From owner-freebsd-stable@FreeBSD.ORG  Thu Jul 19 14:49:50 2007
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To: koitsu@freebsd.org
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: LoN_Kamikaze@gmx.de, freebsd-stable@freebsd.org, idiotbg@gmail.com,
	josh@tcbug.org
Subject: Re: removing external usb hdd without unmounting causes reboot?
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In message: <20070718170559.GA11915@eos.sc1.parodius.com>
            Jeremy Chadwick <koitsu@freebsd.org> writes:
: If someone wants to work on this and needs devices/toys (thumb drives,
: external enclosures + hard disks), let me know, I will be more than
: happy to buy them the hardware needed.

Willing to fund the work on it too?  This is a volunteer project, and
you have to motivate people to work on this.  Tirades in mailing lists
has proven to be ineffective in the past.

I've looked at the issue, and generically, if a device goes away, it
is *HARD* to not panic.  The same thing happens if you eject a CF card
in a PC Card adapter in a PC Card slot.

The best one can do without massive buffer cache work is what firewire
does: it has one attachment to handle all umass devices.  When the
device goes away, it pauses all operations to that device.  If the
device comes back, it resumes the I/O .  If the device never comes
back, then the I/O never finishes.

Warner