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Date: Mon, 28 Nov 2005 15:07:50 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Zachary Amsden <zach@vmware.com>
CC: "Jeff V. Merkey" <jmerkey@wolfmountaingroup.com>,
       Bill Davidsen <davidsen@tmr.com>, Linus Torvalds <torvalds@osdl.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, Andi Kleen <ak@suse.de>,
       Gerd Knorr <kraxel@suse.de>, Dave Jones <davej@redhat.com>,
       Pavel Machek <pavel@ucw.cz>, Andrew Morton <akpm@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       Pratap Subrahmanyam <pratap@vmware.com>,
       Christopher Li <chrisl@vmware.com>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: [patch] SMP alternatives
References: <1132764133.7268.51.camel@localhost.localdomain> <20051123163906.GF20775@brahms.suse.de> <1132766489.7268.71.camel@localhost.localdomain> <Pine.LNX.4.64.0511230858180.13959@g5.osdl.org> <4384AECC.1030403@zytor.com> <Pine.LNX.4.64.0511231031350.13959@g5.osdl.org> <1132782245.13095.4.camel@localhost.localdomain> <Pine.LNX.4.64.0511231331040.13959@g5.osdl.org> <20051123214835.GA24044@nevyn.them.org> <Pine.LNX.4.64.0511231416490.13959@g5.osdl.org> <20051123222056.GA25078@nevyn.them.org> <Pine.LNX.4.64.0511231502250.13959@g5.osdl.org> <438B600C.1050604@tmr.com> <438B827A.2090609@wolfmountaingroup.com> <438B8BF8.4020604@vmware.com>
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Zachary Amsden wrote:
> 
> You need a way to type the lock semantics by memory region, and a 
> working hardware solution can not perform as well as a careful software 
> solution.  As was pointed out earlier, you can't use memory type 
> attributes to infer lock semantics, you must assume them in the decoder 
> or implement complex deadlock detection and recovery in silicon.
> 

Sure you can.  You just have to be prepared to take a microop exception 
if you speculate incorrectly.

	-hpa
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