Remove GRUB?

[Michael Dexter]

>>I was experimenting with the GRUB bootloader and would now like to 
>>remove it. Something went wrong and I must now use a bootable CD 
>>that gives me an option to "boot to the first partition" and the 
>>system boots fine.
>>
>>man bsdlabel gives:
>>
>>Installing Bootstraps
>>      If the -B argument is specified, bootstrap code will be read from the
>>      file /boot/boot and written to the disk.
>>
>>Assuming that this affects the mbr of the who drive, I tried:
>>
>>localhost# bsdlabel -B /dev/ad0
>>localhost# bsdlabel: /dev/ad0: no valid label found
>>
>>No problem, let's try the root partition:
>>
>>bsdlabel -B /dev/da0s1a
>>
>>No error, it blinked the hard drive activity light and appears to 
>>have done something but alas, it still reports a GRUB error 21 
>>rather than given any sign of the FreeBSD loader.
>>
>>Any pointers to the rescue/install procedures applicable to this?
>
>Did you use fdisk to check and see if the first slice is marked as 
>active? Here's a sample from one of my systems:
>
>Media sector size is 512
>Warning: BIOS sector numbering starts with sector 1
>Information from DOS bootblock is:
>The data for partition 1 is:
>sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
>     start 63, size 10474317 (5114 Meg), flag 80 (active)
>         beg: cyl 0/ head 1/ sector 1;
>         end: cyl 651/ head 254/ sector 63
>The data for partition 2 is:
>sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
>     start 10474380, size 10458315 (5106 Meg), flag 0
>         beg: cyl 652/ head 0/ sector 1;
>         end: cyl 1023/ head 254/ sector 63
>The data for partition 3 is:
><UNUSED>
>The data for partition 4 is:
><UNUSED>
>
>note the flag 80 in the first entry.

The results appear similar:

localhost# fdisk ad0
******* Working on device /dev/ad0 *******
parameters extracted from in-core disklabel are:
cylinders=155061 heads=16 sectors/track=63 (1008 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=155061 heads=16 sectors/track=63 (1008 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
     start 63, size 81915372 (39997 Meg), flag 80 (active)
         beg: cyl 0/ head 1/ sector 1;
         end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
sysid 131 (0x83),(Linux native)
     start 81915435, size 61432560 (29996 Meg), flag 0
         beg: cyl 1023/ head 255/ sector 63;
         end: cyl 1023/ head 254/ sector 63
The data for partition 3 is:
sysid 130 (0x82),(Linux swap or Solaris x86)
     start 143347995, size 12948390 (6322 Meg), flag 0
         beg: cyl 1023/ head 255/ sector 63;
         end: cyl 1023/ head 254/ sector 63
The data for partition 4 is:
<UNUSED>
localhost#

On a related note, once working, how does one configure the FreeBSD 
loader to give the Linux partition as an option? It seems to have 
happened "automagically" in the past.

Thanks,

Michael.