Re: boot device order troubleshooting without an initrd

From: Mike Waychison
Date: Mon Apr 19 2010 - 04:43:44 EST


On 4/18/2010 4:51 PM, Arjan van de Ven wrote:
On Mon, 19 Apr 2010 00:29:54 +0200
Jan KundrÃt<jkt@xxxxxxxxxx> 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
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