Re: [RFC][PATCH] swsusp: warn about USB devices in documentation

[Pavel Machek <pavel@ucw.cz>]

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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...

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