From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rikard Lang Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Message-Id: <3CCA5A43-F904-4666-BCBC-C4870E4A9C2D@gmail.com> Date: Sun, 24 Feb 2013 11:48:47 +0100 To: 9fans@9fans.net Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\)) Subject: [9fans] Virtualbox and real mode Topicbox-Message-UUID: 1e6ed422-ead8-11e9-9d60-3106f5b1d025 My first post to 9fans; Hi! I am currently running 9Front on real hardware (mini-itx board with an = Atom CPU), I also run 9Front using Virtualbox. I have had issues getting = regular Plan 9 to install using Virtualbox. I know it wasn't a problem = in the past. Anyway, as I was walking through some sites related to this = I found this post: "I had a look at Plan 9 and I can only say that their idea of real mode = is miles away from Intel's. Plan 9 crashes because it calls BIOS with an = environment that only vaguely resembles real mode in that CR0.PE is 0, = but segment limits and attributes are totally all over the place. For = example they leave the 'B' bit for the stack segment set, which causes = rather interesting behavior of instructions that manipulate the stack. = That then triggers an extremely obscure bug in VirtualBox which probably = affects no other OS on the planet. The Plan 9 folks should probably re-read chapter 9.9.2 (Switching Back = to Real-Address Mode) of the Intel 64/IA-32 SDM (Volume 3) and implement = their mode switching code the way Intel says they should. This is their = code in sys/src/9/pcboot/realmode0.s." The post is located at: = https://forums.virtualbox.org/viewtopic.php?f=3D4&t=3D52431 It was one of very few posts that contained any technical information = whatsoever. Most posts I come across just say that the installation = hangs. I do not know if the above is of any help or even useful in any = way, but I thought I'd post it here, since it might help. --=20 Rikard Lang