booting with grub to /dev/sda

[Jim Cromie]

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