Subject: Re: install/19204: NetBSD/i386 does not support extended partition for the disklabel
To: None <>
From: David Laight <>
List: netbsd-bugs
Date: 12/07/2002 19:30:53
On Mon, Dec 02, 2002 at 11:50:47PM +0000, David Laight wrote:
> I have 1/2 a plan to do an LBA only version that will look
> in the extended partition.
> However it would be easier with different key presses.

Done - I can get the 'not a system disk' message from the
win98 partition in the extended partition (type 0x0f) of my disk.

I need to update fdisk as well as the 'boot' program and the
kernel in order to boot netbsd from an extended partition.
Installation would require the installer be changed as well.
However space in the boot program is no where near as tight
as in the mbr code.

In order to get enough code space I had to remove support
for CHS disk reads, so this won't work on old systems.
(my mbr_bootsel version will).

The layout of the data is the same as the current mbr_bootsel
code.  Extended partition pbr records have to be formatted
to look like the mbr_bootsel mbr (ie have the extra 0x55aa
and four 9 byte name strings).

The user interface has changed slightly, F1, F2 etc boot disks
0 upwards. And 1, 2 etc boot the enabled OS (not the partition

At the moment there are about 20 spare bytes!  Mainly due
to some horrid coding practises [1] (but no self modifying code).

If anyone wants a look goto then netbsd/mbr_lba/mbr_lba.S


[1] like co-routine calls and data bytes following call instructions....

David Laight: