, I don't do any further simplification of the graph of commits
other than what 'git-rev-list' does for me. I need to fully go over
Linus' last mail and understand it, but I think the conclusion is that
the above scripts are fine, and I can happily drop --topo-order from
them.

-- 
dwmw2