Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758667AbYAJWxS (ORCPT ); Thu, 10 Jan 2008 17:53:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754781AbYAJWxG (ORCPT ); Thu, 10 Jan 2008 17:53:06 -0500 Received: from turing-police.cc.vt.edu ([128.173.14.107]:54013 "EHLO turing-police.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754137AbYAJWxF (ORCPT ); Thu, 10 Jan 2008 17:53:05 -0500 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.2 To: Linus Torvalds Cc: "Pallipadi, Venkatesh" , ak@muc.de, ebiederm@xmission.com, rdreier@cisco.com, gregkh@suse.de, airlied@skynet.ie, davej@redhat.com, mingo@elte.hu, tglx@linutronix.de, akpm@linux-foundation.org, arjan@infradead.org, "Barnes, Jesse" , davem@davemloft.net, linux-kernel@vger.kernel.org, "Siddha, Suresh B" Subject: Re: [patch 02/11] PAT x86: Map only usable memory in x86_64 identity map and kernel text In-Reply-To: Your message of "Thu, 10 Jan 2008 14:15:25 PST." From: Valdis.Kletnieks@vt.edu References: <20080110184840.927409000@intel.com> <20080110184854.787474000@intel.com> <924EFEDD5F540B4284297C4DC59F3DEE5A2958@orsmsx423.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1200005441_2824P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Thu, 10 Jan 2008 17:50:41 -0500 Message-ID: <11912.1200005441@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1611 Lines: 42 --==_Exmh_1200005441_2824P Content-Type: text/plain; charset=us-ascii On Thu, 10 Jan 2008 14:15:25 PST, Linus Torvalds said: > Well, I think that /dev/mem should simply give them the right info. That's > what people use /dev/mem for - doing things like reading BIOS images etc. > > So returning *either* a zero page *or* stopping at the first hole is both > equally wrong. A case could be made that the /dev/mem driver should at *least* prohibit access to those memory ranges that the kernel already knows have (or might have) memory-mapped control registers with Bad Juju side-effects attached to them. Of course, a case could also be made that it should be permitted, because anybody who tries to read such memory addresses either (a) knows what they're doing or (b) is about to become an example of evolution in action... ;) (Personally, I keep a copy of Arjan's "restrict devmem" patch from Fedora around, so I guess that says which camp I belong in, and the fact it's a Fedora patch and not mainstream says something too...) --==_Exmh_1200005441_2824P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFHhqFBcC3lWbTT17ARAo7iAJ477vaLijWqQCycYpUEYKjEQVwOlwCePEw7 ePBn+L6JYmJjj014YYYF5Hw= =VlWe -----END PGP SIGNATURE----- --==_Exmh_1200005441_2824P-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/