Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768Ab0LOQD7 (ORCPT ); Wed, 15 Dec 2010 11:03:59 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:34540 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751281Ab0LOQDz (ORCPT ); Wed, 15 Dec 2010 11:03:55 -0500 Date: Wed, 15 Dec 2010 16:03:23 +0000 From: Russell King - ARM Linux To: David Brown Cc: Catalin Marinas , Jeff Ohlstein , Daniel Walker , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Brian Swetland , Dima Zavin , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Bryan Huntsman , Steve Muckle Subject: Re: [PATCH v5 5/5] msm: add SMP support for msm Message-ID: <20101215160323.GA9937@n2100.arm.linux.org.uk> References: <1292302233-16194-1-git-send-email-johlstei@codeaurora.org> <1292302233-16194-6-git-send-email-johlstei@codeaurora.org> <20101215134414.GA8682@huya.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20101215134414.GA8682@huya.qualcomm.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1628 Lines: 34 On Wed, Dec 15, 2010 at 05:44:14AM -0800, David Brown wrote: > On Wed, Dec 15, 2010 at 12:35:18PM +0000, Catalin Marinas wrote: > > On 14 December 2010 04:50, Jeff Ohlstein wrote: > > > + ? ? ? outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1)); > > > + ? ? ? __asm__("sev"); > > > + ? ? ? dsb(); > > > > What's the need for the dsb() here (one before SEV maybe)? > > > > Also, do we need to add a "memory" clobber to the SEV asm, not sure > > whether the compiler would try to reorder the code. > > It doesn't seem to, but it seems to me that it would be allowed to, > so, I would think the "memory" clobber should be there. For each difference in the SMP and hotplug code from Realview (if it's mostly identical to Realview), I'd personally like to see explainations why it's necessary, either as comments in the code or at the very least in the commit log. As far as hotplug code goes, I wish folk would see what their hardware can actually do with the secondary CPUs - can they take the CPU fully offline and into a proper dormant state, and when they reawaken it, can they wake it in the same manner as the CPU is brought online during boot. Realview doesn't do this because it can't reset the secondary CPUs independent of the boot CPU, so the pattern it gives you should not be followed unless your hardware is similarly restricted. -- 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/