Date: Fri, 11 Oct 2002 08:47:13 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: ticso@cicely.de Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, freebsd-alpha@FreeBSD.ORG Subject: Re: booting UFS2 on alpha (was: cvs commit: src/sys/boot/common ufsread.c) Message-ID: <15782.51281.422120.59406@grasshopper.cs.duke.edu> In-Reply-To: <20021011104520.GY17920@cicely8.cicely.de> References: <20021010210124.GV17920@cicely8.cicely.de> <14845.1034332326@critter.freebsd.dk> <20021011104520.GY17920@cicely8.cicely.de>
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Bernd Walter writes: > > Is there some place which documents what the requirements for being > > a valid boot-block is ? > > None that I know about. > Maybe someone else on the alpha list knows? > Pages (III) 3-36 and 3-37 of the brown book describe the boot block format. Bascially, everything below offset 480 (which is where the count goes) is reserved. 488 is the starting lbn, 496 are the flags, and 504 is a checksum: 63............................,.0 |Reserved (VAX compat) | :BB |Reserved (Expansion) | :+136 |Reserved | :+472 |Count (LBNS) | :+480 |Starting LBM | :+488 |Flags | :+496 |Checksum | :+504 ................................ :+512 The first thing I'd look at is the checksum. The brown book has this to say about the checksum: "The console computes the checksum of the first 63 quadwords in the block as a 64-bit sum, ignoring overflow. The computation includes both reserved regions." Its too bad we don't have a Bird to try these on. They'ed spit out the AUDIT_CHECKSUM_GOOD, AUDIT_LOAD_BEGINS, AUDIT_LOAD_DONE messages to let you know where in the bootstrap it failed. Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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