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From: Ray Lee <ray-lk@madrabbit.org>
Date: Thu, 11 Jun 2009 10:22:23 -0700
Message-ID: <2c0942db0906111022s442be8fbl47656a60e2619b9d@mail.gmail.com>
Subject: Re: [GIT PULL] Performance Counters for Linux
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, "David S. Miller" <davem@davemloft.net>,
       Stephane Eranian <eranian@googlemail.com>, linux-kernel@vger.kernel.org,
       Paul Mackerras <paulus@samba.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Thomas Gleixner <tglx@linutronix.de>
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On Thu, Jun 11, 2009 at 10:12 AM, Al Viro<viro@zeniv.linux.org.uk> wrote:
> On Thu, Jun 11, 2009 at 10:05:02AM -0700, Ray Lee wrote:
>> Packagers are quite used to taking a single source tree and building
>> multiple packages out of it. This isn't rocket science. It's the
>> multiple separate trees that need to be released in lock-step that are
>> headaches.
>
> Wrong.  Remember the fun bisecting around sysfs/udev incompatible change?
> Oops, went back past the cutoff line, got to downgrade udev for the next
> boot.  Oh, it oopses?  Too fucking bad, can't just boot the previous kernel,
> should've kept _two_ working ones so that with any userland state we could
> come back to working system.
>
> This isn't a rocket science, this is a goddamn load of horse manure.
> Packages that need to be updated in the lock-step *are* headaches from
> hell when you are trying to do development.  Even if you have all of
> them already built.

Well, welcome to our new world order of Xorg and udev and hal. I have
had to deal with bisecting the problem just as you have, and dealt
with the fallout.

The choices are:

 - Don't bisect, throw up your hands and hope someone else deals with it

 - keep the old versions around for installs, as you point out (I do
this regularly)

 - build all the packages every time

The last one is the most reasonable and I'd argue it's the right thing
to do. But it's tricky with multiple source trees -- which version of
udev works with this kernel again? A single source tree for packages
that are kept in lock-step, as so many seem to be, makes that a hell
of a lot easier on me.

But perhaps I'm an odd-ball.

I think your complaint is "Why the hell can't they have a stable ABI?"
Probably for the same reason anything so close to the hardware hasn't
had a stable ABI. I'm sure udev/hal/Xorg will have a stable
kernel-userland interface any day now. Once they do, I'm sure
everything else that touches the hardware so intimately will have a
stable ABI too.

Sheesh.
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