From: Matthew Dharm <mdharm-kernel@one-eyed-alien.net>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: "Rogério Brito" <rbrito@users.sf.net>,
"Alan Stern" <stern@rowland.harvard.edu>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: Question on the removable flag of USB devices
Date: Tue, 26 May 2009 10:34:32 -0700 [thread overview]
Message-ID: <20090526173432.GU28077@one-eyed-alien.net> (raw)
In-Reply-To: <4A1C1A79.2020500@s5r6.in-berlin.de>
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On Tue, May 26, 2009 at 06:36:09PM +0200, Stefan Richter wrote:
> Matthew Dharm wrote:
> > On Mon, May 25, 2009 at 01:45:54PM -0300, Rogério Brito wrote:
> >> The question is: how are devices determined to be removable or not?
> >> Sorry if this question is too naive.
> >
> > It's a bit that the device reports. The usb-storage driver passes this bit
> > to the SCSI layer.
>
> Wasn't this bit actually about removable _media_ rather than
> hotpluggable transports? (I.e. hardware where you can pull the medium
> out of the drive mechanism.) So in this sense, an USB attached HDD
> should actually not present itself as "removable" unless it's a SyQuest
> or Zip or something like that.
In fact, yes, that's the meaning of that bit. The device indicates if the
storage media may be removed from the device.
That said, a great many devices simply lie about this. Probably developers
doing a cut-and-paste from templates which have the bit set one way or the
other. The "popular" OSes don't seem to really care much about this bit...
Matt
--
Matthew Dharm Home: mdharm-usb@one-eyed-alien.net
Maintainer, Linux USB Mass Storage Driver
C: Like the Furby?
DP: He gives me the creeps. Think the SPCA will take him?
-- Cobb and Dust Puppy
User Friendly, 1/2/1999
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prev parent reply other threads:[~2009-05-26 17:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-25 16:45 Question on the removable flag of USB devices Rogério Brito
2009-05-25 18:48 ` Matthew Dharm
2009-05-26 16:36 ` Stefan Richter
2009-05-26 17:34 ` Matthew Dharm [this message]
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