From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [F.A.Q.] perf ABI backwards and forwards
	compatibility
Date: Tue, 08 Nov 2011 11:32:46 +0100
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Cc: Alexander Graf <agraf@suse.de>, Ted Ts'o <tytso@mit.edu>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	"kvm@vger.kernel.org list" <kvm@vger.kernel.org>,
	qemu-devel Developers <qemu-devel@nongnu.org>,
	Vince Weaver <vince@deater.net>,
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	Pekka Enberg <penberg@kernel.org>,
	Blue Swirl <blauwirbel@gmail.com>, "Frank
	Ch. Eigler" <fche@redhat.com>, Pekka Enberg <penberg@cs.helsinki.fi>,
	Avi Kivity <avi@redhat.com>,
	=?ISO-8859-1?Q?Am=E9rico?= Wang <xiyou.wangcong@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
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On Tue, 2011-11-08 at 11:22 +0100, Ingo Molnar wrote:
>=20
> We do even more than that, the perf ABI is fully backwards *and*=20
> forwards compatible: you can run older perf on newer ABIs and newer=20
> perf on older ABIs.=20

The ABI yes, the tool no, the tool very much relies on some newer ABI
parts. Supporting fallbacks isn't always possible/wanted.