Re: linux-next: manual merge of the xen tree with the tip tree

From: Jeremy Fitzhardinge
Date: Fri Oct 22 2010 - 14:39:35 EST


On 10/22/2010 01:01 AM, Ingo Molnar wrote:
> * Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
>
>> Hi all,
>>
>> Today's linux-next merge of the xen tree got a conflict in
>> arch/x86/mm/init_32.c between commit
>> 1d931264af0f10649b35afa8fbd2e169da51ac08 ("x86-32, memblock: Make
>> add_highpages honor early reserved ranges") from the tip tree and commit
>> 07147a06ac3b1b028124ea00ba44e69eb8ea7685 ("x86/32: honor reservations of
>> high memory") from the xen tree.
> Jeremy,
>
> Commit 07147a06ac is all over the x86 tree:
>
> arch/x86/mm/init_32.c | 42 ++++++++++++++++++++++++++++++++----------
> include/linux/early_res.h | 3 +++
> kernel/early_res.c | 30 ++++++++++++++++++++++++++++++
> 3 files changed, 65 insertions(+), 10 deletions(-)
>
> ... but there's no x86 person who acked it or was Cc:-ed to this commit AFAICS. It
> was not even posted to lkml! Nor does the commit title suggest that it affects core
> kernel code as well.
>
> Also, the AuthorDate field is a total lie:
>
> commit 07147a06ac3b1b028124ea00ba44e69eb8ea7685
> Author: Gianluca Guida <gianluca.guida@xxxxxxxxxx>
> AuthorDate: Sun Aug 2 01:25:48 2009 +0100
> Commit: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> CommitDate: Mon Oct 4 14:22:11 2010 -0700
>
> x86/32: honor reservations of high memory
>
> This commit was written on Aug 2 2009, really? kernel/early_res.c, which is modified
> by half of this commit, was _CREATED_ in February 2010 ...

Most of the code in early_res.c was simply moved from
arch/x86/.../e820.c, so the patch chunks were applied to the new file
when the code was moved.

> I realize that some original patch, much different from this one, was probably
> written in 2009, and that via a series of undocumented rebases and modifications to
> the patch you achieved this state.

The modified code was almost entirely unchanged over that period, so the
datestamp and original authorship of the patch was basically correct.

However...

> Crap like that is just _NOT_ acceptable, and you know that perfectly well - if you
> do this to arch/x86/ i'll be forced to ask for the Xen tree to be removed from
> linux-next and be done via the x86 tree again.

Hey, hey, hold your horses. This is a wildly obsolete patch that we
were discussing a few weeks ago, but Yinghai did a proper alternative
for the memblock universe.

It was never in linux-next, and never intended to be. I'm not sure why
it has appeared in linux-next now; it isn't in my branch. I wonder if
it appeared in another Xen-related branch. Let me investigate.

J
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