[blfs-support] kernel panic when booting with connected external disk

Bruce Dubbs bruce.dubbs at gmail.com
Mon Mar 18 09:06:37 PDT 2013

Michael Shell wrote:

> I strongly recommend that all data on that disk be backed
> up before any partition table changes are attempted. However,
> given that only the start value of the extended partition
> is being changed, you might be able to get by with just
> a simple change to that. Note that sda10 (sda5-10 are contained
> in sda4) is already set to begin at the correct sector 35964928
> so no changes to sda5-sda10 are even needed. I believe you
> can simply change sda4's (partition number 4, extended) starting
> sector to 35964928 via the "b" command of fdisk, available after
> enabling "expert" mode via "x". But, I've never had to do that myself.

For new drives, I've started using gdisk to create gpt partition tables. 
  That seems to solve a lot of problems.  It may be a problem for older 
system's boot drives, but otherwise it is much less complex internally 
than the 30 year old BIOS partition table structure.

> Given that none of sda4's contained logical partitions need to be
> changed, it might be a quick and totally painless fdisk tweak. The
> command gparted is a full blown repartitioning utility, but in this
> case it may not even be needed as the location of any of the actual
> filesystems are not moved at all.
> ------
> Anyway back to the problem at hand ....

>> http://dl.dropbox.com/u/8734485/Kernel_Panic

>> dmesg when external disk ( toshiba ) is NOT connected:
>> .
>> 4.232817] VFS: Mounted root (reiserfs filesystem) readonly on device 8:5.
>> dmesg additions after connecting the USB Toshiba after the login:

> That helps in knowing how the system is *supposed* to work, but the
> information we now really need is what devices are the Toshiba and
> internal drive partitions set to when the Toshiba drive is present
> during boot. And what becomes of sda5, because your error message is:
>> VFS Mount root on devices 8:5
> Something happens to 8:5 (sda5) when the Toshiba drive is seen during
> boot.
> I'd also like to see the relevant part of Ubuntu's boot with
> and without the Toshiba USB drive connected during boot so we
> can see the resultant drive ordering/naming under Ubuntu.
> Maybe we can see the same change and how Ubuntu escapes being
> bothered by it.
> I did notice that the partition name ordering is incorrect as
> sda10 has a starting sector less than sda5. This *might* have something
> to do with the problem. Also, the fact that LFS is within an extended
> partition (sda5) rather than a primary partition may also have something
> to do with the problem (What partition is Ubuntu on, primary sda1 ?).
> There is an article how to reorder the device name ordering using fdisk:

LFS on a logical partition should not be a factor.  I do always have 
/boot on /dev/sda1, but the root partition for my current set up has 
been on most partitions /dev/sda2-17, sdb1-9, or sdc1-3.  sdc is a 40G 
gpt partioned ssd with 3 partitions.

   -- Bruce

More information about the blfs-support mailing list