Subject: USB driver panic (usbd_alloc_xfer() ...)
To: None <>
From: None <>
List: tech-net
Date: 05/11/2005 02:34:04
I'm seeing an occasional uvm_fault/trap when 'quickly' 
pulling/re-inserting a
USB cable from/to a SuperMicro Xeon motherboard.
The USB cable is a Prolific 2302 host-to-host bridge.

The panic is in usbd_alloc_xfer(), at the line:

xfer = dev->bus->methods->allocx(dev->bus);

It appears as though 'bus' in invalid (however 'methods' generates a 
trap when dereferenced).
'bus' is a valid pointer but appears to point to an invalid usbd_bus 

The UPL driver is used as the device driver for the Prolific 2302 
bridge cable.
It is actually in the backtrace (upl_init() -> upl_tx_list_init() -> 
usbd_alloc_xfer() ).

For some reason, 'quickly' pulling/re-inserting the USB cables is 
causing the USB subsystem
to repeatedly detach/re-attach the UPL driver (& USB transport of 

Can anybody help me with this issue?


-----Original Message-----
From: Hubert Feyrer <>
To: Eric Auge <>
Sent: Wed, 11 May 2005 03:38:45 +0200 (CEST)
Subject: Re: UDP(/TCP?) bench/tuning ?

  On Tue, 10 May 2005, Eric Auge wrote:
 > I have tryed to increase :
 > Is there any other tuning params that I can tweak ?

  Sorry for not having this documented in the proper place 
(, but you may find the 
following link useful:

 - Hubert

 -- Ihr, nicht ich! ->