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Re: Unable top boot newly installed machine



In <4A781792.8050009@cox.net>, Ron Johnson wrote:
>On 2009-08-04 02:47, Alex Samad wrote:
>> On Mon, Aug 03, 2009 at 09:20:29PM -0500, Ron Johnson wrote:
>>> On 2009-08-03 16:04, Alex Samad wrote:
>>>> Hi
>>>>
>>>> I have just installed a machine from a daily build deb installer, I
>>>> did the whole disk encryption chioce and now when it is finished and
>>>> tries to reboot I can't find the root fs :(
>>>>
>>>> any ideas ?
>>> Grub config file misconfigured?
>> I think not, because grub hands over to the initiramfs scripts and its
>> local-top that is waiting - but this is an assumption on my part.
>There are two layers to this cake:

3 or 4 actually.

1. Your BIOS, which has to locate the GRUB MBR on a disk.  This is 
controlled by your BIOS "boot order" settings.

2. The GRUB MBR, which has to locate /boot/menu.lst or whatever GRUB 2.x 
uses.

3. The GRUB loader, which uses the root (hd0,0) to determine where to load 
your kernel and (optional) initrd from into memory.

--> You know everything above here works. <--

4. The initrd/kernel which reads the root= option on the kernel command-line 
(passed to it by GRUB) to determine what device contains the / file system.

>If grub points to the *wrong* partition (on, possibly, the wrong
>disk), then the "can't find the root fs" message appears.

"waiting for root fs..."
then
"can't find root fs"

Is usually one of two things:
1. Your root= option on the kernel command-line is wrong, that device never 
appears so the kernel can't find /sbin/init or the initrd can't switch/pivot 
root.  Check your menu.lst.

2. Your kernel/initrd is missing a module that is required to make the / 
file system or the block device it is on active.  Most distributions', 
including Lenny's, scripts that make initrds are fairly good at this, but 
few things are perfect.  You should be able to get a shell inside the initrd 
and attempt to load modules etc. to get the real / file system up.  You'll 
probably discover what module is missing at that point.  A bug might be in 
order.

It might also be because:
3. The initrd fails to bring up the device containing the / file system 
because the way it starts the various crypto, RAID, LVM, EVMS, etc. layers 
doesn't result in your block device being created.  If you can get a prompt 
inside the initrd, issue a few commands, then exit the shell and let the 
initrd continue with the boot process because it can now find your device, 
you have this problem; a bug might be in order.
-- 
Boyd Stephen Smith Jr.           	 ,= ,-_-. =.
bss@iguanasuicide.net            	((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy 	 `-'(. .)`-'
http://iguanasuicide.net/        	     \_/

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