Re: Git help for kernel archeology, suppress diffs caused by CVS keyword expansion

From: Jan Engelhardt <jengelh@computergmbh.de>
Date: Jul 22, 2007, 19:47 UTC
Message-ID: <Pine.LNX.4.64.0707222139400.15705@fbirervta.pbzchgretzou.qr>
In-Reply-To: <9e4733910707221148g69d7600bk632abb7452ce9c7c@mail.gmail.com>

On Jul 22 2007 14:48, Jon Smirl wrote:

Show 11 quoted lines

>
> It would really be useful if git diff had an option for suppressing
> diffs caused by CVS keyword expansion. I run into this problem over
> and over when trying to recover stuff out of old kernel sources that
> people checked into CVS and then posted CVS diffs to fulfill their GPL
> obligations. I sometimes wonder if vendors are doing this on purpose
> to make it more difficult to recover the changes they made to the
> code.
>
> To prevent this in the future, I'd love to see a patch removing all
> CVS keywords from the kernel sources.

I say: yes please. Even svn (which Linus dislikes very much) has cvs keywords disabled by default. And at the same time, a patch to CodingStyle not to include CVS tags, and a patch to checkpatch.pl to enforce it :)

> Quick grep of kernel shows 1,535 $Id, 197 $Log, 441 $Revision, 144 $Date. I
> guestimate that this would remove about 5,000 lines form the kernel source
> and touch 1,700 files. Would this be accept or do those expansions contain
> useful info?

Common argument for $Id$ tags has been, that upon a problem, a user can look into dmesg (or whatever log is appropraite - it's not limited to the kernel) for the version string instead of figuring it out himself (by means or rpm -q, or whatever hides it).

For the Linux kernel however, I do not think it is important, since:

- the code of a module changes faster than you can think (e.g.
  a change in the network code touched a network filesystem). Result:
  same $Id$ tag in the vendor's version AND the mainline version.
  So the tag is useless.

- you know what version you are running, mingetty usually prints it
  for you; uname -a also shows it.

- if you have a problem, people kindly ask you to bisect anyway, in
  which case $Id$ numbers become irrelevant anyway, because you got
  the git SHA1 ids.

Yep, that's pretty much it from my side. Conclusion: Remove CVS tags from kernel.

Jan