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Date: Thu, 26 Aug 2010 08:59:59 +1200
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From: Andrew Thompson <thompsa@FreeBSD.org>
To: "M. Warner Losh" <imp@bsdimp.com>
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Cc: phk@phk.freebsd.dk, xcllnt@mac.com, freebsd-arch@freebsd.org
Subject: Re: RFC: root mount enhancement (round 2)
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On 26 August 2010 08:44, M. Warner Losh <imp@bsdimp.com> wrote:
> In message: <54210.1282752073@critter.freebsd.dk>
> =A0 =A0 =A0 =A0 =A0 =A0"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
> : In message <34EF2360-1B68-4E0C-8CCE-409CE141D0B8@mac.com>, Marcel Moole=
naar wri
> : tes:
> :
> : >don't want to enhance: A USB disk cannot always be used as a root
> : >file system by virtue of the USB stack releasing the root mount
> : >lock after creating the umass device, but before CAM has created
> : >the corresponding da device.
> :
> : This is a bug which is entirely unrelated to how we find the
> : root filesystem: =A0It should simply be fixed by CAM grabing a
> : root mount lock when activated from USB and releasing it
> : only when all it's stuff is done.
>
> We already do this... =A0But it is insufficient since usb discovery is
> done asynchronously...

Its more that the usb disk appears and the root mount lock is dropped
without geom tasting taken into account. This was fixed with r190677
but then I was asked to back it out (r190878).

> Scott has a similar fix in the pipeline, but I don't know the state of
> it.

It would be great to get this finished, I believe the solution Scott
wanted was to properly use intr_config_hooks to kick off usb
enumeration.


Andrew