On Wed, Apr 26, 2006 at 04:26:45PM -0400, Brian A. Seklecki wrote:
> 
> Boot process question:
> 
> At line 446 in mbr.S, error "No opearting system".  According to mbr(8):
> 
>      3 No operating system     The bootsector was loaded successfully,
>                                but it was not valid (i.e., the magic num
>                                ber check failed, or it contained no
>                                code).
> 
> 
> To expound on this, the MBR code was able to:
> 
> 1) find and select active partition, but...
> 2) but unable to read the boot block in the first sector?
> 
> "boot block" referering to /usr/mdec/bootxx_* installed into first slice?
> 
> Possible causes would be an invalid partition table?

Actually 'The first sector of the partition was read, but the last two
bytes weren't 0x55 0xaa or the first byte was 0x00'.

If you are trying to boot netbsd, you need to run installboot.

It could happen if the bios lies about the disk geometry, but mismatches
between the mbr table and the bios (eg caused by moving the disk to a
system where the bios uses a different geometry) are detected and LBA
reads done instead of CHS ones.

I usually run 'hd -C -n 512 /dev/wd0a' to check the contents....

	David

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