Booting FreeBSD-5.3 from NTLDR

Rakhesh Sasidharan rakhesh.s at
Mon Jan 31 02:16:29 PST 2005

Thanks for that link! I had read that part of the handbook a long time
ago, and that's how my ideas of boot0 and boot1 and etc etc had gotten
clear. Glad to see it once again -- in the context of my question! :))

So what I understand now is -- copying boot0 over to c:\bootsect.bsd
will *not* work. Which explains why my MBR got messed up when I tried
booting FreeBSD this way. :(

But I'm still confused. How do I install boot0 using sysinstall? As
far as I remm, sysinstall gives three options -- (a) leave the MBR
untouched, (b) put a standard MBR, and (c) install BootEasy. My
understanding is that option (b) copies boot0 to the MBR, and this
that is what I had chosen while installing FreeBSD. How does one copy
boot0 to a file using sysinstall??

On Mon, 31 Jan 2005 08:44:23 +0000, Mark Ovens <marko at> wrote:
> Rakhesh Sasidharan wrote:
> >> No, boot0 is just a normal file that is 512 bytes long.  There is
> >> nothing special about it.  In it is a bootloader program that can be
> >> used to boot FreeBSD, and if you run it during boot, it will read the
> >> partition table and look for all OSes.  I think it will modify the
> >> partition table, though, marking the last OS you booted into, but that's
> >> the program running doing that, the file itself is harmless.
> >
> > Ok. I must have used some other command then, which resulted in my
> > first disk MBR getting over-written ... strange. :-/
> >
> > By the way, does the fact that NTLDR is on my first disk, while
> > FreeBSD (and hence its MBR boot0) is on my second disk complicate
> > matters? I mean, you mention boot0 will modify my partition table to
> > reflect which OS was booted last -- will it by any chance modify the
> > partition table on the first disk and hence mess it?
> >
> >
> Yes and yes,
> Regards,
> Mark
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				-- Rakhesh
				   rax at

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