Date: Thu, 24 Aug 1995 09:36:14 -0700 From: "Jin Guojun[ITG]" <jin@george.lbl.gov> To: ywliu@beta.wsl.sinica.edu.tw Cc: bugs@freebsd.org Subject: Re: Why FreeBSD cannot boot from fdisk partition 4 Message-ID: <199508241636.JAA06213@george.lbl.gov>
next in thread | raw e-mail | index | archive | help
>>Your are right. If I start the 4th partition before 540MB, then it will be
>>bootable. I wonder if this can be fixed in Release 2.1.
>
>Never will it be. It's the limitation of BIOS, rather than FreeBSD itself.
>Other 32bit OSes, such as OS/2, suffer from the same limitation too. The
>OSes themselves can exceed the 1024 limitation by bypassing BIOS without
>any problems, but when the OSes booting, it usually is the BIOS does the
>job.
>
>I believe FreeBSD only wants you to put root partition, where the OS image
>sits, before 1024 cylinder; all other partitions can be anywhere. Maybe
>you can try to reformat you HD with Large or LBA mode turned on in your
>BIOS setup to give it a try (at the expense of losing all data). I barely
>remember FreeBSD supports LBA mode.
Oops, the number is wrong. It is not before 540MB, it is before 265MB.
Any physical partition 2-4 (I would say virtural disks 2-4 to avoid confusion
with UNIX partition) if allocated before 240MB, the FreeBSD won't boot from it.
I had three types of disks, and they are all 850MB -- Western Digital,
Maxtor, and Conner. The physical specs are same:
1654 Cylinders, 63 sec., and 16 heads
When I moved FreeBSD to third virtural disk (wd0s3), it actually started at
240MB. After I delete all virtural disks, created a DOS partition on
virtural disk 1 (FreeBSD calls it wd0s1) with 240 MB, and created a second
virtural disk for FreeBSD. The FreeBSD boots OK.
It can boot until the previous partition (virtual disk 1) size reaches 265MB.
At this point, the cylinder is under 540. So, is Boot Manager or FreeBSD
problem?
It looks like a FreeBSD problem. I made wd0s1 for Linux and uses 280 MB space.
Then, I created second partiton wd0s2 by using the rest space 537MB.
DOS installed on the second partiton boots fine. However, If installing
FreeBSD on the second partiton, then it won't boot. That is, FreeBSD cannot
boot after 265 MB on a hard disk. The problem is the boot block is not installed
correctly. When booting, it still says: "Starting MS-DOS" and hang.
There is no more MS-DOS since FreeBSD has installed on the partition.
/-------------- Jin Guojun ------------ v ---- Internet: g_jin@lbl.gov ----\
| Imaging & Distributed Computing | Usenet: ucbvax!g_jin@lbl.gov |
| Lawrence Berkeley Laboratory | Bitnet: -- |
| 50B-2239, Berkeley, CA 94720 - jin%george.lbl.gov@Csa3.LBL.Gov |
\--------------------------------------------------------------------------/
P.S.
For FreeBSD team:
Please let me know if I am right or wrong. If this is true and you
need me work on solving it, I will be happy put my hand on.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199508241636.JAA06213>