Subject: Re: big IDE disks
To: Gordon Ross <>
From: Matthew Barry <>
List: current-users
Date: 12/30/1994 20:58:57
> The geometry you specify to pfdisk needs to match what the BIOS
> gives to the first-stage boot program, otherwise the boot program
> will get the wrong sectors when trying to load the second-stage boot
> program.

> When you start pfdisk and give the "L" command (list) it will show
> you what the BIOS told it the geometry is (should be fine).  I made
> it possible to override the geometry mostly so I could do testing
> with a plain file instead of the master boot record.  You should not
> override the geometry unless you know your second-stage boot program
> will be able to deal with the somewhat messy result.

> I suggest you just partition the 524 cylinders the BIOS thinks are
> available into something convenient for you: (i.e. type this at
> pfdisk)

	1    6   0   127  MS-DOS
	4 0xA5 128   523  NetBSD
	a 4

I tried this, but NetBSD correctly detects that the disk is 2100c 16h
and 63s. During disk partitioning the sysmts calls fail. I get quite a
lot of errors from the process and the DOS BIOS record is wiped out.

> By the way, the pfdisk that most people got from was
> an incomplete version, missing the documentation, boot files, and
> sources for other systems.  The FreeBSD folks said they would fix
> it, but for now you can get the whole package from:

	cd /pub
	get pfdisk-1.3.tar.gz

> Lastly, I wrote pfdisk a very long time ago, and I don't really use
> DOS much these days, so please forgive my lack of current expertise
> on using pfdisk to make DOS live with *BSD...

I got your latest version and compiled it for unix (SYS=i386) would
not work. It wrote a boot record, which NetBSD liked. However the DOS
record was not over-written and when the system booted it did not see
the NetBSD version.

I think the problem is that I have some form of enhanced IDE
controller. This is surmise, rather than knowledge, as I do not need
any drivers to use the full disk under DOS or windows. Of course such
drivers may be part of the the standard installation for all I know. I
certainly did not receive any extra software with my disk.

Thank you for your assistance. Any further suggestions would be
greatly appreciated.