From owner-freebsd-hackers Fri Jan 5 00:09:54 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id AAA17617 for hackers-outgoing; Fri, 5 Jan 1996 00:09:54 -0800 (PST) Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id AAA17529 for ; Fri, 5 Jan 1996 00:09:18 -0800 (PST) Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id SAA16788; Fri, 5 Jan 1996 18:56:16 +1100 Date: Fri, 5 Jan 1996 18:56:16 +1100 From: Bruce Evans Message-Id: <199601050756.SAA16788@godzilla.zeta.org.au> To: bde@zeta.org.au, terry@lambert.org Subject: Re: X for install Cc: freebsd-hackers@freebsd.org, jkh@time.cdrom.com, obrien@cs.ucdavis.edu, phk@critter.tfs.com Sender: owner-hackers@freebsd.org Precedence: bulk >> >Make sure the 32 bit absolute sector address in the partition table >> >entry is correct. It won't be for DOS fdisk versions before 3.0x, >> >and some utilities don't set it correctly. >> >> Such drives aren't supported. Checking the absolute sector address >> requires knowing the BIOS geometry. Drivers already check it, based >> on the guessed BIOS geometry, but since the BIOS geometry isn't known >> for sure, inconsistencies aren't fatal, and since some users don't >> like to see warnings at boot time, warnings about the inconsistencies >> are disabled. >So ask the BIOS by making a BIOS call from protected mode. It's the >INT 13, AH=0x08, AL= call. The BIOS doesn't work in protected mode :-). If you mean real mode, it has been done for a year. See another discussion for why it isn't sufficient. >> >Fix the checksum after the AA55 (why isn't this done now?). >OK. Change that to "explain why the Compaq POST routines won't boot >the machine because they checksum the entire boot area including the >partition table and MBR". Then maybe add "Look at the LILO documentation >that actually documents the checksum for Compaq and some other vendors". Compaq doesn't follow the industry standard of no error checking :-). >> >Then from protected mode *always* use the 32 bit sector offset >> >instead of the C/H/S value. >> >> This has been done for a year. >Even for locating the DOS partitions? Yes. Bruce