[Klug-general] Baffled by Kxbxnxu nxtxoxkxnx Gentoo

George Prowse george.prowse at gmail.com
Fri Feb 5 14:00:02 UTC 2010

On 05/02/2010 12:25, james morris wrote:
> On 5/2/2010, "james morris"<james at jwm-art.net>  wrote:
>> Two big problems:
>> 1) after compiling a custom kernel.
> ...
>> modules. still fails: "unable to mount root fs on unknown block (0,0)"
>>    what is "unknown block (0,0)"? i've specified grub to use (hd0,7)
>> which is the /boot partition for gentoo, and i've passed root=uuid= the
>> uuid of /.
> Just changing kernel command line back from root=uuid to root=/dev/sdb1
> means I can boot my custom kernel at last, hurray!

Yeah, unable ro mount rootfs on unknown block is just saying that the 
grub root= line is wrong, any time that happens just press "e" on the 
entry in grub and you can edit it interactively.
>> 2) seeing as i'm attempting to use the same kernel and config (except
>> 2.6.31.n where n++) as i am in debian testing, i decided to add debian
>> testing to the (gentoo installed) grub. this fails utterly to boot. i'm
>> wondering tho if that's anything to do with debian testing using grub2.
> ...
> So naturally I try changing the root kernel ocmmandline option for debian
> testing too and get "Begin: Waiting for root file system ..."
> Oh well, it's an improvement.
Well for a start it is best not to use mkinitrd. When you compile your 
kernel (make && make modules_install) there will be a bzImage in 
arch/x86/boot that is used. A bzImage is (afaik)just a bigger version of 
the old vmlinux format.

Copy over the bzImage (cp arch/x86/boot/bzImage 
/boot/kernel-2.6.XX-gentoo-rX) and amend the grub.conf. Some people only 
ever have one kernel, some people have hundreds, it all just depends on 
how you like keeping you /boot and how big it is.

Personally, I would get your system up and running with genkernel and 
then compile later kernels knowing that you always have your genkernel 
one to fall back on. Once you have done it a couple of times you can do 
it with your eyes shut, as long as you know what hardware you've got of 

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