root=UUID or root=LABEL not working

Dan Nicholson dbn.lists at gmail.com
Mon Feb 23 12:05:17 PST 2009


On Mon, Feb 23, 2009 at 11:43 AM, ell sam <ell.sam at e17th.com> wrote:
> Dan Nicholson wrote:
>> On Mon, Feb 23, 2009 at 11:32 AM, ell sam <ell.sam at e17th.com> wrote:
>>
>>> I am having trouble booting from the kernel on my hd to load Linux from
>>> my usb hd. I have installed everything and it works using the internal
>>> hd kernel booting from grub passing the root=/dev/sdb6 to the kernel.
>>>
>>> I want to pass something other than /dev/sdb6 so that if I plug in
>>> another drive it still boots the correct one. I have tries root=UUID=<my
>>> uuid numbers...> and root=LABEL=LFS and root=/dev/disk/by-uuid/<my
>>> uuid...> and root=/dev/disk/by-label/LFS all don't work.
>>> is there something in the kernel that needs to be configured so it
>>> works. Or maybe in initramfs etc..
>>>
>>
>> That's handled by an initramfs. Since the /dev/disk/by-*/* symlinks
>> are setup by udev, it needs to be running before the kernel tries to
>> mount the root filesystem. This can only be done in an initramfs.
>> There's no officially supported initramfs for LFS yet.
>>
>> --
>> Dan
>>
>
> that's true for root=/dev/disk/by-uuid/123.
> but the "root=UUID=123ABC" should work.

No, I'm pretty sure that's also an initramfs feature. Basically, you
check if root={UUID,LABEL}, and then poll for the symlink to be
created by udev. The kernel has no feature that I know of for doing
that. The reading of disk labels and UUIDs is done in userspace,
AFAIK.

--
Dan



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