From owner-freebsd-drivers@FreeBSD.ORG Thu Sep 6 09:28:12 2007 Return-Path: Delivered-To: freebsd-drivers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 55A4E16A417 for ; Thu, 6 Sep 2007 09:28:12 +0000 (UTC) (envelope-from die.gestalt@gmail.com) Received: from wx-out-0506.google.com (wx-out-0506.google.com [66.249.82.234]) by mx1.freebsd.org (Postfix) with ESMTP id 1409D13C45B for ; Thu, 6 Sep 2007 09:28:11 +0000 (UTC) (envelope-from die.gestalt@gmail.com) Received: by wx-out-0506.google.com with SMTP id i29so88162wxd for ; Thu, 06 Sep 2007 02:28:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; bh=S1buqlhhupkTJBYZlAs1QnpHB6EqdLWl4u5cqZrNFEM=; b=b8bvV/0oMI01+mxxlzNnJRCdR0PxRQtmTuHt4BAUqihOzdRDRXCSw0GTRSa5gGKGNSPodQKUc7YMjy5UnYp1oprEfrbdoZiBYiib/ZVEbcv3UyDN/1pg4w0uHghdHSK8pW1WLOu0lbGe13Yag96St3ySaddUg08+6pF5kItt9MY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=RfSfFPhtFeRWQndGKeNY61pttOz/Tji/XApQHEWU8xEwHjvh/goZ0SFBveYybWvMOI20TdzKgxE07uHAJwsyaHFkHeb67wjLsQ9iPaMORygJcYRJ5txWHCRLN5juwc+J6SB4zWKNW5eE8SpUETtdkJMS+XmdFj8XcmEnbXtYGQA= Received: by 10.90.54.4 with SMTP id c4mr783390aga.1189070883852; Thu, 06 Sep 2007 02:28:03 -0700 (PDT) Received: by 10.90.95.4 with HTTP; Thu, 6 Sep 2007 02:28:03 -0700 (PDT) Message-ID: <5bf3e10d0709060228s44f9a3efl886512e186c86448@mail.gmail.com> Date: Thu, 6 Sep 2007 11:28:03 +0200 From: "Die Gestalt" To: freebsd-drivers@freebsd.org In-Reply-To: <5bf3e10d0709050757vfb87ef4m499339ff0bb4724d@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <5bf3e10d0709050757vfb87ef4m499339ff0bb4724d@mail.gmail.com> Subject: Re: Physical address X-BeenThere: freebsd-drivers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Writing device drivers for FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Sep 2007 09:28:12 -0000 What I did is start a VMWare running FreeBSD, boot and freeze at logon, open the vmem file in a Hex editor and see that there is stuff between 0x1000 - 0x4000. The memory is clear (as expected) after 0x4000 till the kernel (after the first megabyte). I have no idea what it is and where it comes from, especially since I think pages are cleared when mapped, right? That would mean that it cannot be a residue from the boot sequence (unless I'm wrong). Any idea? -- Die Gestalt On 9/5/07, Die Gestalt wrote: > Hi all, > > I would like to know if there are drivers in a vanilla FreeBSD kernel > that write to *physical* memory addresses between 0x1000 and 0x4000. > > From what I inderstand the region between 0x1000 and the first > megabyte is mapped read only, but that doesn't prevent you from > accessing the region if you really want to. > > Hope my question makes sense. > > -- > > Die Gestalt >