disk numbering

[Mark Davies <mark%ecs.vuw.ac.nz@localhost>]

I have a machine with both ahcisata and siisata that a GENERIC kernel 
finds in this order:

siisata0 at pci2 dev 0 function 0: vendor 0x1095 product 0x3132 (rev. 
0x01)
siisata0: interrupting at ioapic0 pin 18
siisata0: SiI3132, 3.0Gb/s
atabus0 at siisata0 channel 0
atabus1 at siisata0 channel 1
   [...]
ahcisata0 at pci0 dev 31 function 2: vendor 0x8086 product 0x1c02 
(rev. 0x04)
ahcisata0: interrupting at ioapic0 pin 18
ahcisata0: 64-bit DMA
ahcisata0: AHCI revision 1.30, 6 ports, 32 slots, CAP 
0xe730ff45<EMS,PSC,SSC,PMD,ISS=0x3=Gen3,SCLO,SAL,SALP,SSNTF,SNCQ,S64A>
atabus2 at ahcisata0 channel 0
atabus3 at ahcisata0 channel 1
    [...]
wd0 at atabus1 drive 0
wd0(siisata0:1:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 
(Ultra/133) (using DMA)
wd1 at atabus2 drive 0
wd1(ahcisata0:0:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 
(Ultra/133) (using DMA)
atapibus0 at atabus3: 1 targets


Whats the simplest config change to get the ahcisata attached 
buses/drives to appear first in the ordering?

cheers
mark