From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <junkio@cox.net>
Subject: Re: Kernel headers git tree
Date: Thu, 13 Jul 2006 19:37:11 -0700
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To: David Woodhouse <dwmw2@infradead.org>
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	Woodhouse's message of "Fri, 14 Jul 2006 01:56:01 +0100")
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David Woodhouse <dwmw2@infradead.org> writes:

> On Thu, 2006-07-13 at 17:39 -0700, Junio C Hamano wrote:
>> With modern enough git, you can rewrite
>>         KBUILDSHA=`git ls-tree $TREE -- Kbuild | cut -f3 -d\  | cut -f1`
>> with
>>         KBUILDSHA1=`git rev-parse $TREE:Kbuild`
>
>
> Aha. Thanks.
>
>> I am not sure what function incparent() is trying to do with
>> this:
>> 
>>         git rev-list --max-count=1 --topo-order $1 -- . 
>
> Find the latest ancestor commit which actually changed any files. The
> first script has a similar line, except that it finds the latest
> ancestor which changed anything in include/
>
> Consider a kernel tree with commits A-->B-->C-->D, of which only A and C
> change anything in include/ and in fact only C actually changes the
> _exported_ headers after the unifdef and sed bits. 
>
> The first script (extract-khdrs-git.sh) creates a 'stage1' branch which
> only contains commits A'-->C', with the _exported_ header tree for each.
>
> The second script (extract-khdrs-stage2.sh) then creates the master
> branch with the same tree objects, but omitting the commits which don't
> change anything. So it contains only commit C''

I guess what I was getting at was if you can avoid creating
commits that do not change anything from previous in stage1
branch, you do not have to do this, but I haven't studied stage1
script deeply enough.