ATA identify retries exceeded - kernel panic

[Ferruccio Zamuner]

On DFBSD 1.7.0-DEVELOPMENT #0: Sat Oct 7 00:27:36 CEST 2006,
panic on boot.
ad9: READ command timeout tag=0 serv=0 - resetting
ad9: try fallback to PIO mode
at4: resetting devices .. ata4-master: ATA identify retries exceeded
done
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x41455378
fault code            = supervisor write, page not present
instruction pointer   = 0x8:0xc019d92b
stack pointer         = 0x10:0xcfc94cdc
frame pointer         = 0x10:0xcfc94d0c
code segment          = base 0x0, limit 0xfffff, type 0x1b
                     = DPL 0, pres 1, def32 1, gran 1
processor eflags      = interrupt enabled, resume, IOPL=0
current process       = Idle
current threads       = pri 60 (CRIT)
kernel: type 12 trap, code=2
Stopped at     ad_interrupt+x038a: movl   %eax,0x148(%edx)
db> trace
ad_interrupt(cfc1e848,c1a816c0,cfc94d84,c029da35,c1d246e8) at ad_interrupt+0x38a
ata_intr(c1d246e8,0,0,0,13) at ata_intr+0x10a
ithread_handler(a,0,0,0,0) at ithread_handler+0x9d
lwkt_exit() at lwkt_exit
Bye,           \fer