Booting FreeBSD-5.3 from NTLDR

[Mark Ovens]

Rakhesh Sasidharan wrote:
> On Mon, 31 Jan 2005 11:33:59 +0000, Mark Ovens <marko at freebsd.org> wrote:
>> I rewrote that section of the FAQ years ago (around FreeBSD 3.1!!)
>> because the previous wording was unclear and I did _exactly_ what
>> Rakhesh has done :-(
> 
> Ah! Glad to see I am not the only one. :))) Felt really goofy when I
> read that this goofup that I did was clearly documented in the
> handbook! Thankfully I had backups (I keep doing this sort of messups
> every now and then :p) and so I wasn't too freaked out when I
> discovered my entire partition table and boot sectors erased -- but it
> wasn't a nice sight either. The thought of re-installing everything,
> plus restoring from backups, yada yada yada ... thankfully I managed
> to find a program for recovering the partitions.
> 

Hehe! I did it the hard way; I manually recreated the partition table - 
3 partitions! In fact.....[roots around in drawer]......yes, still got 
the printout of the spreadsheet I used to calculated the start and end 
CHS values - don't know why, the disk was replaced ages ago :-)

>> Caveat: Things have no doubt changed since then so it may now be
>> possible to add FreeBSD to the NTLDR menu with FreeBSD on a different
>> disk, but I've never investigated it as I am happy with the solution I use.
> 
> Actually, I know that I can very well use GRUB or BootEasy to do this
> job. But I dunno, its this curiousity that has gotten over me -- to
> explore NTLDR a bit more, and to see why I can't boot into FreeBSD
> with it. If I had gotten a definitive answer that its *not* possible,
> then I would have given up -- but as it is, nobody has said its not
> possible, and added to that I can see if I extract the bootsectors
> using a program like BootPart then things work, and so I am highly
> curious why I can't get things working with conventional tools and
> methods like "dd" etc! Guess if I get no answers, I'll just start
> using BootEasy, but I'm curious why things dont work nevertheless. :))
> And I'm all the more curious what changes BootPart makes to the
> extracted bootsectors to make them work with NTLDR.
> 

IRCC, boot0 is the MBR and boot1 is the boot sector (of the FreeBSD 
partition (slice)) and they only ontain info about the local disk, i.e. 
_relative_ info in effect, so if FreeBSD is on your second disk and you 
copy boot1 to C:\BOOTSECT.BSD and add an entry for it in BOOT.INI then 
NTLDR has know way of knowing that it refers to the second HDD and so 
can't boot because the info doesn't match the layout of the first HDD. 
Remember boot0 and boot1 are restricted to 512bytes - one sector. That 
is the reason as far as remember.

Mark


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