Bootstrap question

[surapong singshinsuk]

Hi,
 
During the installation process, there are 3 choices to choose what to install on MBR

1. install boot0 as a bootmanager on MBR
2. install mbr as a standard mbr on MBR
3. install nothing on MBR
 
I've some questions regarding to bootstrap sequence
1. In my understanding,
   mbr is a standard mbr installed on MBR. it jumps directly to marked active slice to load boot2.
   boot0 is a bootmanager installed on MBR. it is used to load boot2 on selected slice.
   boot1 works as mbr but it is used on floppy disk to load boot2.
   boot2 is used to load loader.
 
so excluding cdboot and pxeboot,there are 3 possible sequences to boot FreeBSD
1. mbr -> boot2 -> loader
2. boot0 -> boot2 -> loader
3. boot1 -> boot2 -> loader
Is my understanding correct ?
 
2. During the installation process, I choose "install standard MBR (no boot manager)"
and I later use boot0cfg -B da0 to install boot0 on MBR. Now I want to get rid of bootmanager.

How can I re-install mbr on MBR ?
I tried both of this commands but didn't work

boot0cfg -B -b /boot/mbr da0 
dd if=/boot/mbr of=/dev/da0 bs=512 count=1
 
but I can back up what is on MBR using this command
dd if=/dev/da0 of=/tmp/mbr.bak bs=512 count=1
 
Please enlight me.
Thank You


		
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