Peter Billson wrote:
> Jim Kronebusch wrote:
>> On Wed, 15 Aug 2007 13:53:15 -0400 (EDT), Peter Billson wrote
>>> Hello *,
>>>    I have a problem with accessing USB drives through an un-powered USB hub.
>>>
>>>   The problem is a well known issue due to changes in the 2.6 kernel so
>>> that USB works "right." The "fix" is simply to echo a value to the
>>> proper place under /sys/bus/usb/devices when the USB drive is plugged
>>> in.
>>>
>>>   I have a simple little shell script to do the job and it works fine if
>>> run manually.
>>>
>>>   My problem is I can not seem to get the script to execute automatically
>>> on the LTSP client when a USB device is plugged in. I am sure this is
>>> just my total lack of knowledge about udev and am hoping that someone
>>> can point me to how and where to add the correct udev rule so that this
>>> magic happens.
>> This is a very basic explanation from a person with very minimal knowledge 
>> on the topic.
>>  But from what I understand the usb device sends a signal when plugged in.  
>> So you plug
>> in your USB hub and no devices are plugged in when the signal is sent thus 
>> no drives are
>> mounted.  Now when you plug a drive into the hub a signal is sent, but it 
>> stops at the
>> hub and never makes it to the client, so no drive is mounted.  If you plug 
>> the drive
>> into the hub, then plug the hub into the client, there is a drive present 
>> when the
>> signal is sent so the drive is mounted.  I think Scott Balnaeves said that 
>> you could
>> possibly probe the usb device every so often to see if a drive was present, 
>> but I can't
>> exactly remember.  If you contact him I'm sure he'll shed a great amount of 
>> light on
>> what is happening.
>>
>> Jim
> 
> Jim,
>    Thanks for the reply. I didn't get too much into the actual problem 
> since the problem itself isn't LTSP related.
> 
>    The actual "problem" is that the newer 2.6 kernels enforce the USB 
> power limits that are part of the USB specification. Older kernels did not.
> 
>    Soooo technically the older kernels (where the USB thumb drives 
> worked on unpowered hubs) where broken and the new kernels (where the 
> thumb drives don't work) are fixed.
> 
>     Much grumbling has ensued but the kernel guys are correct in their 
> implementation. After all if you just start ignoring standards and doing 
> what is convenient you would end up with M$ Vista!
> 
>    Anyway, in my case the thumb drive is seen when it is plugged into 
> the hub but the kernel chooses not to configure it based on how much 
> power it draws.
> 
>    Forcing the kernel to configure the device is trivial - my little 
> script does that - but my LTSP related problem is that I can not figure 
> out how to write a udev rule to run the script automatically on the client.
> 
>    I was hoping Scotty (the self-taught LTSP udev guru) was not too busy 
> and had some helpful advice but I am sure he is busy.

Scotty is on vacation and I think he'll return next Monday (Aug 20). if 
you don't get a response from him soon after the 20th, you might try 
emailing him directly.

Jim McQuillan
[EMAIL PROTECTED]

> 
> 
> Pete Billson
> --
> http://www.elbnet.com
> ELB Internet Service, Inc.
> Reliable Tech Support for New Jersey's Public Libraries
> 
> 
> 
> 
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