On Mon, Jul 15, 2002 at 11:03:21AM +0100, Rasputin wrote:
> 
> I've been toying with using mbrlabel to make my (unused)
> win98 partitions readable.

Not sure what you mean by that....
If you want netbsd to be able to use the space just edit the
netbsd disklabel (with disklabel).

> STr last time I did this I got an unbootable drive, and someone
> mentioned I should reinstall the boot blocks after running fdisk?
> 
> If I wanted to do this, I'd run
> 
> /usr/mdec/installboot /usr/mdec/biosboot.sym /dev/rwd0a
> 
> correct?

fdisk doesn't go anywhere near anywhere that /usr/mdec/installboot 
will write to.

> 
> Now, since this is writing to the root filesystem (I think),
> how would I go about rewriting the boot selector
> (which looks like it's in the MBR someowhere).

fdisk -c and/or fdisk -B
> 
> mbr(8) seems to confirm this, but doesn't explain how to reinstall it.

i386 has more layers of bootstrap than I've cooked hot dinners :-)

The 'mbr' code in sector 0 of the disk is loaded by the BIOS.
The fdisk program modifies sector 0.
The mbr will load the 'pbr' code from first sector of a partition
and execute it.

The 'pbr' code re-reads itself (because it is larger than one sector, and
the mbr code only reads the first sector) then loads in the 'boot' program
from a list of sector numbers.

The boot program does the 5 second countdown.... and loads /netbsd.

/usr/mdec/installboot writes the pbr code, puts the boot program
into /boot and writes the sector numbers of the boot code into the
pbr code.

Clear as mud yet?

	David

-- 
David Laight: david@l8s.co.uk