panic: assertion: ccb == ap->ap_err_ccb in ahci_put_err_ccb

[Francois Tigeot]

This panic occurs when trying to read a defective SATA hard drive with ahci.

On the same machine, when using the nata disk driver (by disabling ahci in
BIOS), the disk is still unreadable with READ_DMA errors but the kernel does
not panic.

System is DragonFly 2.4.1 running on a Core 2 Duo machine with an Intel ICH9
SATA chipset.

The mainboard is a Supermicro X7SBL-LN2:
http://www.supermicro.com/products/motherboard/Xeon3000/3200/X7SBL-LN2.cfm

gzipped kernel and core file are available here:
http://www.wolfpond.org/crash.dfly/

-- 
Francois Tigeot