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Old 07-25-2008, 10:03 AM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Hello. I'm having a problem with a self-compiled kernel. I can't use
UUID to specify my root partition; however, using "root=/dev/sda8"
works. When I try to boot using the UUID, I get this:

> VFS: Cannot open root device "xxxxx" or unknown-block(0,0)

That's somewhat annoying as you can imagine. I triple-checked to be sure
that my kernel contains everything needed to boot. Here is the boot
stanza that fails (with the UUID value removed):

> title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> root (hd0,7)
> kernel /boot/vmlinuz-2.6.26-beamer1 root=UUID=[...] ro quiet
splash
> quiet

However, this boot stanza succeeds:

> title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> root (hd0,7)
> kernel /boot/vmlinuz-2.6.26-beamer1 root=/dev/sda8 ro
> boot

It's the UUID that's failing, but I can't find where I can enable UUID's
in my kernel. Note that I'm not using an initrd--everything should be
compiled into the kernel.

Here is my config file:

http://home.earthlink.net/~mumia.w.18.spam/docs/uuid.config.txt

I'm using the kernel from kernel.org compiled for i386. I'm so close;
please help me get UUIDs working the way they should.



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Old 07-25-2008, 02:10 PM
Rashkae
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Mumia W. wrote:
> Hello. I'm having a problem with a self-compiled kernel. I can't use
> UUID to specify my root partition; however, using "root=/dev/sda8"
> works. When I try to boot using the UUID, I get this:
>
> > VFS: Cannot open root device "xxxxx" or unknown-block(0,0)
>
> That's somewhat annoying as you can imagine. I triple-checked to be sure
> that my kernel contains everything needed to boot. Here is the boot
> stanza that fails (with the UUID value removed):
>
> > title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> > root (hd0,7)
> > kernel /boot/vmlinuz-2.6.26-beamer1 root=UUID=[...] ro quiet
> splash
> > quiet
>
> However, this boot stanza succeeds:
>
> > title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> > root (hd0,7)
> > kernel /boot/vmlinuz-2.6.26-beamer1 root=/dev/sda8 ro
> > boot
>
> It's the UUID that's failing, but I can't find where I can enable UUID's
> in my kernel. Note that I'm not using an initrd--everything should be
> compiled into the kernel.
>
> Here is my config file:
>
> http://home.earthlink.net/~mumia.w.18.spam/docs/uuid.config.txt
>
> I'm using the kernel from kernel.org compiled for i386. I'm so close;
> please help me get UUIDs working the way they should.
>
>
>

My research on the subject (via google) has revealed a shocking and sad
truth. The kernel built in file system detection cannot use UUIDs. The
only way for this to work as intended is to use initrd/initramfs.



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Old 07-25-2008, 02:22 PM
"Jason Crain"
 
Default Cannot use UUID with self-compiled kernel (Hardy)

On Fri, July 25, 2008 5:03 am, Mumia W. wrote:
> Hello. I'm having a problem with a self-compiled kernel. I can't use
> UUID to specify my root partition; however, using "root=/dev/sda8"
> works. When I try to boot using the UUID, I get this:
>
> > VFS: Cannot open root device "xxxxx" or unknown-block(0,0)
>
> That's somewhat annoying as you can imagine. I triple-checked to be sure
> that my kernel contains everything needed to boot. Here is the boot
> stanza that fails (with the UUID value removed):
>
> > title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> > root (hd0,7)
> > kernel /boot/vmlinuz-2.6.26-beamer1 root=UUID=[...] ro quiet
> splash
> > quiet
>
> However, this boot stanza succeeds:
>
> > title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> > root (hd0,7)
> > kernel /boot/vmlinuz-2.6.26-beamer1 root=/dev/sda8 ro
> > boot
>
> It's the UUID that's failing, but I can't find where I can enable UUID's
> in my kernel. Note that I'm not using an initrd--everything should be
> compiled into the kernel.
>

When you run without an initrd, you have to have static /dev entries,
correct? Or at least enough /dev entries to get the root filesystm
mounted. The /dev/disk/by-uuid entries are created by udev, and I can't
think of a sensible way they could be created statically. I suggest
either enable initrd or stick with root=/dev/sda8.

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Old 07-25-2008, 02:26 PM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Rashkae wrote:
> Mumia W. wrote:
>> Hello. I'm having a problem with a self-compiled kernel. I can't use
>> UUID to specify my root partition; however, using "root=/dev/sda8"
>> works. When I try to boot using the UUID, I get this:
>>
>> > VFS: Cannot open root device "xxxxx" or unknown-block(0,0)
>> [...]
>
> My research on the subject (via google) has revealed a shocking and sad
> truth. The kernel built in file system detection cannot use UUIDs. The
> only way for this to work as intended is to use initrd/initramfs.
>
>
>

:-O

Thanks Rashkae. Can you give me the links? Are there any bugs filed?



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Old 07-25-2008, 02:57 PM
Rashkae
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Mumia W. wrote:
> Rashkae wrote:
>> Mumia W. wrote:
>>> Hello. I'm having a problem with a self-compiled kernel. I can't use
>>> UUID to specify my root partition; however, using "root=/dev/sda8"
>>> works. When I try to boot using the UUID, I get this:
>>>
>>> > VFS: Cannot open root device "xxxxx" or unknown-block(0,0)
>>> [...]
>> My research on the subject (via google) has revealed a shocking and sad
>> truth. The kernel built in file system detection cannot use UUIDs. The
>> only way for this to work as intended is to use initrd/initramfs.
>>
>>
>>
>
> :-O
>
> Thanks Rashkae. Can you give me the links? Are there any bugs filed?
>
>
>

It's not a bug.. Being able to specify a root device by UUID is just one
of the many benefits initramfs offers.

http://newsgroups.derkeiler.com/Archive/Uk/uk.comp.os.linux/2007-03/msg00069.html

I think the direction of kernel devs is to offload as much stuff to
userspace as possible, so I doubt anyone will be interested in
integrating the UUID stuff into the kernel.

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Old 07-25-2008, 03:19 PM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Jason Crain wrote:
> On Fri, July 25, 2008 5:03 am, Mumia W. wrote:
>> [...]
>> It's the UUID that's failing, but I can't find where I can enable UUID's
>> in my kernel. Note that I'm not using an initrd--everything should be
>> compiled into the kernel.
>>
>
> When you run without an initrd, you have to have static /dev entries,
> correct? Or at least enough /dev entries to get the root filesystm
> mounted. The /dev/disk/by-uuid entries are created by udev, and I can't
> think of a sensible way they could be created statically. I suggest
> either enable initrd or stick with root=/dev/sda8.
>

I'm beginning to see, thanks.



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Old 07-25-2008, 04:14 PM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Rashkae wrote:
>
> It's not a bug.. Being able to specify a root device by UUID is just one
> of the many benefits initramfs offers.
>
> http://newsgroups.derkeiler.com/Archive/Uk/uk.comp.os.linux/2007-03/msg00069.html
>
> I think the direction of kernel devs is to offload as much stuff to
> userspace as possible, so I doubt anyone will be interested in
> integrating the UUID stuff into the kernel.
>

Thank you. I filed a bug anyway:
http://bugzilla.kernel.org/show_bug.cgi?id=11162




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Old 07-25-2008, 06:36 PM
Derek Broughton
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Mumia W. wrote:

> Rashkae wrote:
>>
>> It's not a bug.. Being able to specify a root device by UUID is just one
>> of the many benefits initramfs offers.
>>
>>
http://newsgroups.derkeiler.com/Archive/Uk/uk.comp.os.linux/2007-03/msg00069.html
>>
>> I think the direction of kernel devs is to offload as much stuff to
>> userspace as possible, so I doubt anyone will be interested in
>> integrating the UUID stuff into the kernel.
>>
>
> Thank you. I filed a bug anyway:
> http://bugzilla.kernel.org/show_bug.cgi?id=11162

Certainly there's no chance of getting this behaviour changed _without_
filing bugs. The worst that can happen is that it'll be closed as "Wont
fix".

Why though do you not want an initrd?
--
derek


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Old 07-25-2008, 09:16 PM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Derek Broughton wrote:
> [...]
> Why though do you not want an initrd?

Every time I attempted to create one in the past, it failed miserably.



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Old 07-25-2008, 11:22 PM
"Mumia W."
 
Default Cannot use UUID with self-compiled kernel (Hardy)

Rashkae wrote:
>
> It's not a bug.. Being able to specify a root device by UUID is just one
> of the many benefits initramfs offers.
> [...]

Thanks for the information about the initramfs/initrd. I've managed to
get it to work by "cheating." I used the initrd from kernel 2.6.24:

> title Ubuntu 8.04.1, kernel 2.6.26-beamer1
> root (hd0,7)
> kernel /boot/vmlinuz-2.6.26-beamer1 root=UUID=[...] ro
> initrd /boot/initrd.img-2.6.24-19-generic
> boot

I get a very quick message during bootup saying that it failed to make
modules.dep, but so far the machine hasn't crashed hard ;-)




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