> It looks like it can't access the DMA registers.
> This can be because dma_iohs[] contains the wrong values.
> Can you try the attached patch an report what it prints ?

I also added
	options  WDCDEBUG
to the config file


[ ... ]
satalink0: bus-master DMA support presentpciide_mapreg_dma: reg 0 addr 0x7ffffe42c010100
pciide_mapreg_dma: reg 1 addr 0x7ffffe42c010101
pciide_mapreg_dma: reg 2 addr 0x7ffffe42c010102
pciide_mapreg_dma: reg 3 addr 0x7ffffe42c010103
pciide_mapreg_dma: reg 4 addr 0x7ffffe42c010104
pciide_mapreg_dma: reg 5 addr 0x7ffffe42c010105
pciide_mapreg_dma: reg 6 addr 0x7ffffe42c010106
pciide_mapreg_dma: reg 7 addr 0x7ffffe42c010107
pciide_mapreg_dma: reg 0 addr 0x7ffffe42c010108
pciide_mapreg_dma: reg 1 addr 0x7ffffe42c010109
pciide_mapreg_dma: reg 2 addr 0x7ffffe42c01010a
pciide_mapreg_dma: reg 3 addr 0x7ffffe42c01010b
pciide_mapreg_dma: reg 4 addr 0x7ffffe42c01010c
pciide_mapreg_dma: reg 5 addr 0x7ffffe42c01010d
pciide_mapreg_dma: reg 6 addr 0x7ffffe42c01010e
pciide_mapreg_dma: reg 7 addr 0x7ffffe42c01010f

satalink0: primary channel wired to native-PCI mode
[ ... ]
scsibus0 at isp0: 16 targets, 8 luns per target
cmdide0 at pci0 dev 11 function 0
cmdide0: CMD Technology PCI0646 (rev. 0x01)
cmdide0: bus-master DMA support presentpciide_mapreg_dma: reg 0 addr 0x7ffffe42c012010
pciide_mapreg_dma: reg 1 addr 0x7ffffe42c012011
pciide_mapreg_dma: reg 2 addr 0x7ffffe42c012012
pciide_mapreg_dma: reg 3 addr 0x7ffffe42c012013
pciide_mapreg_dma: reg 4 addr 0x7ffffe42c012014
pciide_mapreg_dma: reg 5 addr 0x7ffffe42c012015
pciide_mapreg_dma: reg 6 addr 0x7ffffe42c012016
pciide_mapreg_dma: reg 7 addr 0x7ffffe42c012017
pciide_mapreg_dma: reg 0 addr 0x7ffffe42c012018
pciide_mapreg_dma: reg 1 addr 0x7ffffe42c012019
pciide_mapreg_dma: reg 2 addr 0x7ffffe42c01201a
pciide_mapreg_dma: reg 3 addr 0x7ffffe42c01201b
pciide_mapreg_dma: reg 4 addr 0x7ffffe42c01201c
pciide_mapreg_dma: reg 5 addr 0x7ffffe42c01201d
pciide_mapreg_dma: reg 6 addr 0x7ffffe42c01201e
pciide_mapreg_dma: reg 7 addr 0x7ffffe42c01201f

cmdide0: primary channel wired to compatibility mode
cmdide0: primary channel interrupting at isa irq 14
atabus2 at cmdide0 channel 0
cmdide0: secondary channel wired to compatibility mode
cmdide0: secondary channel interrupting at isa irq 15
atabus3 at cmdide0 channel 1
isa0 at sio0
[ ... ]
wd0 at atabus1 drive 0scsibus0: waiting 2 seconds for devices to settle...
pciide_irqack: reg 0x7ffffe42c01010a
: <ST3250823AS>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 232 GB, 484521 cyl, 16 head, 63 sec, 512 bytes/sect x 488397168 sectors
pciide_irqack: reg 0x7ffffe42c012012

unexpected machine check:

    mces    = 0x1
    vector  = 0x670
    param   = 0xfffffc0000006068
    pc      = 0xfffffc00004fddf4
    ra      = 0xfffffc00004e98f4
    code    = 0x98
    curlwp = 0xfffffc0000ade780
        pid = 9.1, comm = atabus2

panic: machine check
Stopped in pid 9.1 (atabus2) at netbsd:cpu_Debugger+0x4:        ret     zero,(ra
)
db> bt
cpu_Debugger() at netbsd:cpu_Debugger+0x4
panic() at netbsd:panic+0x1e8
machine_check() at netbsd:machine_check+0x234
interrupt() at netbsd:interrupt+0x1e8
XentInt() at netbsd:XentInt+0x1c
--- interrupt (from ipl 4) ---
cia_swiz_io_read_1() at netbsd:cia_swiz_io_read_1+0x14
pciide_irqack() at netbsd:pciide_irqack+0x54
cmd646_9_irqack() at netbsd:cmd646_9_irqack+0xb8
wdcprobe1() at netbsd:wdcprobe1+0xc5c
wdc_drvprobe() at netbsd:wdc_drvprobe+0x44
atabusconfig() at netbsd:atabusconfig+0x78
atabus_thread() at netbsd:atabus_thread+0x7c
exception_return() at netbsd:exception_return
--- root of call graph ---
db> reboot
syncing disks... pciide_irqack: reg 0x7ffffe42c01010a
done
rebooting...

==================================

(gdb) list *(0xfffffc00004fddf4)
0xfffffc00004fddf4 is in cia_swiz_io_read_1 (pci_swiz_bus_io_chipdep.c:673).
668             tmpioh = ioh + off;
669             offset = tmpioh & 3;
670             port = (u_int32_t *)((tmpioh << CHIP_ADDR_SHIFT) |
671                 (0 << CHIP_SIZE_SHIFT));
672             val = *port;
673             rval = ((val) >> (8 * offset)) & 0xff;
674
675             return rval;
676     }
677
(gdb)