Booting New LFS System Ends in Kernel Panic

Andrew Benton andy at
Sun Apr 3 15:47:19 PDT 2005

Dan McGhee wrote:
> Just completed an LFS 6.0 build--well Friday night.  Each time I try to 
> boot I get:
> Kernel panic:VFS:Unable to mount root fs on unknown-block (3,67)
> I know that this subject is a FAQ.  I have made sure that ext2 and ext3 
> are compiled into the kernel.  In addition, the drivers for the 
> hard drives are compiled into the kernel.
> I have Googled on this error and it seems that there are any one of over 
> a million suggestions on how to fix this--most seem inappropriate for my 
> situation.  At this point in time I don't know whether I have a GRUB or 
> kernel situation.  I can boot both Mandrake 10.1 and Windows with no 
> problem.
> The only difference between Mandrake and LFS is that Mandrake uses an 
> initrd.
I don't understand what an initrd does as I don't use one. I have no trouble booting 
without one. I think distros like to use them as it means they can boot to a certain 
point then probe for what hardware/chipset your system has, load the modules it needs 
to support that system and then continue to boot.
> Just to make sure everything was in place I ran:
> setup (hd1,2)
That will install grub on the first sector of /dev/hdb3 which won't help. If you're 
not going to install grubs menu.lst on your lfs partition (and I wouldn't, not until 
it's all working and you are using it as your main system) then just use the 
grub/menu.lst of your Mandrake host
> <VFS: Cannot open root device "hdb3" on unknown-block (3,67)
> <Please append a correct "root= " boot option
> <Kernel panic:VFS:Unable to mount root fs on unknown-block (3,67)
My guess is that the problem is in your kernel config. If I were you I'd recompile 
the kernel (again and again). When you do make menuconfig have a good look at the 
chipset options on the menu

Device Drivers  --->
ATA/ATAPI/MFM/RLL support  --->

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