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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.cs.su.oz.au!news.adelaide.edu.au!gateway.dircsa.org.au!cleese.apana.org.au!apanix.apana.org.au!miff From: miff@apanix.apana.org.au (Michael Smith) Newsgroups: comp.os.386bsd.questions Subject: Re: [FreeBSD] Booting frm sd0 as default? Date: 27 Aug 94 01:38:35 GMT Organization: Apanix Public Access Unix, +61 8 373 5485 (5 lines) Lines: 35 Message-ID: <miff.777951515@apanix.apana.org.au> References: <miff.777745860@apanix.apana.org.au> <Cv369J.KK3@cogsci.ed.ac.uk> NNTP-Posting-Host: seldon.apanix.apana.org.au Keywords: booting FreeBSD Firstly - my apologies for dredging up this topic. The problems I had were due to trying to do something serious while I was compiling 1.1.5 for the first time - something must have moved under me at some point in time and nothing after that worked. A fresh copy of the sources was all it took. richard@cogsci.ed.ac.uk (Richard Tobin) writes: >In article <miff.777745860@apanix.apana.org.au> miff@apanix.apana.org.au (Michael Smith) writes: >>I can type hd(1,a)/386bsd and boot from the second disk just dandy, >Which reminds me: why do you have to use hd(1,a) instead of sd(0,a)? Because the boot code reads the kernel using the bios, where the disks are numbered in order of appearance : in my case, the wd is 0x80 and the sd is 0x81, but the kernel wants a major/minor pair, where the wd is 0,0 and the sd is 4,0. If you have two wd's, they're 0,0/0,1 or 0x80/0x81, which is easy. If you have two sd's, they're 4,0/4,1 or 0x80/0x81 which is too. But if you have one of each, the boot code doesn't go looking at every disk first, so it can't tell this. The "hd" is a special case that assumes this : hd(0... goes to 0x81 and uses 0,0 while hd(1... goes to 0x81 and uses 4,0. Makes sense, no? 8) >Richard Tobin, HCRC, Edinburgh University R.Tobin@ed.ac.uk -- # mike smith : miff@apanix.apana.org.au - Silicon grease monkey # # "The question 'why are the fundamental laws of nature mathematical' # # then invites the trivial response 'because we define as fundamental # # those laws which are mathematical'". Paul Davies, _The_Mind_of_God_. #