[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: chainload into a logical partition ?

From: walt
Subject: Re: chainload into a logical partition ?
Date: Mon, 21 Jan 2008 12:25:49 -0800
User-agent: Thunderbird 3.0a1pre (X11/2008012104)

Manfred Knick wrote:
With legacy GRUB, I had experienced serious problems chainloading into a
logical partition:

---->     http://forums.gentoo.org/viewtopic-p-4757849.html

Can you point me to my source of misunderstanding?

You understand that chainloading linux is not necessary, of course.  You
can use grub to do the chainloading if you really want to, but you must
actually install grub *twice*:  once on the master boot record of your
hard drive, and *again* on the so-called boot-record of the linux logical

The reason this works is that the first instance of grub (on the MBR)
then proceeds to chain-load *itself* from the boot record on the logical
partition.  That is, you will see two grub menus during the boot instead
of the usual single menu.  Completely nonsensical because you added the
second boot loader for no reason -- you do see that, right?

Now, the BSD's are more complicated because their booting method is
quite different.  FreeBSD/DragonFlyBSD use their own loader cleverly
named /boot/loader.  Grub will accept /boot/loader as a *kernel* and
you should tell grub to treat it thus.  That's why chainloading is
not needed for those two BSD's, either.

The BSD's all install a 'disk label' which they use the same way that
Windows and linux use the "DOS" partition table.  NetBSD and OpenBSD
each install *one* disk label for each physical drive, and then sub-
divide the physical disk into partitions by reading the disk label.
Free/DragonFlyBSD install their disk labels on the partition where
you install them, instead of the beginning of the disk like the
other two.

BE CAREFUL installing that disk label because you can very easily
overwrite your MBR *and* your DOS partition table at the same time!

Keep a copy of your MBR saved/written down while installing any BSD
because you *will* screw it up -- probably more than once.

None of the BSD installers are configured to install to a logical
partition, BTW.  I do run Free/DragonFly from logical partitions,
but I had to copy them from a primary partition after installation.

Anyway, you can chainload all of them if you want to, because they
all can (optionally) install a boot-record for grub to use -- but
you really need to be careful not to overwrite your MBR!  You have
been warned :o)

Or is this a shortcoming of the grub legacy (0.97) implementation?
- If yes: Has this functionality been implemented / tested in GRUB 2 yet?
- - - - - - If yes: Is GRUB 2 to be considered as stable for production
use yet?

reply via email to

[Prev in Thread] Current Thread [Next in Thread]