Re: Kernel headers git tree

[David Woodhouse <dwmw2@infradead.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