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Re: [Qemu-devel] What does code_copy_enabled do?

From: Rob Landley
Subject: Re: [Qemu-devel] What does code_copy_enabled do?
Date: Mon, 11 Feb 2008 15:19:08 -0600
User-agent: KMail/1.9.6 (enterprise 0.20070907.709405)

On Monday 11 February 2008 14:38:42 Johannes Schindelin wrote:
> Hi,
> On Mon, 11 Feb 2008, Felipe Contreras wrote:
> > The advantage of using SVN is that most drcs play along with it quite
> > decently. Something that doesn't happen with CVS.
> So you're saying in order to use a DVCS you would need to switch to a

No, you need to switch _off_ of CVS.

CVS hasn't got the concept of "changesets".  You can treat a real CVCS as a 
DVCS that' s never branched, just a linear series of changesets with no merge 
nodes.  But CVS _isn't_ a real CVCS.  It's not a series of changesets, it's a 
bunch of separately tracked files.

You know how a single patch can touch a dozen different files?  CVS doesn't 
understand that.  Its dumber than the "patch" program.  In CVS, every single 
file stands alone, its history unrelated to any of the others.  Out of sheer 
self-preservation, most CVS users check in changes to lots of different files 
at once, with identical comments, so you can go back later and match changes 
up by timestamp and check that the comments match.  But this is just a 
heuristic, dependent on the behavior of the users, and it only sort of works 
at the best of times because unless your CVS server is infinitely fast, the 
timestamps won't be _identical_ but just _close_.  How close is close enough?  
Don't go there.  (I tried to write such a script once.  It hurt.)

But having to do data mining in order to detect changesets is an evil 
specialized black art, it breaks easily, and generally you want to convert up 
to at least something that understands changesets and NEVER LOOK BACK.

> Puzzled,
> Dscho

"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.

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