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From: David Miller <davem@davemloft.net>
Subject: Re: Linux 2.6.35/TIPC 2.0 ABI breaking changes
Date: Mon, 18 Oct 2010 15:17:08 -0700 (PDT)
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From: Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Mon, 18 Oct 2010 16:42:33 -0400

> If you have access to the user space code in question, you can just
> switch behaviour semantics based on the results of a uname call, knowing
> that this change was included in versions since approx last Feb.  There
> is also /proc/version which can be parsed manually if you prefer.

Requiring userspace to check kernel versioning information in order
to user an exported userspace API correctly is _ALWAYS_ _WRONG_.

You cannot and must not make backwards incompatible changes to
userspace interfaces.

Really, you can't.