USB detach/attach hangs with 7.0-RELEASE and 7.1-PRERELEASE

Henrik Friedrichsen henrik at
Mon Sep 29 18:43:47 UTC 2008

On Mon, Sep 29, 2008 at 01:46:15AM +0100, Bruce M Simpson wrote:
> Hi,
> I've noticed some general instability with plugging in or removing USB 
> devices with FreeBSD 7.x, even when the devices are not actively in use.
> I had this happen with umass and ucom devices 3 times today. The machine 
> hangs solid, there are no obvious signs of a panic or trap to DDB. I 
> can't provide backtraces unfortunately -- these hangs happen on both my 
> laptop and desktop, and I usually have X running -- if I had more 
> specific information, I'd open a PR.
> Again, there seems to be no reason why this should happen, the devices 
> are off-the-shelf consumer items known to work with existing drivers, 
> and have been repeatedly used in other OSes without these hangs 
> happening; consider this an "anecdotal report".
> [For some reason my IBM laptop will often not allow me to break into DDB 
> on a driver related panic, and will just immediately reboot -- I lack 
> free time to track down exactly why this could be.
> My desktop has a USB keyboard and this appears not to be supported by 
> DDB, I ordered a PS/2 keyboard which hasn't arrived, but that's another 
> story.]
> thanks
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I can confirm those problems, however I can't provide dumps either. I remember the kernel
panicing with PAGE_FAULT errors though. Good to know, that I'm not the only one with those problems though.


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