From owner-freebsd-hackers Thu Dec 6 8:51:42 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from scaup.prod.itd.earthlink.net (scaup.mail.pas.earthlink.net [207.217.120.49]) by hub.freebsd.org (Postfix) with ESMTP id 7ED2837B416 for ; Thu, 6 Dec 2001 08:51:36 -0800 (PST) Received: from dialup-209.245.132.144.dial1.sanjose1.level3.net ([209.245.132.144] helo=mindspring.com) by scaup.prod.itd.earthlink.net with esmtp (Exim 3.33 #1) id 16C1kF-0003D3-00; Thu, 06 Dec 2001 08:51:35 -0800 Message-ID: <3C0FA21D.86860C48@mindspring.com> Date: Thu, 06 Dec 2001 08:51:41 -0800 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Ronald G Minnich Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: switching to real mode References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit 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 Ronald G Minnich 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. It's still there. See the code in /sys/boot, in particular, the bios code in boot2 and boot 3. It isn't enough to do what he wants, though. He wants to effectively return to real mode and jump to a real mode boot strap loader, as if in the second stage of a boot manager, after the partition to boot has been selected (e.g. "Reboot to Linux", "Reboot to Windows", "Reboot to XXX"). I understand the desire now. It all depends on how much work he's willing to do. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message