Panic on boot with today's CURRENT, ata related

I get a kernel panic on boot with today's CURRENT on my HP Pavilion
laptop (ACPI enabled). Copied by hand:

[...]
ad0: 38154MB <IC25N040ATMR04-0> [77520/16/63] at ata0-master PIO4
ATAPI_RESET time = 70us

Fatal trap 12: page fault while in kernel mode
fault virtual address	= 0x3c
fault code		= supervisor read, page not present
instrucion pointer	= 0x8 :0xc044990e
stack pointer		= 0x10 :0xc0c21c8c
frame pointer		= 0x10 :0xc0c21cc0
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		= 0 (swapper)
[thread 0]
Stopped at ata-generic_transaction+0x80e:   testb   $0x1,0x3c(%eax)
db> trace
ata_generic_transaction(c1b25a8c,c1b25a8c,1f4,a,c1b25a8c) at
ata_generic_transaction+0x80e
ata_start(c1947c00,0,c06b906f,1,c1b25a8c) at ata_start+0x279
ata_queue_request(c1b25a8c,0,101,0,e2d9) at ata_queue_request+0x1fc
ata_controlcmd(c1947ca8,8,0,0,0) at ata_controlcmd+0x8b
ata_identify_devices(c1947c00,1,c18418b0,c0705410,c0c21d80) at
ata_identify_devices+0x162
ata_boot_attach(0,0,c0c21d80,c05181c6,0) at ata_boot_attach+0x2f
run_interrupt_driven_config_hooks(0,c1e000,c1ec00,c1e000,0) at
run_interrupt_driven_config_hooks+0x1c
mi_startup() at mi_startup+0x99
begin() at begin+0x2c

I wish there was a spell checker for things like this.

Maybe this panic is in some way related to what I've previously reported
here:
http://lists.freebsd.org/mailman/htdig/freebsd-current/2004-June/029440.html

-Radek