From owner-freebsd-current@FreeBSD.ORG  Wed Nov  5 16:03:02 2008
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Date: Wed, 05 Nov 2008 09:01:11 -0700 (MST)
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To: rink@freebsd.org
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: current@freebsd.org, bright@mu.org, hselasky@c2i.net, lme@freebsd.org,
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Subject: Re: USB4BSD release candidate number 3 - request for review
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In message: <20081105100433.GA43232@rink.nu>
            Rink Springer <rink@FreeBSD.org> writes:
: On Wed, Nov 05, 2008 at 02:18:17AM -0700, M. Warner Losh wrote:
: > In message: <200811050914.44225.hselasky@c2i.net>
: >             Hans Petter Selasky <hselasky@c2i.net> writes:
: > : On Wednesday 05 November 2008, Lars Engels wrote:
: > : > Mounting a umass device, removing it and doing an 'ls' on the mountpoint
: > : > freezes the system, I thought this should not happen with the new stack?
: > : 
: > : It is not a USB problem. It is the CAM layer that is hanging on the disk.
: > 
: > Sure it is CAM layer and not buffer cache or filesystem code?
: 
: Well, the CAM layer problem will immediately first - it does not like
: CAM busses disappearing. Once this is fixed or avoided and the problem
: still shows up, we can blame buffer cache / filesystem code.
: 
: As I suggested before, a good fix is to create one CAM bus per USB root
: hub, and use that to attach all umass devices to. This will also get rid
: of the one-bus-per-umass-device which is visually unappealling.

That might work.

It might also be useful to see if the DragonFly patches to allow this
port over or not...

Warner