[Oberon] Bluebottle and qemu

Jack Johnson knapjack at gmail.com
Thu Oct 28 04:04:52 CEST 2004

On Tue, 26 Oct 2004 20:24:13 -0700, Jack Johnson <knapjack at gmail.com> wrote:
> I'll let you know how I managed.


OK, in my particular instance, I took a 4GB disk and erased all the
partitions.  I did a nice, standard Bluebottle install, creating a
258MB 1st partition, setting it active, and following the steps from
the installation text.  I did *not* install the Bluebottle boot

Then, I installed Ubuntu Linux, a nice Debian variant.  I let it use
the remaining free space and install GRUB as the bootloader.  Then I
installed QEMU.

Now, we need to let GRUB know that Bluebottle can be booted.  It's
much like dual-booting Windows, and GRUB makes this easy, so I just
added a few lines to /boot/grub/menu.lst:

	title           Bluebottle Oberon
	root            (hd0,0)
	chainloader     +1

and I tested a reboot, which works fine, and I can dual-boot into Bluebottle.

Now, Ubuntu uses QEMU version 0.5.5, so your command line switches may
vary.  I want Oberon to boot from the same hard drive as my Linux
installation (even though this may be dangerous according to the
documentation -- I suspect it's fine given that we're using a separate
partition).  But, QEMU wants the drive parameters in LBA format, so I
need some info from my drive first:

	jack at tlon:~ $ sudo fdisk /dev/hda

	Command (m for help): p

	Disk /dev/hda: 4325 MB, 4325529600 bytes
	255 heads, 63 sectors/track, 525 cylinders

If the number of heads is 255, I know that I need to do some math.  To
turn this cylinder, head, and sector data into LBA format I take the
number of heads and multiply it by the number of cylinders, then
divide by my "new" LBA head count of 16 and round down:

	525 * 255 = 8367.1875 * 16

so now I feed my "new" cylinder count of 8367 to QEMU.  I need root
access to the hard drive device so I can write disk changes, and both
Ubuntu and I like sudo, so:

	sudo qemu -hdachs 8367,16,63 /dev/hda

and voila, I'm booting Bluebottle inside QEMU inside Linux, and I can
dual-boot either OS.  Which is great, because this particular
workstation has an unsupported NIC, and I've run out of pennies.

Good luck!


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