From mboxrd@z Thu Jan  1 00:00:00 1970
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Compat 32-bit syscall entry from 64-bit task!?
Date: Fri, 20 Jan 2012 14:41:51 -0800
Message-ID: <4F19EDAF.2000109@zytor.com>
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Cc: Denys Vlasenko <vda.linux@googlemail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Indan Zupancic <indan@nul.nu>,
	Andi Kleen <andi@firstfloor.org>,
	Jamie Lokier <jamie@shareable.org>,
	Andrew Lutomirski <luto@mit.edu>,
	Oleg Nesterov <oleg@redhat.com>,
	Will Drewry <wad@chromium.org>, linux-kernel@vger.kernel.org,
	keescook@chromium.org, john.johansen@canonical.com,
	serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com,
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	segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org,
	scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi,
	viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org,
	khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com,
	ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de,
	dhowells@redhat.com, daniel.lezcano@free.fr,
	linux-fsdevel@vger.kernel.org,
	linux-se
To: Roland McGrath <mcgrathr@google.com>
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On 01/20/2012 02:40 PM, Roland McGrath wrote:
> If you change the size of a regset, then the new full size will be the size
> of the core file notes.  Existing userland tools will not be expecting
> this, they expect a known exact size.  If you need to add new stuff, it
> really is easier all around to add a new regset flavor.  When adding a new
> one, you can make it variable-sized from the start so as to be extensible
> in the future.  We did this for NT_X86_XSTATE, for example.
>

Yes, that definitely seems cleaner.

	-hpa