# convert OpenBSD mbr to FreeBSD mbr with FreeBSD boot manager



## sidney6 (Jul 18, 2011)

I have freebsd 8.2 and openbsd 4.9 on the same disk and openbsd's boot code is in the mbr.  I would like to use freebsd's boot manager.  The handbook says to use:


```
fdisk -B -b /boot/boot0 /dev/ad0
```

It prints the bootlabel; I tell it to change the bootcode; it replies:


```
Figures below won't work with bios for partitions not in cyl 1
```

I don't know what that means.  It prints the bootlabel again; I tell it to write the new partition table; it replies:


```
fdisk: Class not found
fdisk: Failed to write sector zero
```

So my pc lacks the "class" to use freeBSD's boot manager.  What does that mean?

note:
I put freebsd / in slice one, openbsd in slice two and the rest of freebsd in slice 3, in order to keep boot files accessible.

sid


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## wblock@ (Jul 18, 2011)

I don't know why it says "Class not found", but have ignored it without problems.  Back up first, of course.

Writing to the MBR is disabled until you turn off the safety:
`# sysctl kern.geom.debugflags=16`


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## sidney6 (Jul 18, 2011)

Thanks, that did it.

Figures, after all, a good os is like a handgun without safety instructions, ...without someone to tell you how to use it, you're lucky just to have 10 toes left.

sid


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