*BSD News Article 8270


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Path: sserve!manuel.anu.edu.au!munnari.oz.au!uunet!mcsun!Germany.EU.net!unidui!du9ds3!veit
From: veit@du9ds3.fb9dv.uni-duisburg.de (Holger Veit)
Newsgroups: comp.unix.bsd
Subject: Re: dist.fs boot infinity-loop
Date: 19 Nov 92 18:50:51 GMT
Organization: Uni-Duisburg FB9 Datenverarbeitung
Lines: 44
Message-ID: <veit.722199051@du9ds3>
References: <BxxHtz.2sz@encore.com>
Reply-To: veit@du9ds3.uni-duisburg.de
NNTP-Posting-Host: du9ds3.fb9dv.uni-duisburg.de
Keywords: boot loop

In <BxxHtz.2sz@encore.com> idequesa@encore.com (Ivan Dequesada) writes:


>Does anyone know the difference between BSD's dist.fs and
>LINUX's dist.fs??

The main difference is, that 386bsd is running fully in protected mode
from the moment the boot sector of the disk or floppy has been read in.
That means, that there is no help from any BIOS or ROM to do any
initialization that is not done by the power-on-self-test or the ROM
bootstrap loader.
LINUX, instead follows the old tradition of Minix, and switches to
protected mode very late, when the whole kernel image has been loaded. This
allows for instance the switch to high resolution video modes (this is
available by the SVGA BIOS), which must be done by real register programming
in 386bsd. Once some code for this has been written for 386bsd, it can be used
universally, without any messing around with a VM86 syscall.

>It seems that some PCs (Including (but not limited to) Compaq
>Systems and TI's) hang in an infinite loop when booting from
>the dist.fs diskette (3 1/2", 1.44 Mbytes).
>This seems to be a compatability problem. However, it would be
>better to fix it in the diskette than in the BIOS-ROMs of
>tens of thousands of PCs. The fact that those PCs can boot the
>dist.fs with LINUX on it, indicates that the problem can be fix
>in the dist.fs.

The above is the main reason for the "fewer" problems with Linux boot, 
once you are in protected mode, Linux is no better than 386bsd.

>Mr. Jolitz, if you read this, ask Linus if he uses near or far
>pointers when booting.

Although I am not Bill, I think that this makes no difference.

>	idequesa@encore.com

Holger

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