From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Vegard Nossum <vegard.nossum@gmail.com>,
Matthew Wilcox <matthew@wil.cx>,
Pekka J Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org, dsd@gentoo.org,
mdharm-usb@one-eyed-alien.net, linux-usb@vger.kernel.org,
vegardno@ifi.uio.no, James.Bottomley@hansenpartnership.com,
linux-scsi@vger.kernel.org, Greg KH <greg@kroah.com>
Subject: Re: [RFC/PATCH] usb-storage: wait for device scanning before mounting root
Date: Fri, 20 Jun 2008 18:37:56 +0200 [thread overview]
Message-ID: <485BDCE4.2010303@s5r6.in-berlin.de> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0806201130390.2719-100000@iolanthe.rowland.org>
Alan Stern wrote:
> New USB devices can appear at any time. None are present when the
> system is started; they are all detected dynamically by the khubd
> thread.
>
> While I'm not familiar with the details of any other hotpluggable
> buses (like Firewire), I imagine much the same is true for them.
It's very similar with FireWire. FireWire devices announce SBP-2 target
capability (if they have it) after they became ready. The ieee1394 or
firewire core then scans or re-scans them in a process context. Then
upper layer drivers like the SBP-2 driver are matched, bound, probed.
If SBP-2 targets went through a power state change, they typically first
power everything up (spin up media etc.) before they announce their
protocol capabilities, and this may of course take a while. Before that
they just are inaccessible, and it is unknown whether they could become
candidates for access by upper layer drivers.
--
Stefan Richter
-=====-==--- -==- =-=--
http://arcgraph.de/sr/
prev parent reply other threads:[~2008-06-20 16:40 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-24 20:21 Pekka J Enberg
2008-04-24 21:08 ` Alan Stern
2008-04-24 21:25 ` Pekka J Enberg
2008-04-24 22:56 ` Greg KH
2008-04-24 23:30 ` Matthew Dharm
2008-04-25 6:30 ` Pekka J Enberg
2008-04-25 7:04 ` Matthew Dharm
2008-04-25 8:19 ` Pekka J Enberg
2008-04-25 15:35 ` Matthew Dharm
2008-04-25 16:05 ` Greg KH
2008-04-25 6:09 ` Pekka J Enberg
2008-04-25 7:53 ` Stefan Richter
2008-04-25 8:15 ` Pekka J Enberg
2008-04-25 9:11 ` Matthew Wilcox
2008-06-19 18:23 ` Matthew Wilcox
2008-06-19 18:39 ` Stefan Richter
2008-06-19 18:43 ` Stefan Richter
2008-06-19 18:54 ` Matthew Wilcox
2008-06-19 19:52 ` Matthew Dharm
2008-06-19 20:49 ` Matthew Wilcox
2008-06-19 21:19 ` Stefan Richter
2008-06-19 19:54 ` Stefan Richter
2008-06-19 20:22 ` Matthew Wilcox
2008-06-19 20:34 ` Stefan Richter
2008-06-19 21:39 ` Alan Stern
2008-06-19 23:13 ` David Brownell
2008-06-20 9:53 ` Gabor Gombas
2008-06-20 14:14 ` Matthew Dharm
2008-06-20 15:15 ` Vegard Nossum
2008-06-20 15:31 ` Matthew Wilcox
2008-06-20 15:42 ` Alan Stern
2008-06-20 16:37 ` Stefan Richter [this message]
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