From owner-freebsd-current@FreeBSD.ORG Wed Sep 22 17:57:47 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8045C16A4CF; Wed, 22 Sep 2004 17:57:47 +0000 (GMT) Received: from www.cryptography.com (li-22.members.linode.com [64.5.53.22]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1A2DB43D2D; Wed, 22 Sep 2004 17:57:47 +0000 (GMT) (envelope-from nate@root.org) Received: from [10.0.0.34] (adsl-67-127-84-57.dsl.snfc21.pacbell.net [67.127.84.57]) by www.cryptography.com (8.12.8/8.12.8) with ESMTP id i8MHvWDl003764; Wed, 22 Sep 2004 10:57:34 -0700 Message-ID: <4151BCF4.6070501@root.org> Date: Wed, 22 Sep 2004 10:57:08 -0700 From: Nate Lawson User-Agent: Mozilla Thunderbird 0.7.3 (Windows/20040803) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Bruce M Simpson References: <41421D6A.8070805@cronyx.ru> <41505663.40407@cronyx.ru> <4150607D.3020900@root.org> <200409211441.42325.jhb@FreeBSD.org> <20040922090406.GF4985@empiric.icir.org> In-Reply-To: <20040922090406.GF4985@empiric.icir.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: FreeBSD Current cc: Ian Freislich cc: John Baldwin cc: Roman Kurakin Subject: Re: mp_machdep.c (was Re: [Fwd: Re: Bug reports requested - acpi]) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Sep 2004 17:57:47 -0000 Bruce M Simpson wrote: > On Tue, Sep 21, 2004 at 02:41:42PM -0400, John Baldwin wrote: >>Umm, 0xa0000 is the start of Video RAM, so I sure hope the ACPI wake code >>doesn't try to write code into Video memory. The pmap_invalidate_page is >>certainly needed. > > This is more common than you'd think, by the way. The 0xA0000 range is > sometimes used as a place to hold 'hidden memory' used whilst servicing > an SMI; ie the pages are 'stolen' from main memory by the during BIOS > initialization using registers for APM/ACPI support in the chipset. > > Sometimes this is referred to as SMRAM or Systems Management Memory (SMM). > I posted some code just over a year ago illustrating how to access this > 'hidden segment' on the i440BX to the lists. Thanks, I work with SMIs a lot. :) The DDJ article is a good intro: http://www.rcollins.org/ddj/Jan97/Jan97.html -- Nate