From owner-freebsd-hackers@FreeBSD.ORG Wed Oct 31 17:12:48 2007 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 37DC016A420 for ; Wed, 31 Oct 2007 17:12:48 +0000 (UTC) (envelope-from aduane@juniper.net) Received: from exprod7og106.obsmtp.com (exprod7og106.obsmtp.com [64.18.2.165]) by mx1.freebsd.org (Postfix) with ESMTP id DD5AE13C48E for ; Wed, 31 Oct 2007 17:12:47 +0000 (UTC) (envelope-from aduane@juniper.net) Received: from source ([66.129.224.36]) by exprod7ob106.postini.com ([64.18.6.12]) with SMTP; Wed, 31 Oct 2007 10:12:29 PDT Received: from pi-smtp.jnpr.net ([10.10.2.36]) by gamma.jnpr.net with Microsoft SMTPSVC(6.0.3790.1830); Wed, 31 Oct 2007 06:07:23 -0700 Received: from antipi.jnpr.net ([10.10.2.34]) by pi-smtp.jnpr.net with Microsoft SMTPSVC(5.0.2195.6713); Wed, 31 Oct 2007 09:07:04 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Date: Wed, 31 Oct 2007 09:00:38 -0400 Message-ID: <0FCFCF6165E968449991746EB91D614DB13F64@antipi.jnpr.net> In-Reply-To: <319cceca0710301402j48355b54gc572f9c76a39d5a8@mail.gmail.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: ``Stopping RAM access'' Thread-Index: Acgbc0OdkdXvOKs8QLOMiCSW8Wl/rAASlFog References: <0862634D7E37134986CB15DF2E4542BA1C1EE5@sbssrv.SALAG.local> <319cceca0710301402j48355b54gc572f9c76a39d5a8@mail.gmail.com> From: "Andrew Duane" To: X-OriginalArrivalTime: 31 Oct 2007 13:07:04.0959 (UTC) FILETIME=[EF1F20F0:01C81BBE] Subject: RE: ``Stopping RAM access'' X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Oct 2007 17:12:48 -0000 Well, if the system stops accessing RAM, you had better make sure that = *all* the instructions you need are already loaded into the L1 and L2 = caches. Otherwise you won't be able to turn RAM back on. That would = involve carefully preloading everything through use of the system's = appropriate PREFETCH calls, locking down the cache lines to make sure = nothing else disturbs them, turning off interrupts, and probably more. To actually turn off RAM, you'd have to power down or otherwise disable = the memory controller interface on your board. The procedures for that = would be highly platform dependent. /Andrew =20 > -----Original Message----- > From: owner-freebsd-hackers@freebsd.org [mailto:owner-freebsd- > hackers@freebsd.org] On Behalf Of Maslan > Sent: Tuesday, October 30, 2007 5:02 PM > To: Jaroszewski =A3ukasz > Cc: freebsd-hackers@freebsd.org > Subject: Re: ``Stopping RAM access'' >=20 > > Can anyone give me a clue, how one can ``stop'' system from = accessing > > RAM, and then allow it again?