Re: [Qemu-devel] USB port NULL pointer causes segv

[Erik Rull <erik.rull@rdsoftware.de>]

Hi Gerd,

thanks a lot.

I just had a look on usb-linux.c where the "port" could be identified.

for those that must use /proc/bus/usb it would be possible to allow the
following:
read in the "Port=" and check if it is on bus level 1, then you can
identify at least your real root hardware port - hubs won't work, but for
most users this would help at least for basic use cases.

And:
My system has the /sys/bus/usb structure, but NO udev enabled! That means
the /dev/bus/usb structure is missing! Running the existing usb-linux.c
code, I can never use USB, because /sys/... is selected but /dev/... is
used which is not checked for existance! This causes delayed problems when
you want to start using usb host devices.
I moved the /proc/bus/usb checking in front of the /sys/ checking and it
worked for me - maybe not useful for all but then the checkings for
/sys/bus/usb should be extended on the /dev/bus/usb existance check.

Additionally I have bigger problems with CD and DVD usb drives, they get
detected and routed to the guest, but the "claimend" message comes up on
the qemu monitor every 10-15 seconds and sometimes the linux usb driver
resets the port - that causes a very slow detection in the guest and I
never got it finished and I was not able to access the data on the CD. Most
USB keys work, but some also had a similar issue.

Everything tested with qemu-kvm-0.15.0

Best regards,

Erik