USB prevents system from powering off and ucom prevents usb from being unloaded - ideas?

[Marcin Cieslak]

Michael Nottebrock wrote:
> Subject line is the executive summary of my problem:
> 
> I have a box with an Intel 945GC A2 chipset that will not poweroff on shutdown 
> if the usb kernel module is loaded (or statically compiled into the kernel). 
> Unloading the usb kernel modules sometime during shutdown (I hacked the usbd 
> rc script for this) to work around the problem helped until I needed to hook 
> up another device which uses ucom(4) to the machine. On kldunload, ucom 
> claims to detach, but remains loaded and subsequent kldunload attempts 
> trigger the error "kldunload: attempt to unload file that was loaded by the 
> kernel". The stuck ucom in turn prevents usb from getting unloaded and the 
> machine cannot poweroff.

Any other module loaded that requires ucom?

% grep MODULE_DEPEND /sys/dev/usb/*  | grep UCOM_PREFVER | grep -v -i orig
uark.c:MODULE_DEPEND(uark, ucom, UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
ubsa.c:MODULE_DEPEND(ubsa, ucom, UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
ufoma.c:MODULE_DEPEND(ufoma, ucom, UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
uftdi.c:MODULE_DEPEND(uftdi, ucom,UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
uipaq.c:MODULE_DEPEND(uipaq, ucom, UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
umct.c:MODULE_DEPEND(umct, ucom, UCOM_MINVER, UCOM_PREFVER, UCOM_MAXVER);
umodem.c:MODULE_DEPEND(umodem, ucom, UCOM_MINVER, UCOM_PREFVER,
UCOM_MAXVER);
uplcom.c:MODULE_DEPEND(uplcom, ucom, UCOM_MINVER, UCOM_PREFVER,
UCOM_MAXVER);
uvisor.c:MODULE_DEPEND(uvisor, ucom, UCOM_MINVER, UCOM_PREFVER,
UCOM_MAXVER);
uvscom.c:MODULE_DEPEND(uvscom, ucom, UCOM_MINVER, UCOM_PREFVER,
UCOM_MAXVER);

--Marcin