Date: Fri, 5 Jan 1996 18:56:16 +1100 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, terry@lambert.org Cc: freebsd-hackers@freebsd.org, jkh@time.cdrom.com, obrien@cs.ucdavis.edu, phk@critter.tfs.com Subject: Re: X for install Message-ID: <199601050756.SAA16788@godzilla.zeta.org.au>
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>> >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=<device> 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
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