Re: [Qemu-devel] [PATCH] Add USB sys file-system support (v2)

[Jason Wessel <jason.wessel@windriver.com>]

TJ wrote:
> On Fri, 2008-09-05 at 08:30 -0500, Jason Wessel wrote:
>   
>> I tried out the patch because it looked reasonably interesting on ubuntu
>> 7.10 64bit, and looked like a nice way to attach a local USB device, but
>> it did not quite work.
>>     
>
> What version of kvm, or what was the commit HEAD hash?
>   

Since you posed this to the qemu-devel mailing list, I tried it on the
QEMU development head.

> What does the patch report as the method of access to the USB
> file-system? 
husb: using /dev/bus/usb

> Does the same device work without the patch? 

Of course not, because the host does not have /proc/bus/usb.

The device is known to work fine if the host driver is loaded.

> The device is a
> USB-to-serial converter? Is there a host process attached to it? 
It is a pl2303 rs232 usb device.  And there is definitely no
host process or any host driver loaded.

> ( USB
> device raw access requires the host to release the device or you'll get
> all kinds of problems and potential data corruption if it is a block
> device).
>
> The location of the error you report is outside the scope of the patch
> itself. The patch is only responsible for determining the available
> devices and listing them.
>
>   
I know it is outside the patch which enables the usb searching, which is
why I asked if there are more pieces.

What might be a defect is that it did not work with the
|host:vendor_id:product_id and immediately failed.|


> The issue you're experiencing could be related to the recent changes to
> USB support introduced by Max.
>
>   
I am guessing it is unique to this class of device or perhaps even this
particular device.  When I by bypassed the failing ioctl, the device
worked to write to it (ie it echo characters), but not to read from it
(not at the usb level) but rather the rs232 level.  I assume this is
because it is selecting the wrong end points to hook up or something or
that the failed ioctl really does need to succeed. :-)

Jason.