Takahiro Kambe wrote:
> In message <20071205011725.GA8335@panix.com>
> 	on Tue, 4 Dec 2007 20:17:26 -0500,
> 	Thor Lancelot Simon <tls@rek.tjls.com> wrote:
>   
>> On Wed, Dec 05, 2007 at 12:10:34AM -0000, explorer@flame.org wrote:
>>     
>>> raid0: RAID Level 1
>>> raid0: Components: /dev/wd0g /dev/wd1g
>>> raid0: Total Sectors: 566273088 (276500 MB)
>>> WARNING: double match for boot device (wd0, wd1)
>>>       
>> Two BIOS drives have the same signature because they have exactly the same
>> contents in their first sectors.  The kernel can't be certain which one you
>> actually booted from, so you might get / mounted from the other one by
>> accident.  Typically happens when one clones disks with dd instead of using
>> the tools to partition them -- the tools write a unique signature into
>> place...
>>     
> In my case, it isn't exactly the same case above:
>
> pdcsata0 at pci2 dev 2 function 0
> pdcsata0: Promise PDC20579 SATA150 controller (rev. 0x02)
> pdcsata0: interrupting at ioapic0 pin 22 (irq 10)
> pdcsata0: bus-master DMA support present
> atabus0 at pdcsata0 channel 0
> atabus1 at pdcsata0 channel 1
> ...
> pdcsata0 port 0: device present, speed: 1.5Gb/s
> pdcsata0 port 1: device present, speed: 1.5Gb/s
> wd0 at atabus0 drive 0: <Maxtor 6B250S0>
> wd0: drive supports 16-sector PIO transfers, LBA48 addressing
> wd0: 233 GB, 486344 cyl, 16 head, 63 sec, 512 bytes/sect x 490234752 sectors
> wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
> wd0(pdcsata0:0:0): using PIO mode 4, Ultra-DMA mode 6 (Ultra/133) (using DMA)
> ...
> wd1 at atabus1 drive 0: <Maxtor 6B250S0>
> wd1: drive supports 16-sector PIO transfers, LBA48 addressing
> wd1: 233 GB, 486344 cyl, 16 head, 63 sec, 512 bytes/sect x 490234752 sectors
> wd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
> wd1(pdcsata0:1:0): using PIO mode 4, Ultra-DMA mode 6 (Ultra/133) (using DMA)
> ...
> ataraid0: found 1 RAID volume
> ld0 at ataraid0 vendtype 0 unit 0: Promise ATA RAID-1 array
> ld0: 233 GB, 30515 cyl, 255 head, 63 sec, 512 bytes/sect x 490234624 sectors
> WARNING: double match for boot device (wd0, wd1)
> WARNING: double match for boot device (wd0, ld0)
>
>
> ld0 is RAID1 constructed with wd0 and wd1 by Promise controller.  So,
> first sectors of wd0 and wd1 have really the same content.
>
> After all, I configured a kernel that root device to ld0.
>
> I think we need some mechanism to specify root device's priority.
>
>   
I think you're after 'bootdev=' as a kernel parameter.

Well that's what I use.

Sarton