usb/umass, devfs: this sucks

Paul Schmehl pauls at
Wed Dec 26 15:14:34 PST 2007

--On December 26, 2007 3:45:15 PM -0700 Warren Block <wblock at> 
> Well, me too, and a USB scanner which works well.  But I understand the
> frustration.

As do I.

> Lately, I was trying to use a card reader with a too-long USB cable. Not
> only did that not work, but it could slow the system down to nothing or
> panic it.  Fixed with a powered hub...

I have encountered numerous problems with USB on Windows as well.  Some 
devices only work when plugged directly in to a port on the box.  Some are 
perfectly happy to share a hub with others.  So I don't think *all* of the 
problems are OS-related.

> It seems like we need another kind of storage, something that is known
> to be only mostly data-safe.  If the system would gracefully handle
> unexpected media removals, that would be nice.  Not everything is a
> trustworthy hard drive.
> The user ought to be able to tell the system "Yes, da0s1 is an msdos
> filesystem which I'm going to be yanking out at unexpected times.  Yes,
> I know it might lose some data, but at least figure things out and don't
> panic."

I absolutely agree with this.  At a minimum it should be possible to 
forcibly umount a device that you removed after forgetting to umount it 
first.  If I had the first clue about the code, I'd submit a patch.

Paul Schmehl (pauls at
Senior Information Security Analyst
The University of Texas at Dallas

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