8.0-RC USB/FS problem

Stefan Esser se at freebsd.org
Wed Dec 2 19:45:55 UTC 2009

On 22.11.2009 10:47 Hans Petter Selasky wrote:
> Other operating systems do a port bus reset when the device has a problem. On 
> FreeBSD we just try a software reset via the control endpoint. I guess that it 
> is a device problem you are seeing. The USB stack in FreeBSD is faster than 
> the old one, and maybe the faster queueing of mass storage requests trigger 
> some hidden bugs in your device.
> When the problem happens try:
> sysctl hw.usb.umass.debug=-1

I have observed USB lock-ups with several external drive enclosures
that used to work with the old USB stack (and continue to work when
connected to a Windows notebook, for example). (BTW: System is AMD X2
with Nvidia chip-set and i386 kernel.)

In my case, hw.usb.debug=6 makes the drive work at some 4MB/s for
any amount of data transfered, while hw.usb.debug=5 (and an ylower
value) lets the drive pause for about 1 Minute per 100MB transfered.
I wanted to test whether short delays inserted in the places with
DPRINTFN(6, ...) make a difference, but will not get to it before
the weekend.

Regards, STefan

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