[gentoo-user] Re: Can't find init due to inconsistent drive order

[Grant Edwards <grant.b.edwards@gmail.com>]

On 2013-07-02, Paul Hartman <paul.hartman+gentoo@gmail.com> wrote:
> On Tue, Jul 2, 2013 at 11:57 AM, Grant Edwards
><grant.b.edwards@gmail.com> wrote:

>>>>  5) For the drive with the root parition on it switch from a DOS
>>>>     parition table to a GPT partition table and use the
>>>>     root=PARTUUID=<whatever> kernel option.
>>>
>>> You don't need to switch to GPT for that.
>>
>> All the references Google can find for me say that you have to use a
>> GPT partition table if you want to specify a boot partition using
>> root=PARTUUID=<partition-uuid>.
>>
>> Does the root=PARTUUID option work for you?
>>
>> Can you point to some documentation on how you can use
>> root=PARTUID=<partition-uuid> with an DOS/MBR partition table?
>
> As Neil alluded to, you can use UUID with MBR (instead of PARTUUID and
> GPT). I have DOS/MBR partition table and my kernel commandline looks
> like:
>
> root=UUID=1d21fa55-0fa9-4d43-8d41-8b4193900efa ro log_buf_len=1M quiet
> rootfstype=ext4 raid=noautodetect
>
> (along with an initramfs)

Yes, we've already discussed that if you have an initrd (or
initramfs), and an 'init' program that handles it, you can use
filesystem labels and filesystem uuids.

The option we were discussing in the posting to which you replied is
that of using the root=PARTUUID method which is handled directly by
the kernel.  I said that requires switching from MBR to GPT, and was
told "You don't need to switch to GPT for that." The evidence for that
last statement seemed to be the fact the 'blkid' command prints out
filesystem UUIDs.

I tried using root=PARTUUID= with an MBR and the UUID values printed
by 'blkid': it didn't work.  I even modified the kernel to show the
kernel's partition UUIDs that were being compared against.

I still maintain that you _do_ need to switch to GPT to use
root=PARTUUID but would welcome any evidence or documentation that
indicates otherwise.

-- 
Grant Edwards               grant.b.edwards        Yow! The Korean War must
                                  at               have been fun.
                              gmail.com