problem with 1024 cylinders

Henrik W Lund henrik.w.lund at
Wed Sep 15 13:25:37 PDT 2004

fancalenno wrote:

>I have one IDE disk drive with 40GB
>I used the partition utility of win xp to make three partitions when I was installing winxp.  Its sequence is pri(xp)->ext(xp)->pri(bsd).
>I installed the xp on the first partition(pri) and put some personal data on the next partition(ext).
>In the partition editor, I deleted(d) the third partition(pri) that I had made, then created(c) a new BSD partition.
>Three partitions occupy 8GB. 16GB. 14GB in sequence respectively.
>After testing, both of win xp and FreeBSD can run normally with no problem.
>my question is ... does the FreeBSD still have the restriction that its root file system must be installed in the first 1024 cylinders???
>the document as above point out should put the root file system / into the 1204 cylinders of the first disk drive otherwise bsd can't start normally.
>The book" FreeBSD: An Open-Source Operating System for Your Personal Computer" by Annelise Anderson  say "FreeBSD needs a few of its files(those in the / or 'slash' root file system)close enough to the front of the drive so the computer can find them. And every other operating system needs some files up front too..."
>I used partition magic to see the cylinder range of my bsd partition.  It indicated the cylinder range of bsd had already gone beyond the 1024 cylinders! 
>But I still can use booteasy to start both of these two os.   So I can't figure out if the FreeBSD was really restricted by the 1024 cylinders???
>I think if it's about boot manager???
>The common boot manager uses BIOS to start the os, but it's also restricted by BIOS.
>The BIOS has the restriction that os can't be start if some files of os(just as / of bsd)go beyond 1024 cylinders.
>But the booteasy doesn't use the BIOS, so it's not restricted by BIOS?
>I had ever used OS-BS to boot these two os, the xp can start normally but the BSD can't. The pop up prompt window say"NO OPERATING SYSTEM!".   So I can't make sure if the factor"boot manager use BIOS or not" affects the 1024 cylinders?

I think this is a rather nifty feature of the FreeBSD bootloader (the
infamous boot0). It can boot anything from anywhere on any disk (someone
correct me if I'm wrong here, please), provided that what it boots wants
to boot from where it's situated. I know WinXP expects to have its
startup files on the first partition on the first physical disk and
refuses to start up otherwise, other OSes may have similar quirks. But
from what I gather, FreeBSD is quite forgiving in this regard.

If someone more knowledgeable would care to elaborate (or, quite
possibly even more likely, correct me), please do.

-Henrik W Lund

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