Re: bootable disk: how?

[David Laight <david%l8s.co.uk@localhost>]

On Thu, Apr 17, 2008 at 01:24:46PM -0400, der Mouse wrote:
> Okay, I give up.  What does it take to make a disk bootable?

Installing all the required bootstrap code into all the correct places :-)

> I thought I knew.  But either I'm wrong or the tools aren't doing what
> I thought they were (and, if I'm reading things right, what they're
> documented as).
> 
> I've used fdisk -aui and answered y to the "update the bootcode"
> prompt.  I've used installboot to update the second-level bootlocks.
> I've even tried disklabel -B (this started on a 3.0 system).  Nothing
> works.
> 
> Most recently, I moved the disk to a 4.0 machine and used fdisk -aui
> and installboot there.  It *still* fails to find an OS.  (The exact
> message differs from system to system, depending on the BIOS; the 4.0
> machine says "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER",

That message usually comes from the M$ sector zero code on non-bootable
disks.

> while the 3.0 machine says "Operating System not found".

That might be from the netbsd mbr code, I can't remember the exact text.

Thing to check:

1) Sector zero of the disk contains the correct mbr code (eg /usr/mdec/mbr)
2) Sector zero of the partition (63 of the disk) contains the bootxx
   code (eg /usr/mdec/bootxx_ffsv1). This contains a gap for the netbsd
   disklabel
3) /boot exists
4) the kernel exists

fdisk -c will fix (1) and installboot (2)
Possibly something is confused in the CHS/LBA mapping, using mbr_ext
will force LBA disk reads.

The recent netbsd boot bits all output a message, but maybe 4.0
doesn't contain that version.

        David

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