Subject: RE: Booting sd0 (disk geometry versus bios geometry)
To: None <port-i386@NetBSD.ORG>
From: Gunnar Helliesen <gunnar@bitcon.no>
List: port-i386
Date: 07/14/1998 23:33:37
Heiko W.Rupp wrote:
> 
> This all is on an adaptec

Me too. AHA2940UW. Installing 1.3.2.

> I have the possiblity to use the real geometry (which won't work) or
> to use a fake geometry where all five possible coices also don't boot
> afterwards.

I finally gave up and entered 1024/16/63 just for the hell of it. Worked
like a charm, the machine boots just fine. fdisk(8) reports:


******* Working on device /dev/rsd0d *******
Warning: BIOS sector numbering starts with sector 1
parameters extracted from in-core disklabel are:
cylinders=8338 heads=10 sectors/track=213 (2130 sectors/cylinder)

Figures below won't work with BIOS for partitions not in cylinder 1
parameters to be used for BIOS calculations are:
cylinders=17618 heads=16 sectors/track=63 (1008 sectors/cylinder)

Information from DOS bootblock is:
0: sysid 0 (unused)
    start 0, size 0 (0 MB), flag 0x0
        beg: cylinder    0, head   0, sector  1
        end: cylinder    0, head   0, sector  0
1: sysid 0 (unused)
    start 0, size 0 (0 MB), flag 0x0
        beg: cylinder    0, head   0, sector  1
        end: cylinder    0, head   0, sector  0
2: sysid 0 (unused)
    start 0, size 0 (0 MB), flag 0x0
        beg: cylinder    0, head   0, sector  1
        end: cylinder    0, head   0, sector  0
3: sysid 165 (NetBSD or FreeBSD or 386BSD)
    start 63, size 1032129 (503 MB), flag 0x80
        beg: cylinder    0, head   1, sector  1
        end: cylinder 1023, head  15, sector 63


Any reason why this is a bad idea? Any reason why sysinst couldn't just
assume 1024/16/63 for the MBR on all machines with large disks (>503 MB)
in case the user wants to use the entire disk for NetBSD? If he doesn't,
sysinst could just grab the geometry from the existing MBR. In any case
this stuff should be hidden from the user.

BTW, the "real" geometry of the disk as displayed by dmesg(8):


sd0 at scsibus0 targ 0 lun 0: <QUANTUM, VIKING II 9.1WLS, 3506> SCSI2
0/direct f
ixed
sd0: 8709MB, 8338 cyl, 10 head, 213 sec, 512 bytes/sect x 17836668
sectors


Which is the same as the in-core disklabel. The Adaptec is set to
"translation of disks > 1GB".

BTW II: A PII-400/512 MB/UW-SCSI is _really_ fast! ;-)

Gunnar

--
Gunnar Helliesen   | Bergen IT Consult AS  | NetBSD/VAX on a uVAX II
Systems Consultant | Bergen, Norway        | '86 Jaguar Sovereign 4.2
gunnar@bitcon.no   | http://www.bitcon.no/ | '73 Mercedes 280 (240D)