kernel panic with pure usb2umass pluged on pure usb1only motherboard port

[Mathieu PREVOT]

Hello Hans,

I used your code new_ihfc_1_5_5 for the kernel compilation. I obtained 
several times a kernel panic.
I have a fatal trap 12 (6 times, in the order):

Stopped at sysctl_ctx_free+0x18: pushl 0(%esi)
                                                +0x36: movl 
0x4(%eax),%eax
                      xpt_path_comp+0x19: cmpl $-0x1,0x10(%eax)
                      camisr+0xcd: movl 0x14(%eax),%eax
                                  +0xb3: movl %eax,0x28(%ecx)
                                  +0xcd: movl 0x14(%eax),%eax

with trace, I have respectively:
2 times:

sysctl_ctx_free()
device_sysctl_fini()
device_ detach()
device_delete_child()
usbd_free_device()
uhub_explore()
usb_discover()
usb_event_thread()
fork_exit()
fork_trampoline()
-- trap 0x1, eip=0, esp=0xd5424d7c, ebp=0 --

then
1time:

xpt_path_comp()
cam_periph_find()
cam_periph_alloc()
passasync()
xpt_async_bcast()
xpt_async()
probedone
camisr()
ithread_loop()
fork_exit()
fork_trampoline()
-- trap 0x1, eip=0, esp=0xd41f2d7c, ebp=0 --

and then 3 times:

camisr()
ithread_loop()
fork_exit()
fork_trampoline()
-- trap 0x1, eip=0, esp=0xd41f2d7c, ebp=0 --

is it really useful in this case to report functions ?
Maybe it can be important: the umass is also a mp3player (Zicplay).

Regards,
MP