newfs_msdos behaviour change between 4.x and 5?

Geoff Buckingham geoffb at
Fri Apr 23 06:22:37 PDT 2004

On Fri, Apr 23, 2004 at 08:44:16PM +1000, Bruce Evans wrote:
> The test partition was at offset 6.1GB on an old 6.4GB disk.  But 6.4GB
> disks are new compared with DOS 4.01.  I think DOS 4.01 doesn't understand
> disks larger than 2GB.  Its fdisk starts printing negative and truncated
> (modulo 1 or 2G) values for partitions beyound 1 or 2GB.  I think DOS
> 6.22 is supposed to work up to 8GB, but it didn't seem to on my test
> partition.  Its fdisk sort of understands partitions beyond 8GB -- it
> reduces to the 8GB boundary instead of blindly truncating values modulo
> the boundary.

When does dos gain FAT32 support? HP documentation for their SmartStart
scripting toolkit seems to suggest there is something special about their fdisk 
(cpqdisk) and format (cpqfmt) in that they can create 4GB FAT 16 partitions.
(You need FAT 16 to script installing NT4 which doesn't understand FAT32)

I have never figured out what they do differently from dos, maybe they can
just address more sectors. 

I have found that providing I scrape dmesg for the disk geometry information
I need I can create bootable Win95 SR2 fat32 partitons of 4GB, either offset
spt from the begining of the disk or behind a compaq system partiton.

Maybe newfs_msdos should just require heads, spt and offset/hidden to be
provided if installing a boot block?

fdisk on my cut down cd boot of 5.2.1 seems to have a dependancy for 
determining disk geometry I have not fullfilled as it allways assumes 
1C/1H/1S and has to be told otherwise.  

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