Re: boot device order troubleshooting without an initrd

[Mike Waychison <mikew@google.com>]

On 4/18/2010 4:51 PM, Arjan van de Ven wrote:
> On Mon, 19 Apr 2010 00:29:54 +0200
> Jan Kundrát<jkt@gentoo.org>  wrote:
>
>> Hi folks,
>> I'm looking for a way to pass a correct "root" parameter to the kernel
>> from the bootloader, independently on the number of attached disks. My
>> machine (VIA EPIA SN-1800) has four SATA ports and one CF card slot.
>> The CF slot is visible as an IDE device. The BIOS is configured for
>> booting from the CF card, and Grub2 has absolutely no problems
>> booting the kernel.
>>
>> The problem I'm facing is that if there are no SATA disks attached, my
>> CF card gets called /dev/sda, while if I attach two SATA drives, the
>> CF card gets called /dev/sdc. I can solve that "in userspace" without
>
>
> so the problem is that the boot order you want is pretty much opposite
> from what "normal" people want.
> AHCI sata before CF slots is pretty much the right thing and what most
> people will use.... most people will have their OS on AHCI SATA, and
> occasionally stick in some photo card or whatever.... and they'd ask
> the flipside question basically.
>
>
> We could have pretty evil things in the kernel, so that we'd deal with
> multiple root= lines in the kernel, one by one trying them until one
> sticks. Right now we don't.... but if you make a clean enough patch
> it might even pass the review here...
>

Multiple root devices here may help..  I recently added support for 
enumerating multiple root devices to kinit in klibc to work around some 
configuration issues on our servers.

http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=5b5b6f5192af5c3fa30fe605e8842c62421adbd4