Date: Wed, 10 May 1995 23:40:37 +0100 From: Mark Valentine <mark@linus.demon.co.uk> To: current@FreeBSD.org Subject: problem with new biosboot? Message-ID: <199505102240.XAA00336@linus.demon.co.uk>
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> phk 95/05/07 19:03:03
>
> Modified: sys/i386/boot/biosboot disk.c
> Log:
> Make disk.c smart enough to handle disk with "OnTrack Disk manager".
> Make it complain if people try to boot from a partition which extends
> past 1024 cylinders. This is better than a random reset...
Since these boot blocks now tell me that my "partition is out of reach from
the bios", I guess I'd better try to understand what might be wrong with my
slice/partition configuration. However, I can't follow the code...
/* This little trick is for OnTrack DiskManager disks */
boff = dl->d_partitions[part].p_offset -
dl->d_partitions[2].p_offset + sector;
/* This is a good idea for all disks */
bsize = dl->d_partitions[part].p_size;
bend = boff + bsize - 1 ;
if (bend / spt > 1024) {
printf("partition is out of reach from the bios\n");
return 1;
}
Why is dl->d_partitions[2].p_offset meaningful even if I don't have OnTrack
DiskManager? Why can't my partition be >1024 cylinders?
The disk in question is a 1GB SCSI (Quantum PD1050iS), attached to an AHA1542C.
# fdisk /dev/sd0
******* Working on device /dev/sd0 *******
parameters extracted from in-core disklabel are:
cylinders=2448 heads=12 sectors/track=69 (828 blks/cyl)
Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=2448 heads=12 sectors/track=69 (828 blks/cyl)
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 0 is:
<UNUSED>
The data for partition 1 is:
<UNUSED>
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
start 0, size 50000 (24 Meg), flag 80
beg: cyl 0/ sector 1/ head 0;
end: cyl 1023/ sector 63/ head 255
The geometry is the untranslated version. The bogus slice isn't what I
remember setting it up as when I upgraded to FreeBSD 2.0 (950210 SNAP),
but probably happened when I used disklabel -e to specify non-zero RPM,
etc. (?) I used what I thought was a correct sizing based on the
translated geometry at that time.
Curiously, the compatibility device shows me an MBR table with the translated
geometry:
# fdisk /dev/sd0d
******* Working on device /dev/sd0d *******
parameters extracted from in-core disklabel are:
cylinders=1003 heads=64 sectors/track=32 (2048 blks/cyl)
parameters to be used for BIOS calculations are:
cylinders=1003 heads=64 sectors/track=32 (2048 blks/cyl)
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 0 is:
<UNUSED>
The data for partition 1 is:
<UNUSED>
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
start 0, size 50000 (24 Meg), flag 80
beg: cyl 0/ sector 1/ head 0;
end: cyl 1023/ sector 63/ head 255
Which of these is relevant, and where on the disk is the other one stored?!
My disklabel uses translated geometry:
# disklabel -r sd0
# /dev/rsd0c:
type: SCSI
disk:
label: MBR based label
flags:
bytes/sector: 512
sectors/track: 32
tracks/cylinder: 64
sectors/cylinder: 2048
cylinders: 1003
sectors/unit: 2055096
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0 # milliseconds
track-to-track seek: 0 # milliseconds
drivedata: 0
8 partitions:
# size offset fstype [fsize bsize bps/cpg]
a: 36864 0 4.2BSD 1024 8192 16 # (Cyl. 0 - 17)
b: 81920 36864 swap # (Cyl. 18 - 57)
c: 2055096 0 unused 0 0 # (Cyl. 0 - 1003*)
d: 2055096 0 unused 0 0 # (Cyl. 0 - 1003*)
e: 102400 118784 4.2BSD 1024 8192 16 # (Cyl. 58 - 107)
f: 512000 221184 4.2BSD 1024 8192 16 # (Cyl. 108 - 357)
g: 1024000 733184 4.2BSD 1024 8192 16 # (Cyl. 358 - 857)
h: 296960 1757184 4.2BSD 1024 8192 16 # (Cyl. 858 - 1002)
I thought maybe partition 'a' shouldn't be at offset 0, but a fresh
trial installation on wd0 (again of 950210-SNAP, using the whole disk
for FreeBSD) also had this (no manual tweaking on that one).
I thought I was beginning to understand all this, and I'd been running
without problems for a few months (last disklabel -B sd0 was just after
the last change to biosboot before this one). Any pointers as to what
I'm not taking in?
Cheers,
Mark.
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