Re: Kernel headers git tree

From: David Woodhouse <dwmw2@infradead.org>
Date: Jul 14, 2006, 09:38 UTC
Message-ID: <1152869915.3191.12.camel@pmac.infradead.org>
In-Reply-To: <Pine.LNX.4.64.0607132251310.5623@g5.osdl.org>

On Thu, 2006-07-13 at 22:52 -0700, Linus Torvalds wrote:

> Btw, I'm actually surprised that my path simplification didn't filter out 
> the "." and make it mean exactly the same as not giving a path at all. I 
> thought I had done that earlier, but if you say "-- ." matters, then it 
> obviously does..

In this specific case where I have a whole bunch of commits which don't actually change anything, it definitely does make a difference...

hera /home/dwmw2 $ export GIT_DIR=/pub/scm/linux/kernel/git/dwmw2/kernel-headers.git hera /home/dwmw2 $ git-rev-list --max-count=5 stage1 e4e2fcc2c333aac5f6331c1df256ff28d7ee76d7 32ca8021c5ab7b9d44e8a08aeb53e52af5223fec 6b8380885464e069ae22e1e04f4a905c9e918f4e 2dee58696cab32506f655cb94a63cf4b18a13b37 402429bc9ac5eb891f253f6dae1228338f7f0ea5 hera /home/dwmw2 $ git-rev-list --max-count=5 stage1 -- . d1aba9314210d616cd2aa9ee91176c1dba6d3834 0b627fd403d6319fe50fbd8b95d5ea02017731fa b29cfa21bbdfc25271ef446b9df94ed8b5425711 e2407b6a9a643b378700474c9079dd8620e820ed c0df084d3e2ec0df6dafda8099e7c27c29760843

Junio is right -- if I can avoid creating commits that don't change any files in the stage1 branch, then I don't have to do this. That would be _hard_ though...

Currently, the selection of commits from your original tree to be represented in the stage1 branch is simple -- it's "those commits which touch include/". And 'rev-list -- include' works nicely for that.

Yet what I actually want in the final result is "those commits which change the result of the _exported_ headers". It's slightly less realistic to want rev-list to find that for me directly from the original kernel tree without having done the export step in stage1 -- what I need to do is create the exported header tree for each commit which _might_ change it, then filter out the commits which don't _actually_ change it.

The extra commits in the stage1 branch are cheap enough -- by definition they don't lead to any extra tree or blob objects. I think the two-stage export is probably the best approach, unless I'm missing something.

-- 
dwmw2