From owner-freebsd-hackers Thu Dec 6 9:25:12 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from mail11.speakeasy.net (mail11.speakeasy.net [216.254.0.211]) by hub.freebsd.org (Postfix) with ESMTP id C4EF937B41B for ; Thu, 6 Dec 2001 09:25:04 -0800 (PST) Received: (qmail 21088 invoked from network); 6 Dec 2001 17:25:03 -0000 Received: from unknown (HELO laptop.baldwin.cx) ([64.81.54.73]) (envelope-sender ) by mail11.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 6 Dec 2001 17:25:03 -0000 Message-ID: X-Mailer: XFMail 1.4.0 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <15375.42185.608553.610033@caddis.yogotech.com> Date: Thu, 06 Dec 2001 09:24:58 -0800 (PST) From: John Baldwin To: Nate Williams Subject: Re: Re[2]: switching to real mode Cc: freebsd-hackers@FreeBSD.ORG, Ronald G Minnich Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 06-Dec-01 Nate Williams wrote: >> > I saw an example of switching in real mode in linux' sources (it looks >> > pretty clear) and thouhgt it is possible to do the same under FreeBSD. >> > The problem is I'm absolutely lost in FreeBSD's physical memory management >> > implementation (page tables and directory and so on). >> >> That code is quite broken. You need to check out the ones I mentioned >> earlier. All that the code does in the linux kernel is fail badly. >> >> Actually there used to be in freebsd some really nice code for popping >> into real mode and back again. It was to support calling BIOS for certain >> things. > > I believe the code is still there, and it's used for APM bios calls, > if I remember correctly. It uses VM86 mode, not real mode. Going back and forth to real mode is too expensive. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message