From owner-freebsd-arch@FreeBSD.ORG Wed Mar 23 22:46:32 2011 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E82871065675; Wed, 23 Mar 2011 22:46:32 +0000 (UTC) (envelope-from avg@freebsd.org) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id 934FF8FC0A; Wed, 23 Mar 2011 22:46:31 +0000 (UTC) Received: from porto.topspin.kiev.ua (porto-e.starpoint.kiev.ua [212.40.38.100]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id AAA16293; Thu, 24 Mar 2011 00:46:27 +0200 (EET) (envelope-from avg@freebsd.org) Received: from localhost.topspin.kiev.ua ([127.0.0.1]) by porto.topspin.kiev.ua with esmtp (Exim 4.34 (FreeBSD)) id 1Q2Wot-000F7N-6n; Thu, 24 Mar 2011 00:46:27 +0200 Message-ID: <4D8A7841.5080004@freebsd.org> Date: Thu, 24 Mar 2011 00:46:25 +0200 From: Andriy Gapon User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.15) Gecko/20110308 Lightning/1.0b2 Thunderbird/3.1.9 MIME-Version: 1.0 To: Peter Wemm References: <201103231029.p2NATtwg090498@lurza.secnetix.de> <20110323171443.GA59972@freebsd.org> <201103231426.27750.jhb@freebsd.org> In-Reply-To: X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Alexander Best , bz@freebsd.org, Oliver Fromme , freebsd-arch@freebsd.org Subject: Re: kernel memory checks on boot vs. boot time X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Mar 2011 22:46:33 -0000 on 23/03/2011 21:28 Peter Wemm said the following: > Part of the reason for this "check" is a sanity check to make sure we > enumerated memory correctly and that we have at least got basic ram > functionality. The existence of hw.physmem complicates this. On > machines where hw.physmem could be used to tell the kernel that there > was more ram present than the kernel enumerates (old bioses etc), this > was kind of important to sanity check. > > Even though modern hardware will fail windows compliance tests if the > SMAP etc is wrong, never underestimate the ability of bios makers to > find new and bizarre ways of screwing things up. > > I'd kinda like to keep a basic "is this real, non mirrored ram?" test > there. eg: the 2-pass step of writing physical address into each page > and then checking that they are still there on the second pass. > > Oh, did I mention the machine where the ACPI bios info tells the OS > that the current state is S3 (suspended to ram) instead of S0? > > When the kernel blows up at boot without a message.. we get the blame, > not the bios maker. I hear what you are saying, but is there any other OS that takes this level of responsibility? Should we either? I mean, hardware and BIOS vendors can screw up things in very creative ways and it's impossible to protect against that. When we are bug-compatible with some other OS, then it's one thing; but when we try to to be even "better" than that, that's quite another thing. -- Andriy Gapon