Date: Thu, 9 Dec 1999 03:33:10 -0500 (EST) From: Robert Watson <robert@cyrus.watson.org> To: Neil Blakey-Milner <nbm@mithrandr.moria.org> Cc: freebsd-hackers@freebsd.org Subject: Re: question about boot loaders Message-ID: <Pine.BSF.3.96.991209032956.26554E-100000@fledge.watson.org> In-Reply-To: <19991209102159.B88680@ns1.sunesi.net>
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On Thu, 9 Dec 1999, Neil Blakey-Milner wrote: > On Thu 1999-12-09 (02:46), Robert Watson wrote: > > Once we get into boot2 land, I recognize the FreeBSD-specific loading > > code, etc. What I don't know much about is those first three 512-byte > > chunks of code. Boot0 appears to be booteasy, but given some ignorance > > about the i386 boot process, I'm not sure whether it's loaded by mbr, or > > by the bios, and where it lives partition-wise. Similarly, how boot1 fits > > into it the whole scheme--I assume this is FreeBSD-specific as it knows > > about boot2, but don't know where it lives, etc. Preferably, afterwards, > > also drop the results into sys/boot/i386/README. :-) > > I wrote up some basic stuff, which doesn't seem quite to describe > what you're after, but which may be of use, at > http://rucus.ru.ac.za/~nbm/boot/ > > It's intended for the handbook, but I haven't had time since starting > my new job to work on it much more. Looks interesting, but doesn't seem to mention the mbr/mbr.s code, and I'm not sure how this fit into the picture. There seem to be three 512-byte chunks of code: -r--r--r-- 1 root wheel 512 Sep 16 18:46 mbr -r--r--r-- 1 root wheel 512 Sep 16 18:46 boot0 -r--r--r-- 1 root wheel 512 Sep 16 18:46 boot1 -r--r--r-- 1 root wheel 7680 Sep 16 18:46 boot2 -r-xr-xr-x 1 root wheel 131072 Sep 16 18:46 loader* When there were two of them, I understood pretty much what was going on. Now there are three, and I clearly haven't been keeping a close enough eye on what is going on, because now I'm confused whereas previously I wasn't :-). Robert N M Watson robert@fledge.watson.org http://www.watson.org/~robert/ PGP key fingerprint: AF B5 5F FF A6 4A 79 37 ED 5F 55 E9 58 04 6A B1 TIS Labs at Network Associates, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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