Date: Fri, 27 Oct 1995 13:15:53 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: bde@zeta.org.au (Bruce Evans) Cc: msmith@atrad.adelaide.edu.au, terry@lambert.org, hackers@freebsd.org, lenzi@cwbone.bsi.com.br Subject: Re: boot disk.... Message-ID: <199510272015.NAA23839@phaeton.artisoft.com> In-Reply-To: <199510271940.FAA25718@godzilla.zeta.org.au> from "Bruce Evans" at Oct 28, 95 05:40:54 am
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> >Stage 2 boostrap ... > >... should perform MBR fixup to > >guarantee that the absolute offset field in the MBR matches the c/h/s > >values for the slice under the BIOS geometry. > > Only for its own benefit. Drivers don't want to know about yet another > translation. If this is there, then there is NO SUCH THING AS TRANSLATION from the kernel perspecitve. The kernel ignores the C/H/S values, using the 32 bit sector offsets instead (which are now guaranteed to be valid). Almost all translation problems bite the dust. The exception is for non-linear translation (BIOS-based sector sparing, etc.), and then you are screwed on a shared disk in any case unless you can turn it off. You are also screwed unless the disk is used as a naked BSD disk without a DOS partition table/MBR. It works with the BIOS boot code because the cylinder offset on a naked partition is invariant under translation. > >It should also be buildable > >as a DOS program, to allow it to work with Ontrack's Disk Mangler. The > > Nothing should require DOS utilitites to build. Agree. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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