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

Pierre M.R. prousselet at sfr.fr
Wed Mar 20 05:04:23 PDT 2013

Pierre M.R. wrote:
> Dr.-Ing. Edgar Alwers wrote:
>> On Monday 18 March 2013 00:37:25 Michael Shell wrote:
>>> Anyway, before you do anything, what we want to see what name the
>>> Toshiba and sda partitions are given when the Toshiba drive is
>>> already connected during boot.
>>> However, there is a big problem with getting that crucial information
>>> isn't there? Namely, that you can't just get it from a dmesg because
>>> the system will fail to boot.
>> We partially solve this problem taking pictures of the boot messages: we put a
>> rootdelay= 50.
>> Kernel-1.jpg shows the boot process before the delay, Kernel-2.jpg shows the
>> process after delay, until panic. ( LFS partition, external disk connected )
>> You may find also the partition tables for sda and for the external disk sdb
>> as well as the dmesg results in the included files
>> Regards,
>> Edgar
>> http://dl.dropbox.com/u/8734485/Kernel_Panic_2/dmesg-sda-sdb-18032013
>> http://dl.dropbox.com/u/8734485/Kernel_Panic_2/Gparted-sda.png
>> http://dl.dropbox.com/u/8734485/Kernel_Panic_2/Gparted-sdb.png
>> http://dl.dropbox.com/u/8734485/Kernel_Panic_2/Kernel-1.JPG
>> http://dl.dropbox.com/u/8734485/Kernel_Panic_2/Kernel-2.JPG
> Kernel-1.JPG shows sda-1to8 and sdb-1to11. I would conclude that, in
> this case, the laptop boots from the external HD.
> Pierre
A workaround is to compile an LFS kernel with usb system as *modules* so 
that the kernel can't know about the external HD before mounting root fs 
and loading the usb modules.


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