Re: bootable disk: how?

[der Mouse <mouse%Rodents.Montreal.QC.CA@localhost>]

>> Okay, I give up.  What does it take to make a disk bootable?
> Installing all the required bootstrap code into all the correct
> places :-)

How helpful. :-)

>> 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.

Not quite that simple.  (1) the message changes depending on which
machine the disk is in, so it's not just coming from bootcode on the
disk; (2) while I haven't done it for the DISK BOOT FAILURE message, I
searched the first something like 64K of the disk for the "Operating
System not found" message; it ain't there.

> 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

4 isn't the problem; I'd get the booter prompt, at least, if that were
what were wrong.

> fdisk -c will fix (1) and installboot (2)

See my recent message in response to Brian Buhrow.

> Possibly something is confused in the CHS/LBA mapping, using mbr_ext
> will force LBA disk reads.

Hmm.  Could this be related to the "can't determine number of heads"
message?  (See the message referred to above.)

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