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Date:      Thu, 07 Oct 1999 10:14:46 -0600 (MDT)
From:      Kevin Vigor <kevin@vigor.nu>
To:        freebsd-hackers@freebsd.org
Subject:   Hello & boot > cylinder 1024 suggestion
Message-ID:  <XFMail.991007101446.kevin@vigor.nu>

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Hello all,

    it's my first time, so please be gentle...

    I'm not sure if this is the right list for this issue
(freebsd-install looks better, but is closed, at least according to the
charter), so please redirect me if necessary.

    I was recently annoyed to find that I cannot install/boot FreeBSD
from a hard drive partition extending beyond cylinder 1024 (not a
problem unique to FreeBSD by any means...). Even with LBA support,
this translates to an 8-gig limit (i.e. the boot partition must be
completely within the first 8 gigs of the hard drive).

    Now that 20-gig & greater drives are commonly available, this
becomes a real and annoying limitation.

    It occurred to me that a potential solution for this problem is to
use an IDE specific interface in the boot process, thus side-stepping
the stone-age BIOS int 13 interface (whence the 1024 cylinder limit
originates). This would involve writing an IDE specific MBR loader (an
adaptation of BootEZ) and adapting BTX similarly. This obviously
doesn't help SCSI users, but does solve my problem nicely.

    I have done some basic hacking and convinced myself that this is
possible using IDE PIO mode (inefficient, but hardly a major concern
for the boot loader).

    This would obviously also require some alterations to the install
process: it would need to detect an IDE interface and then allow
installing the IDE specific boot sectors and installing onto a
partition > 1024.

    So, questions: has anybody thought of this before? I
couldn't find any reference to such a project anywhere, but it seems
relatively obvious. Does this sound like a idea worth pursuing? And
assuming that the previous answers are no and yes respectively, is 
there anyone who can/would assist with the install integration/testing
portion of this (I am confident of my ability to code the MBR/BTX
changes, but much less confident of my understanding on the install
process).

        Peace,
                Kevin


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