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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Some questions about 386BSD
Message-ID: <1992Oct18.082931.22482@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: University of Utah Computer Center
References: <Oct16.224608.51840@yuma.ACNS.ColoState.EDU>
Date: Sun, 18 Oct 92 08:29:31 GMT
Lines: 58
In article <Oct16.224608.51840@yuma.ACNS.ColoState.EDU>, barnesdo@CS.ColoState.EDU (douglas barnes) writes:
|> I have been following the discussions on this newsgroup very closely
|> but I remain somewhat confused on a couple of topics because conflicting
|> posts were made and no clear victor emerged (or I missed the article
|> where one was declared).
|>
|> Here goes:
|>
|> 1) Various posts have been made to the effect that using more than
|> 16MB to run 386BSD is a *bad thing*. I also remember similar
|> problems with earlier versions of Interactive. In both cases the
|> difficulty was attributed to the limited address space for devices
|> (say SCSI controllers) to DMA into. Is this a real problem for
|> 386BSD? Is anyone successfully running with >16MB of memory?
386BSD, at least under Julian's stuff, if not generally, will use "bounce
buffers" -- buffers accessable in the 24bit address range of the current
DMA limits on ISA ans some EISA hardware. I have been running for a long
time with 24Meg and 32 Meg on several machines, and seen no real problems
attributable to >16Meg of RAM.
|> 2) Several approaches have been outlined for causing DOS and 386BSD
|> to coexist. Some apparently do not work for IDE drives. Could
|> someone mail me or repost the canonical method for installing
|> multiple OSs on a *SCSI* drive? Also, I appreciate the ongoing
|> efforts to discern exactly what the deal is with IDE, as the
|> next available platform available to me has IDE drives.
The stuff in the installation notes should work fine for this.
|> 3) That handy little program "os-bs" does not permit booting from
|> other hard drives. Is there a fundamental reason for this, or
|> could such a utility theoretically boot from another drive? Is
|> there a utility that does this?
The fundamental reason for this is the fact that DOS BIOS likes to recognize
a single drive as the "primary" drive. I don't know if Julian's stuff gets
around this for operating systems other than 386BSD (like "can I type 'DOS'
at the prompt to boot off my DOS partition?"). I suspect it does not. This
is basically the next step. Booting off other drives requires code that takes
more room than is available in the DOS MBR space. This code generally comes
from it's own partition, or by modifying the way the MBR code is laid out.
Look in the previous articles by Julian Elischer for one excellent one dealing
with the whole of how booting works.
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
--
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Get the 386bsd FAQ from agate.berkeley.edu:/pub/386BSD/386bsd-0.1/unofficial
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