In-Reply-To: <20060227190150.GA9121@kroah.com>
References: <20060227190150.GA9121@kroah.com>
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Cc: linux-kernel@vger.kernel.org, torvalds@osdl.org,
       Andrew Morton <akpm@osdl.org>, davej@redhat.com, perex@suse.cz,
       gregkh@suse.de, Kay Sievers <kay.sievers@vrfy.org>
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From: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: [RFC] Add kernel<->userspace ABI stability documentation
Date: Mon, 27 Feb 2006 13:22:05 -0600
To: Greg KH <greg@kroah.com>
Sender: linux-kernel-owner@vger.kernel.org
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On Feb 27, 2006, at 1:01 PM, Greg KH wrote:

> Hi all,
>
> As has been noticed recently by a lot of different people, it seems  
> like
> we are breaking the userspace<->kernelspace interface a lot.  Well, in
> looking back over time, we always have been doing this, but no one  
> seems
> to notice (proc files changing format and location, netlink library
> bindings, etc.)
>
> Linux is a dynamic system, we add and change things all the time based
> on the need of its developers and users.  Because of this, we now  
> run on
> more platforms than any other operating system ever has, from the
> world's top supercomputers, to the phone in your pocket.  It is how we
> have survived so far, and is how we will survive in the future.
>
> In order to ensure that we can continue to be dynamic in the  
> future, and
> not get bogged down by interfaces that are half-baked, or just turn  
> out
> to be wrong once we implement them and find ways to break them (anyone
> remember the sys_futex evolution?) we need to be able to handle the
> changes in the userspace<->kernelspace ABI properly.
>
> So, here's a first cut at how we can do this.  Lots of other operating
> systems explicity document what the interfaces to it are, and give a
> "stability" rating of those interfaces (for one example, look at
> http://opensolaris.org/os/community/onnv/devref_toc/devref_7/ ).  I  
> feel
> that we too need to document this interface, in order to keep everyone
> in the loop and not cause any unwanted surprises at times they do not
> need them (like right before a company's deadline.)
>
> I've sketched out a directory structure that starts in
> Documentation/ABI/ and has five different states, "stable", "testing",
> "unstable", "obsolete", and "private".  The README file describes  
> these
> different states, and how things can move between them.  I've also
> seeded the directories with some well known examples of the different
> interfaces that are already in these states.
>
> So, any comments?  Criticisms?

It would be nice if we can come up with some way for Linus to  
document state changes in his release notes.

- kumar
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