[lfs-support] Kernel panic: VFS: unable to mount root fs - Next Diagnostic Steps?

William Harrington kb0iic at berzerkula.org
Mon May 16 06:32:16 PDT 2016


On Sun, May 15, 2016 16:36, Nathan Bibb wrote:

> The LFS system was found and showed up in my Grub Menu, but when I boot to
> that, I got the kernel panic mentioned in the subject line.
>

Hello Nathan,

Grub booted the kernel, so that part is fine. But we need more information.

The rest of the kernel panic is important. What is after "VFS: unable to
mount root fs"?

Is it unknown-block device (0,0)  or (2,0)  or something like (8,0) (8,1)
etc?

If it is 0,0... then know drives were found and the kernel didn't have a
driver or the driver didn't detect the hard drive controller and then the
block device driver didn't find a drive.

Go through your kernel config and make sure the hardware driver for your
motherboard's hard drive controller is built into the kernel and assume
that defconfig provided the right driver.

If it is something like (8,0) or (8,1) then discs were found but the
rootfs isn't right in the kernel parameter root= in grub config.

For the MMX machine, you'll need to enable the pata portion of the
sata/pata drivers section. If it is intel PIIX type, enable that (as an
example). My dual pentium 3 uses scsi, but if I needed to enable the IDE
portion I'd need the following config:

CONFIG_PATA_SERVERWORKS=y

If the machine is old enough and needs the legacy IDE support, then
CONFIG_ATA_SFF would need to be enabled, too.

If the machine has no SATA, then you won't bother looking at that portion
of the kernel configuration.

Of course make sure the following are enabled in the kernel config:
CONFIG_SCSI=y
CONFIG_BLK_DEV_SD=y


Sincerely,

William Harrington


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