Re: grub error if first kernel not found.

[Michael Evans]

This is something I've never had to work with before, but the SD reader
is probably a USB device.  The BIOS will provide an emulation layer for
the USB device as the 0th disk if booting from it; however it probably
won't provide any support for it at all for it when booted from the
hard drive.  Thus grub on the hard drive probably can't even find files
on the flash drive.

A way of testing that would be to place a canary file on the flash
drive, then trying to find it the next time the hard drive grub loads. 
I recall it being escape, c (or even just c) to get the grub shell. 
Once you have that you want to run this:

find /canary_file

To see if it's even possible to use a setup like you desire.

An alternative may be to try booting from the flash drive first, then the hard drive, if the bios will hold that configuration.

Another alternative might be to investigate a small pre-boot
environment that will operate within an environment that does
reccognize external systems.  The problem there is that it'd most
probably already be linux, though in 'single user' mode.  From there
you'd want to chainload something else, only I don't recall any project
that would do that, and nothing showed up on a quick google search.

Another possibility would be creating a freedos floppy image that
somehow had USB support, and using it to either somehow chain in to
windows (maybe workable?) or loadlin a linux kernel from a loaded
filesystem.

However the most likely, and easiest, thing to do would probably be to
use the BIOS methods mentioned above.  If it remembers and can boot
from the device across insert/removals to have the SD card as a higher
priority and boot off it if inserted; or if it can't to have clearly
written instructions for the user to press F12 or whatever at a
specific time to get a specific result (a list of bootable devices) and
select the proper device.

On Fri, Jul 31, 2009 at 3:45 AM, Vikas Ghavate <address@hidden> wrote:

Hi,

Hope everyone is well today. I have Windows XP installed on HD and Ubuntu installed on SD card. I have installed grub on 1st partition on HD.
I want the PC to load grub and boot Ubuntu from SD card, if the SD card is in, or-else boot from windows on HD.

Let me explain the situation:
I want to use a PC on windows XP, but if there is any problem with XP then i will call the client ask him to push in the SD card and reboot the PC. Once PC starts booting it will load grub and grub will then find the SD card and will boot ubuntu kernel, and i can login and diagnose XP from ubuntu. Once this is done i can ask client to push out the SD card and switch on the computer. Now computer will not find ubuntu on SD card so it will load XP.

Could you please assist me in this problem?

Regards,

Vikas Ghavate
Software Engineer
(0044) 07946043331

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