From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [RFC][PATCH] swsusp: warn about USB devices in documentation Date: Mon, 20 Feb 2006 11:34:24 +0100 Message-ID: <20060220103424.GA16042@elf.ucw.cz> References: <200602192306.25170.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============27306257667901424==" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.osdl.org Errors-To: linux-pm-bounces@lists.osdl.org To: Alan Stern Cc: Linux PM List-Id: linux-pm@vger.kernel.org --===============27306257667901424== Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi! > > The appended patch contains a warning about the possiblity to lose data > > if any filesystems on USB devices are mounted before suspend. > > > > The A:-Q: part is from my correspondence with Alan Stern (thanks Alan). > > > --- linux-2.6.16-rc3-mm1.orig/Documentation/power/swsusp.txt > > +++ linux-2.6.16-rc3-mm1/Documentation/power/swsusp.txt > > @@ -17,6 +17,11 @@ Some warnings, first. > > * but it will probably only crash. > > * > > * (*) suspend/resume support is needed to make it safe. > > + * > > + * If you have any filesystems on USB devices mounted before suspend, > > + * they won't be mounted after resume and you may lose data, as though > > + * you have unplugged the USB devices with mounted filesystems on them > > + * (see the FAQ below for details). > > This isn't quite right. The filesystems _will_ still be mounted, but > inaccessible (as though you have unplugged the USB devices with mounted > filesystems on them). > > Furthermore, this may or may not happen depending on your hardware and the > type of suspend. So the "you _may_ lose data" part is good... but the > "they _won't_ be mounted" part is bad. On some types of machines (I've > heard that Apple laptops work well) the process is very reliable; so long > as the battery doesn't discharge entirely -- and provided you don't > actually unplug the device while the machine is asleep -- you can resume > safely with filesystems intact. > > Can you update the patch to fix this paragraph? Well, this is talking about suspend-to-disk... That is expected to power down machine, without providing USB bus power. If box suspends-to-disk and leaves USB up, something is wrong with the machine. Pavel -- Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted... --===============27306257667901424== Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline --===============27306257667901424==--