[PATCH] Kconfig: Update swsusp description

[PATCH] Kconfig: Update swsusp description

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rjw@sisk.pl>

Update the outdated and inaccurate description of the software suspend in
Kconfig.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/Kconfig |   39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

Index: linux-2.6.21-rc2/kernel/power/Kconfig
===================================================================
--- linux-2.6.21-rc2.orig/kernel/power/Kconfig	2007-02-28 23:54:45.000000000 +0100
+++ linux-2.6.21-rc2/kernel/power/Kconfig	2007-03-04 11:50:48.000000000 +0100
@@ -81,30 +81,35 @@ config SOFTWARE_SUSPEND
 	bool "Software Suspend"
 	depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
 	---help---
-	  Enable the possibility of suspending the machine.
-	  It doesn't need ACPI or APM.
-	  You may suspend your machine by 'swsusp' or 'shutdown -z <time>' 
-	  (patch for sysvinit needed). 
+	  Enable the suspend to disk (STD) functionality.
 
-	  It creates an image which is saved in your active swap. Upon next
+	  You can suspend your machine with 'echo disk > /sys/power/state'.
+	  Alternatively, you can use the additional userland tools available
+	  from <http://suspend.sf.net>.
+
+	  In principle it does not require ACPI or APM, although for example
+	  ACPI will be used if available.
+
+	  It creates an image which is saved in your active swap. Upon the next
 	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 	  have it detect the saved image, restore memory state from it, and
 	  continue to run as before. If you do not want the previous state to
-	  be reloaded, then use the 'noresume' kernel argument. However, note
-	  that your partitions will be fsck'd and you must re-mkswap your swap
-	  partitions. It does not work with swap files.
-
-	  Right now you may boot without resuming and then later resume but
-	  in meantime you cannot use those swap partitions/files which were
-	  involved in suspending. Also in this case there is a risk that buffers
-	  on disk won't match with saved ones.
+	  be reloaded, then use the 'noresume' kernel command line argument.
+	  Note, however, that fsck will be run on your filesystems and you will
+	  need to run mkswap against the swap partition used for the suspend.
+
+	  It also works with swap files to a limited extent (for details see
+	  <file:Documentation/power/swsusp-and-swap-files.txt>).
+
+	  Right now you may boot without resuming and resume later but in the
+	  meantime you cannot use the swap partition(s)/file(s) involved in
+	  suspending.  Also in this case you must not use the filesystems
+	  that were mounted before the suspend.  In particular, you MUST NOT
+	  MOUNT any journaled filesystems mounted before the suspend or they
+	  will get corrupted in a nasty way.
 
 	  For more information take a look at <file:Documentation/power/swsusp.txt>.
 
-	  (For now, swsusp is incompatible with PAE aka HIGHMEM_64G on i386.
-	  we need identity mapping for resume to work, and that is trivial
-	  to get with 4MB pages, but less than trivial on PAE).
-
 config PM_STD_PARTITION
 	string "Default resume partition"
 	depends on SOFTWARE_SUSPEND

Re: [PATCH] Kconfig: Update swsusp description

[Pavel Machek]

Hi!

> Index: linux-2.6.21-rc2/kernel/power/Kconfig
> ===================================================================
> --- linux-2.6.21-rc2.orig/kernel/power/Kconfig	2007-02-28 23:54:45.000000000 +0100
> +++ linux-2.6.21-rc2/kernel/power/Kconfig	2007-03-04 11:50:48.000000000 +0100
> @@ -81,30 +81,35 @@ config SOFTWARE_SUSPEND
>  	bool "Software Suspend"
>  	depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
>  	---help---
> +	  Enable the suspend to disk (STD) functionality.
>  
> +	  You can suspend your machine with 'echo disk > /sys/power/state'.
> +	  Alternatively, you can use the additional userland tools available
> +	  from <http://suspend.sf.net>.
> +
> +	  In principle it does not require ACPI or APM, although for example
> +	  ACPI will be used if available.
> +
> +	  It creates an image which is saved in your active swap. Upon the next
>  	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to

Actually, these days resume=... on kernel command line needs to be
there for suspend, too, IIRC.

> +	  Right now you may boot without resuming and resume later but in the
> +	  meantime you cannot use the swap partition(s)/file(s) involved in
> +	  suspending.  Also in this case you must not use the

I'd prefer not to encourage this use. It has too many traps ready for
people.

Otherwise looks ok.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH] Kconfig: Update swsusp description

[Rafael J. Wysocki]

On Tuesday, 6 March 2007 09:32, Pavel Machek wrote:
> Hi!
> 
> > Index: linux-2.6.21-rc2/kernel/power/Kconfig
> > ===================================================================
> > --- linux-2.6.21-rc2.orig/kernel/power/Kconfig	2007-02-28 23:54:45.000000000 +0100
> > +++ linux-2.6.21-rc2/kernel/power/Kconfig	2007-03-04 11:50:48.000000000 +0100
> > @@ -81,30 +81,35 @@ config SOFTWARE_SUSPEND
> >  	bool "Software Suspend"
> >  	depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
> >  	---help---
> > +	  Enable the suspend to disk (STD) functionality.
> >  
> > +	  You can suspend your machine with 'echo disk > /sys/power/state'.
> > +	  Alternatively, you can use the additional userland tools available
> > +	  from <http://suspend.sf.net>.
> > +
> > +	  In principle it does not require ACPI or APM, although for example
> > +	  ACPI will be used if available.
> > +
> > +	  It creates an image which is saved in your active swap. Upon the next
> >  	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
> 
> Actually, these days resume=... on kernel command line needs to be
> there for suspend, too, IIRC.

I didn't change this line, so?
 
> > +	  Right now you may boot without resuming and resume later but in the
> > +	  meantime you cannot use the swap partition(s)/file(s) involved in
> > +	  suspending.  Also in this case you must not use the
> 
> I'd prefer not to encourage this use. It has too many traps ready for
> people.

But IMHO there should be a warning that if you boot without resuming, make sure
you'll not resume after the next reboot or bad things will happen.

Greetings,
Rafael

Re: [PATCH] Kconfig: Update swsusp description

[Pavel Machek]

Hi!

> > > Index: linux-2.6.21-rc2/kernel/power/Kconfig
> > > ===================================================================
> > > --- linux-2.6.21-rc2.orig/kernel/power/Kconfig	2007-02-28 23:54:45.000000000 +0100
> > > +++ linux-2.6.21-rc2/kernel/power/Kconfig	2007-03-04 11:50:48.000000000 +0100
> > > @@ -81,30 +81,35 @@ config SOFTWARE_SUSPEND
> > >  	bool "Software Suspend"
> > >  	depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
> > >  	---help---
> > > +	  Enable the suspend to disk (STD) functionality.
> > >  
> > > +	  You can suspend your machine with 'echo disk > /sys/power/state'.
> > > +	  Alternatively, you can use the additional userland tools available
> > > +	  from <http://suspend.sf.net>.
> > > +
> > > +	  In principle it does not require ACPI or APM, although for example
> > > +	  ACPI will be used if available.
> > > +
> > > +	  It creates an image which is saved in your active swap. Upon the next
> > >  	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
> > 
> > Actually, these days resume=... on kernel command line needs to be
> > there for suspend, too, IIRC.
> 
> I didn't change this line, so?

So I should go and fix it ;-). (I'm now overloaded with email sorry
for being terse.)

Can we do something like

+	  Enable the suspend to disk (STD) functionality.
+	  In principle it does not require any support from BIOS, although 
+	  ACPI will be used if available.

+	  You can suspend your machine with 'echo disk >
+	  /sys/power/state' after placing resume=/dev/swappartition on
+	  kernel command line.
+	  Alternatively, you can use the additional userland tools available
+	  from <http://suspend.sf.net>.

(and remove ...upon next boot... section).

> > > +	  Right now you may boot without resuming and resume later but in the
> > > +	  meantime you cannot use the swap partition(s)/file(s) involved in
> > > +	  suspending.  Also in this case you must not use the
> > 
> > I'd prefer not to encourage this use. It has too many traps ready for
> > people.
> 
> But IMHO there should be a warning that if you boot without resuming, make sure
> you'll not resume after the next reboot or bad things will happen.

+	It is possible to boot without resuming and resume later but
+	if you access any partitions/files used by suspended kernel,
+	you'll probably loose your data. See ... for details.

?
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH] Kconfig: Update swsusp description

[Rafael J. Wysocki]

Hi,

On Tuesday, 6 March 2007 10:41, Pavel Machek wrote:
> Hi!
> 
> > > > Index: linux-2.6.21-rc2/kernel/power/Kconfig
> > > > ===================================================================
> > > > --- linux-2.6.21-rc2.orig/kernel/power/Kconfig	2007-02-28 23:54:45.000000000 +0100
> > > > +++ linux-2.6.21-rc2/kernel/power/Kconfig	2007-03-04 11:50:48.000000000 +0100
> > > > @@ -81,30 +81,35 @@ config SOFTWARE_SUSPEND
> > > >  	bool "Software Suspend"
> > > >  	depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
> > > >  	---help---
> > > > +	  Enable the suspend to disk (STD) functionality.
> > > >  
> > > > +	  You can suspend your machine with 'echo disk > /sys/power/state'.
> > > > +	  Alternatively, you can use the additional userland tools available
> > > > +	  from <http://suspend.sf.net>.
> > > > +
> > > > +	  In principle it does not require ACPI or APM, although for example
> > > > +	  ACPI will be used if available.
> > > > +
> > > > +	  It creates an image which is saved in your active swap. Upon the next
> > > >  	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
> > > 
> > > Actually, these days resume=... on kernel command line needs to be
> > > there for suspend, too, IIRC.
> > 
> > I didn't change this line, so?
> 
> So I should go and fix it ;-). (I'm now overloaded with email sorry
> for being terse.)
> 
> Can we do something like
> 
> +	  Enable the suspend to disk (STD) functionality.
> +	  In principle it does not require any support from BIOS, although 
> +	  ACPI will be used if available.
> 
> +	  You can suspend your machine with 'echo disk >
> +	  /sys/power/state' after placing resume=/dev/swappartition on
> +	  kernel command line.
> +	  Alternatively, you can use the additional userland tools available
> +	  from <http://suspend.sf.net>.
> 
> (and remove ...upon next boot... section).

Generally, why not, but I think Andrew has already pushed the patch to Linus,
so perhaps we can apply the changes on top of it?

> > > > +	  Right now you may boot without resuming and resume later but in the
> > > > +	  meantime you cannot use the swap partition(s)/file(s) involved in
> > > > +	  suspending.  Also in this case you must not use the
> > > 
> > > I'd prefer not to encourage this use. It has too many traps ready for
> > > people.
> > 
> > But IMHO there should be a warning that if you boot without resuming, make sure
> > you'll not resume after the next reboot or bad things will happen.
> 
> +	It is possible to boot without resuming and resume later but
> +	if you access any partitions/files used by suspended kernel,
> +	you'll probably loose your data. See ... for details.

Well, I think "access" is too weak here.  IMO we should say something like
"if you have booted without resuming and any journaled filesystems used before
the suspend have been mounted, you MUST NEVER EVER attempt to resume from the
'old' image.  In that case make sure the image is destroyed by running 'mkswap'
against the swap partition/file that contains it."

Greetings,
Rafael