Grub2 on usb stick

drimades · 10-13-2012, 03:53 PM

Hi!
I installed GRUB2 on a usb stick with:

Code:

sudo grub-install --boot-directory=/mnt/lfs/boot /dev/sdb

down here you can see how is the usb mounted:

Code:

/dev/sdb1 on /mnt/lfs type ext2 (rw)

The installation process finished successfully.
Then I edited grub.cfg in /mnt/lfs/boot/grub to the following:

Code:

set default=0
set timeout=5

insmod ext2
set root=(hd1,1)

menuentry "LFS test" {
 linux /boot/vmlinuz root=/dev/sdb1 ro
}

When I restart the system booting from usb it results in a blank screen with the cursor blinking after 4-5 empty lines. Any idea why it's not showing the boot menu?

spiky0011 · 10-13-2012, 04:05 PM

Hi

What files do you have in boot

jefro · 10-13-2012, 04:09 PM

/sdb1
Shouldn't a booted device be sda?

drimades · 10-13-2012, 04:12 PM

In /mnt/lfs/boot I have grub vmlinuz vmlinuz-3.5.2
grub is a directory and the other two are same files

---------- Post added 10-13-12 at 05:13 PM ----------

Quote:

Originally Posted by jefro

/sdb1
Shouldn't a booted device be sda?

well, sda is the hdd for me

spiky0011 · 10-13-2012, 04:16 PM

Should there be other files there as well
System.map config and vmlinuz according to this
http://www.linuxfromscratch.org/lfs/...08/kernel.html

drimades · 10-13-2012, 04:34 PM

that's true, but it seems to me that the files System.map and config don't make the difference

spiky0011 · 10-13-2012, 04:39 PM

Well i,m sure the config will,
I have my usb drive grub cfg setup as

Quote:

# Begin /boot/grub/grub.cfg
set default=0
set timeout=5

insmod ext2
set root=(hd0,1)

menuentry "Planet-Spike7" {
linux /boot/vmlinuz-3.2-lfs-7.0 root=/dev/sdc1 rootdelay=5 ro

the part rootdelay=5 you might not need this gives the usb time to start up.

Mine boots from usb so reads the mbr as hd0

spiky0011 · 10-13-2012, 04:45 PM

The config file is for loading drivers and settings for your system, The kernel configuration, what makes you think you dont need it

drimades · 10-13-2012, 05:11 PM

as far as I know, it is used for preparing the image of the kernel. once you have vmlinuz (bzImage), you can keep the config file only as a reference

drimades · 10-13-2012, 05:34 PM

I've tried now to put the menuentry in the existing grub menu of the system and it starts with decompressing the kernel. it blocks with a kernel panic. in the kernel configuration I used a make allyesconfig. is it possible that it hasnt included support for the scsi devices?

spiky0011 · 10-14-2012, 01:14 AM

Hi

Can you get a grub prompt, If so try loading manually

drimades · 10-14-2012, 02:54 AM

Probably I can get to the grub shell. A question, is it syntactically correct if I add init=/bin/bash to the following:

Code:

menuentry "LFS test" {
set default=0
set timeout=5

insmod ext2
set root=(hd0,1)

 linux /boot/vmlinuz root=/dev/sdb1 rootdelay=10 init=/bin/bash ro

}

spiky0011 · 10-14-2012, 02:58 AM

With that cfg are you tryin to boot from usb

drimades · 10-14-2012, 03:07 AM

Yes, and I get VFS : Cannot open root device "sdb1" or unknown-block(0,0)

spiky0011 · 10-14-2012, 03:11 AM

Try loading manually from grub prompt, it will also let you check that everything is looking in the correct places and the correct things.

Have you tried updating grub on the host