GRUB menu not getting updated even after changing /boot/grub/grub.cfg

KNSI · 06-18-2018, 04:15 PM

Hi,

I have finished compilation of LFS-8.1 on ubuntu minimal(16.04) LTS.
during the creation of the GRUB file i had setup root to the wrong partition to.

Code:

set default=0
set timeout=5
insmod ext2
set root=(hd1)
menuentry "GNU/Linux, Linux 4.12.7-lfs-8.1" {
        linux   /boot/vmlinuz-4.12.7-lfs-8.1 root=/dev/sdb1 ro
}

hence the GRUB menu showed wrong showed:

Code:

error: no such partition

after figuring out the correct partition, i updated the grub.cfg file directly to:

Code:

set default=0
set timeout=5
insmod ext2
set root=(hd1,1)
menuentry "GNU/Linux, Linux 4.12.7-lfs-8.1" {
        linux   /boot/vmlinuz-4.12.7-lfs-8.1 root=/dev/sdb1 ro
}

but on rebooting the GRUB menu still shows the same error. i have also tried:

Code:

set default=0
set timeout=5

menuentry "GNU/Linux, Linux 4.12.7-lfs-8.1" {
        set root=(hd1,1)
        insmod ext2
        linux   /boot/vmlinuz-4.12.7-lfs-8.1 root=/dev/sda2 ro
}

as the LFS environment does not have a update-grub, im not sure how to fix this issue in the LFS environment itself for i have also erased the host system.

Head_on_a_Stick · 06-19-2018, 01:34 PM

Try

Code:

set root=(hd1,msdos1)

^ This presumes that you have a traditional msdos ("MBR" style) partition table, for a GUID partition table try

Code:

set root=(hd1,gpt1)

Or perhaps:

Code:

        linux   /boot/vmlinuz-4.12.7-lfs-8.1 root=UUID=$uuid ro

where $uuid is replaced with the actual UUID of the drive (use `/sbin/blkid` from Ubuntu to find the correct UUID).

This all presumes that your kernel configuration includes the drivers needed by your storage device

colorpurple21859 · 06-19-2018, 02:37 PM

at the grub menu hit c for grub command prompt then

Code:

set

to see where grub is looking for the grub.cfg file.

spiky0011 · 06-19-2018, 03:41 PM

Hi
It might help if you explain where all the partitions are and which grub you are using, Where is grub installed. sda or sdb.

If it is a USB drive then you might need to set a "rootdelay=10" to kernel line

X-LFS-2010 · 06-20-2018, 09:13 PM

I suggest INSURING that your editing the right grub.cfg

#1 insure the one your editing is where your installed boot loader installed it (usually /boot/grub/grub.cfg for grub2)

#2 insure grub is on the disk you think it is: it could be on sda, sda1, sdb, sdb3, or all of those

why is because where it's installed depends on which grub.cfg it will use. i make that mistake all the time!