[SOLVED] "`/boot/grub' is not readable by GRUB on boot" & "cannot find a device for /"

Geremia · 12-27-2014, 05:00 PM

Whenever I try updating grub, I get this error:

Code:

# grub-install /dev/sda
Path `/boot/grub' is not readable by GRUB on boot. Installation is impossible. Aborting.

and

Code:

# grub-mkconfig -o /boot/grub/grub.cfg 
/usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?).

Also, I'm using the btrfs.

Richard Cranium · 12-28-2014, 01:01 AM

This thread should help.

j_v · 12-28-2014, 09:05 AM

@Richard_Cranium: url needs editing. This is what I get when I copy/paste it:

Code:

http://http//www.linuxquestions.org/questions/slackware-14/rootdev-not-found-by-sbin-init-from-initramfs-4175522403/

This seems to be the one intended?

Code:

http://www.linuxquestions.org/questions/slackware-14/rootdev-not-found-by-sbin-init-from-initramfs-4175522403/

My apologies if I'm stating the obvious.

Richard Cranium · 12-28-2014, 05:01 PM

Nope, you are correct. I've edited the post.

Geremia · 12-28-2014, 08:22 PM

Quote:

Originally Posted by Richard Cranium

This thread should help.

What specifically about that thread applies here?

I find it strange that grub could install once, but any subsequent grub-install gives the above errors.

Also, the first time I installed grub was when I was booted from the install disk, yet booting from that disk again and issuing grub-install still throws the above errors.

Also, I'm installing grub on a small (~5 MB) BIOS boot partition.

colorpurple21859 · 12-28-2014, 08:37 PM

you did mount the boot partition to /boot before running grub-install?

Geremia · 12-28-2014, 11:56 PM

Quote:

Originally Posted by colorpurple21859

you did mount the boot partition to /boot before running grub-install?

I did this: http://docs.slackware.com/howtos:sla..._first_install

colorpurple21859 · 12-29-2014, 05:10 AM

If your following that Doc make sure you have the boot partition mounted to /mnt/boot
or
boot the installation on the drive from the install disk as per the instructions at the boot screen of the install disk and once booted into your installation mount the boot partition to /boot if not mounted then rerun grub.

Richard Cranium · 12-29-2014, 08:19 AM

Quote:

Originally Posted by Geremia

What specifically about that thread applies here?

It's difficult to read your mind when you leave out details such as...

Quote:

I find it strange that grub could install once, but any subsequent grub-install gives the above errors.

Also, the first time I installed grub was when I was booted from the install disk, yet booting from that disk again and issuing grub-install still throws the above errors.

Also, I'm installing grub on a small (~5 MB) BIOS boot partition.

...so do better next time in your initial post.

Geremia · 12-30-2014, 08:51 PM

Quote:

Originally Posted by Richard Cranium

It's difficult to read your mind when you leave out details such as...
...so do better next time in your initial post.

I'm not sure what else there is to say. I was able to successfully run install-grub once, but every subsequent time running it gives the "`/boot/grub' is not readable by GRUB on boot" error. Why can I only successfully install grub once?

colorpurple21859 · 12-30-2014, 08:59 PM

so I will ask again, is the bios boot partition mounted to /boot on the root file system? The link you posted above tells how to install grub during installation. It tells me nothing about if/or where the bios boot partition is mounted. What is the ouput of

Code:

mount -l

colorpurple21859 · 12-30-2014, 09:07 PM

also the output of

Code:

fdisk -l

Geremia · 12-31-2014, 02:21 AM

Quote:

Originally Posted by colorpurple21859

What is the ouput of

Code:

mount -l

Code:

/dev/sda1 on / type btrfs (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
tmpfs on /dev/shm type tmpfs (rw)
gvfsd-fuse on /home/geremia/.gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,user=geremia)

Quote:

Originally Posted by colorpurple21859

also the output of

Code:

fdisk -l

Code:

# gdisk -l /dev/sda
GPT fdisk (gdisk) version 0.8.10

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 1953525168 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 89ABC430-B22D-4202-BD09-A19804955C61
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525134
Partitions will be aligned on 8-sector boundaries
Total free space is 0 sectors (0 bytes)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048      1953525134   931.5 GiB   8300  
   2              34            2047   1007.0 KiB  EF02

colorpurple21859 · 12-31-2014, 05:11 AM

after booting or chrooting into the slackware installation at the command prompt issue

Code:

mount /dev/sda2 /boot/efi

to mount the boot bios partition. then run grub-install or grub-mkconfig. This is assuming your booting in efi mode. If you still have errors, booting in bios mode or no /boot/efi, then mount the boot bios partition to /boot.

Code:

ls /boot

will list what is in /boot. If you just want to update the grub.cfg file then just run grub_mkconfig after mounting the boot bios partition. if After running grub-mkconfig you boot menu doesn't change, the grub.cfg file may be in the wrong location if booting in efi mode.

Geremia · 12-31-2014, 02:28 PM

Quote:

Originally Posted by colorpurple21859

assuming your booting in efi mode.

No, I'm using BIOS, not EFI.

Quote:

Originally Posted by colorpurple21859

If you still have errors, booting in bios mode or no /boot/efi, then mount the boot bios partition to /boot.

That produces an error, saying something about NTFS and how it couldn't be mounted. What filesystem type is the BIOS boot partition (of type EF02)?