From owner-freebsd-hackers@FreeBSD.ORG Thu Jan 15 19:39:38 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DB7E916A4CE for ; Thu, 15 Jan 2004 19:39:38 -0800 (PST) Received: from smtp3.Stanford.EDU (smtp3.Stanford.EDU [171.67.16.117]) by mx1.FreeBSD.org (Postfix) with ESMTP id 16A5143D64 for ; Thu, 15 Jan 2004 19:39:38 -0800 (PST) (envelope-from tedu@stanford.edu) Received: from elaine30.Stanford.EDU (elaine30.Stanford.EDU [171.64.15.105]) by smtp3.Stanford.EDU (8.12.10/8.12.10) with ESMTP id i0G3daw6006843; Thu, 15 Jan 2004 19:39:37 -0800 Date: Thu, 15 Jan 2004 19:39:36 -0800 (PST) From: Ted Unangst To: Steve Watt In-Reply-To: <200401142055.i0EKtnL6085950@wattres.Watt.COM> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: hackers@freebsd.org Subject: Re: kernel environment between reboots, diskless X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Jan 2004 03:39:39 -0000 On Wed, 14 Jan 2004, Steve Watt wrote: > I'm trying to see if there's a way to get that information into the > loader (or the driver) in some way that doesn't require rewriting a file > in the flash every reboot, to avoid flash write cycles. > > I know there's some amount of NVRAM in PCs, but didn't spot anything > about how to get at it from the driver. It'd be nice, for this > sort of application, if there was a way to stash somewhere between > 2 and 8 bytes somewhere... many (most?) PCs don't clear RAM on soft reboot, so stuff like the message buffer survives. try mapping the same physical address, out of the way of other code, and leaving your data there. --