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Re: booting with grub to /dev/sda



Jeff Vian wrote:

On Mon, 2005-01-03 at 12:36 -0700, Jim Cromie wrote:


Jim Cromie wrote:



IOW - its not even seeing /dev/sda, so autocompletes right past that choice.
ANY IDEA WHY ?


solved
writing to someone else almost always helps
- even iff you dont send, ie wait long enough..

I just added '(hd1)  /dev/sda'  to /boot/grub/device.map,
now it shows up on the grub-console,
testing actual boot next.




Naturally - I spoke too soon.. :-/
while grub-console sees it,
it does not on reboot.
when I edit the boot-config to force it, it tells me drive doesnt exist.
when I just select that boot-config, it tries, but errs out
err 21 iirc,
press anykey to continue...
then back to boot-config-choice screen

One other problem there.

Using grub (as you are) presupposes that grub is installed on the boot
disk, and that the boot device is able to tell the system to boot from
the usb device. It also implies that usb drivers have been loaded to
allow this to happen at boot time, before the OS is loaded.



Ive always been less than certain about my understanding of grub,
and for obvious reasons, reluctant to experiment ...

when you say 'installed on boot disk', I have several ways to interpret that:
1. grub-stage1 is in the MBR
2. grub 1.5 and 2 are in /boot/grub/ (on FC-3 at least)
3. both the above.


in my case, Ive got extlinux installed to MBR on /dev/sda,


If I understand your plans correctly, you want this usb drive to be able
to boot standalone.


that is the plan.

If I am correct, you want the usb drive to be bootable with no other
devices in play, and that means BIOS must be able to boot from the usb
device.  Grub has no factor in that scenario until after the device is
accessed and the boot sector is read.



cuz I got extlinux in there, it has no part at all.
except when I try to boot the laptop (using grub on /dev/hda)
and targeting /dev/sda as root.  (an interim step toward my end goal)

ie: this fails

title Nomad (Debian, kernel 2.6.8-1-386, on USB-drive)
       root    (hd1,0)
       kernel  /boot/vmlinuz-2.6.8-1-386 root=/dev/sda1 ro
       initrd  /boot/initrd.img-2.6.8-1-386
       boot

of course, this works:

title Fedora Core (2.6.9-1.724_FC3)
       root    (hd0,1)
       kernel  /boot/vmlinuz-2.6.9-1.724_FC3 ro root=LABEL=/
       initrd  /boot/initrd-2.6.9-1.724_FC3.img


Thanks for reading between the lines here..



Also, might as well answer Stuart here too.


the BIOS apparently does see the drive - sort of.
if I hit escape on the sony splash screen,
I get an ascii dialog box with 'Removable media' (or similar) as 1st choice.
But it doesnt actually boot -
it gives up instantly, and back to grub on /dev/hda


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