GRUB, MBR and NTLDR confusion

[Alan McKinnon]

On Thursday 25 May 2006 17:27, Gary W. Swearingen wrote:
> Alan McKinnon <alan at linuxholdings.co.za> writes:
> > Grub can be installed on the MBR of a disk, or the boot sector of
> > a partition. What you want is to install it to the MBR of
> > /dev/hda.
> >
> > Do not try and make NTLDR the primary boot loader - that way lies
> > madness.
>
> (Side comment: whatever NTLDR is, it's not the primary boot loader;
> that's whatever code is (or maybe just begins, in the case of grub)
> in the MBR.  On most PC's it's the little program in the MBR which
> boots the secondary boot loader in the partition marked active.)

You're right, NTLDR is not a boot loader, it's perhaps best described 
as a kernel loader. I called it NTLDR in haste as I have no idea what 
Windows calls the thing it puts in the MBR.

> (Second side comment: It's "try to", not "try and".)

Correct again :-)

> Please explain why using NTLDR is madness.  I'd think a MSFT
> supporter might want to reserve the MBR for MSFT code to abuse as
> much and as often as it will.  Then configure the MSFT boot loader
> to boot Grub or Linux or whatever off some non-MSFT partition.  If
> the MSFT code too stupid to boot a partition's boot code (eg,
> grub), it can surely boot Linux.  No?

There was a discussion on this list a month ago about that. One person 
claimed it could be done but didn't say how to do it, only that the 
solution was somewhat perverse. Windows boot code does not recognise 
the existence of non MS OSes which makes life difficult in dual boot 
scenarios. It's so much easier to use a solution that is fully and 
clearly documented and that can be relied on to work.

To reply to your question, the MSFT boot loader is most unlikely to 
ever boot Linux. It would need to read and understand ext2, ext3 and 
reiser at a minumum to know where the kernel was, either at boot time 
in the style of a grub stage 1.5, or install time in the style 
of /sbin/lilo.

A simple chain load mechanism is the best we could hope for from the 
MSFT boot code - read and execute the boot sector on an arb partition 
selected by the user from a boot menu. However, does it do this? Can 
it do this? I have never seen or heard of anything that suggests this 
apart from the one case above. I prefer to go with the 
well-documented, understandable solution that grub provides.

-- 
If only me, you and dead people understand hex, 
how many people understand hex?

Alan McKinnon
alan at linuxholdings dot co dot za
+27 82, double three seven, one nine three five