I get a kernel "unable to handle paging request" message
when I attept to unload the usb-uhci module under 2.3.99pre8 and
pre9-1. This may have occurred in pre7, but definitely did not
occur in versions of the kernel before that. It does not occur
with the uhci module (as opposed to usb-uhci).
Some investigation revealed that the illegal memory reference
occurs in clean_descs (in usb-uhci.c). The first time that the
loop in that routine executes, the statement "q=qh->horizontal.prev;"
sets q (a pointer) to 0x5a5a5a5a (not a valid address).
Some additional data that is _probably irrelevant_, but which I include
for completeness:
One factor of the problem may be that both uhci and usb-uhci
seem to be experience either an IRQ conflict or, more likely, an
interrupt handling bug. Each of these modules when used on my
notebook computer generates five "usb_control/bulk_msg: timeout"
messages when I plug a device into the USB port, and then it disables
the port. Further investigation of that revealed that the interrupt
handler was called at least once, but did not do anything because
it determined that it was a shared interrupt that was not for the
uhci driver (oddly, /proc/interrupts after this indicates that
IRQ 10 had been received exactly 4 times, and it does not increase
thereafter, so I think it really was an interrupt for the USB).
However, I think the interrupt handling problem on my notebook
is probably separate, because I think I saw this problem on
2.3.99-pre8 (?) with usb-uhci on a desktop machine that does exhibit
the interrupt handling problem. (That same desktop machine now
crashes with a reference to memory address 0x5a5a5a77 when I tried to
load usb-uhci.o on it, but uhci.o seems to work fine.)
Adam J. Richter __ ______________ 4880 Stevens Creek Blvd, Suite 104
[EMAIL PROTECTED] \ / San Jose, California 95129-1034
+1 408 261-6630 | g g d r a s i l United States of America
fax +1 408 261-6631 "Free Software For The Rest Of Us."
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