[Gllug] Using external USB drive/stick for OS

[damion.yates at gmail.com]

On Tue, 4 Nov 2008, Dennis Furey wrote:

> On Tue, Nov 04, 2008 at 11:31:20AM +0000, Christopher Currie wrote:
> 
> > If you want the stick to be a genuinely portable OS, then there's
> > much more of a problem, since some laptops won't boot from the USB,
> > and others change drive assignations arbitrarily. I solved this with
> > the Grub CD idea, but even that doesn't work on all PCs.
> > 
> > Maybe someone has solved this problem in the year or so since I
> > looked at it, but if so it's news to me.
> 
> Yes someone has, as explained here.
> 
> http://feraga.com/node/94

This solves the problem of devices moving around arbitrarily.

It does not solve the massive array of issues with trying to boot PCs:


Lack of control over boot order in rare BIOSes or ones where you don't
have the password.

Limited options, ie only floppy or HD, maybe cdrom.

Old "El Torito" 1.4MB limitation - this remains an issue on some systems
that can USB boot.

limited initrd/initramfs size (relates to above), so you can't include
all drivers for the cdrom/usb you're booting from so you can't continue
an install or boot.  Or can't see the main HD for swap and potentially
the main reason to boot via tmp means in the first place.

Proprietory drivers for the scsi HD subsystem you're booting from, and
too much sandal-wearing-tree-hugging-ness from your distribution of
choice (hello debian) to even consider letting you include it.

Old LBA vs normal geometry causing your partitions to not quite match
up.

EFI partitions not matching MBR style.

Multiple standards for netbooting, not quite consistant or clean tftp
compatibility.

No USB support for usb keyboard so you can't ^C if it's booting the
wrong OS.  No ^C option for netboot, so you have to wait 30seconds for
timeout.  No working framebuffer mode for the screen so boot goes
invisible.


These are just ones from the top of my head, and to be honest things
have gradually got a bit better over the years.  All of these have
solutions on a case by case basis and distribution creators have enjoyed
solving all of them.  -  Typically now, a PC will boot a grubbed USB
stick and your only problem is selecting a dist and packages that fit in
the limited space.

Nobody today has ever got a one size fits all boot system which is
guarenteed to work on any hardware you come across.  You do get some
very good attempts like Knoppix, but even this fails on some boxes,
dropping you at a very spartan initramfs busybox shell (which in some
cases was enough for me to be able to boot, but then I'm good ;)).

EFI might help.  I don't hold out much hope.

On my todo list is to build a 1.4MB super booter Linux dist, which
contains KBOOT for booting a further kernel (as the PS3 uses), and has
just about every driver you can imagine so you can get to the point of
seeing the devices to load the read OS and kernel you want to.  Like a
protected mode and more powerful grub, designed to fit to El Torito
limitations.

I love this area :)


Damion
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