RFC: additional event for pm_notifier

RFC: additional event for pm_notifier

[Sebastian Ott]

hi,

on s390 certain hw features which we normally enable in our init
calls, get reset while restoring the hibernation image.
so we need a trigger to reenable them before the device callbacks
are called.

is it possible to add an additional event for the existing
pm_notifier (something like the attached patch)?

regards
sebastian


Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
---
 include/linux/notifier.h |    1 +
 kernel/power/hibernate.c |    2 ++
 2 files changed, 3 insertions(+)

Index: linux-2.6/include/linux/notifier.h
===================================================================
--- linux-2.6.orig/include/linux/notifier.h
+++ linux-2.6/include/linux/notifier.h
@@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
 #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
 #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
 #define PM_POST_RESTORE		0x0006 /* Restore failed */
+#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
+					  device callbacks */
 
 /* Console keyboard events.
  * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
Index: linux-2.6/kernel/power/hibernate.c
===================================================================
--- linux-2.6.orig/kernel/power/hibernate.c
+++ linux-2.6/kernel/power/hibernate.c
@@ -290,6 +290,8 @@ static int create_image(int platform_mod
 	if (!in_suspend)
 		platform_leave(platform_mode);
 
+	pm_notifier_call_chain(PM_RESTORE_FINISHED);
+
  Power_up:
 	sysdev_resume();
 	/* NOTE:  dpm_resume_noirq() is just a resume() for devices

Re: RFC: additional event for pm_notifier

[Rafael J. Wysocki]

On Wednesday 17 March 2010, Sebastian Ott wrote:
> hi,
> 
> on s390 certain hw features which we normally enable in our init
> calls, get reset while restoring the hibernation image.
> so we need a trigger to reenable them before the device callbacks
> are called.
> 
> is it possible to add an additional event for the existing
> pm_notifier (something like the attached patch)?
> 
> regards
> sebastian
> 
> 
> Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> ---
>  include/linux/notifier.h |    1 +
>  kernel/power/hibernate.c |    2 ++
>  2 files changed, 3 insertions(+)
> 
> Index: linux-2.6/include/linux/notifier.h
> ===================================================================
> --- linux-2.6.orig/include/linux/notifier.h
> +++ linux-2.6/include/linux/notifier.h
> @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
>  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
>  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
>  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> +					  device callbacks */
>  
>  /* Console keyboard events.
>   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> Index: linux-2.6/kernel/power/hibernate.c
> ===================================================================
> --- linux-2.6.orig/kernel/power/hibernate.c
> +++ linux-2.6/kernel/power/hibernate.c
> @@ -290,6 +290,8 @@ static int create_image(int platform_mod
>  	if (!in_suspend)
>  		platform_leave(platform_mode);
>  
> +	pm_notifier_call_chain(PM_RESTORE_FINISHED);

Hmm.  Why can't you put that in platform_leave()?

> +
>   Power_up:
>  	sysdev_resume();
>  	/* NOTE:  dpm_resume_noirq() is just a resume() for devices

Rafael

Re: RFC: additional event for pm_notifier

[Sebastian Ott]

On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:

> On Wednesday 17 March 2010, Sebastian Ott wrote:
> > hi,
> > 
> > on s390 certain hw features which we normally enable in our init
> > calls, get reset while restoring the hibernation image.
> > so we need a trigger to reenable them before the device callbacks
> > are called.
> > 
> > is it possible to add an additional event for the existing
> > pm_notifier (something like the attached patch)?
> > 
> > regards
> > sebastian
> > 
> > 
> > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > ---
> >  include/linux/notifier.h |    1 +
> >  kernel/power/hibernate.c |    2 ++
> >  2 files changed, 3 insertions(+)
> > 
> > Index: linux-2.6/include/linux/notifier.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/notifier.h
> > +++ linux-2.6/include/linux/notifier.h
> > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > +					  device callbacks */
> >  
> >  /* Console keyboard events.
> >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > Index: linux-2.6/kernel/power/hibernate.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/hibernate.c
> > +++ linux-2.6/kernel/power/hibernate.c
> > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> >  	if (!in_suspend)
> >  		platform_leave(platform_mode);
> >  
> > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> 
> Hmm.  Why can't you put that in platform_leave()?
thanks for the tip - i'll try that

> 
> > +
> >   Power_up:
> >  	sysdev_resume();
> >  	/* NOTE:  dpm_resume_noirq() is just a resume() for devices
> 
> Rafael
> 

Re: RFC: additional event for pm_notifier

[Sebastian Ott]

On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:

> On Wednesday 17 March 2010, Sebastian Ott wrote:
> > hi,
> > 
> > on s390 certain hw features which we normally enable in our init
> > calls, get reset while restoring the hibernation image.
> > so we need a trigger to reenable them before the device callbacks
> > are called.
> > 
> > is it possible to add an additional event for the existing
> > pm_notifier (something like the attached patch)?
> > 
> > regards
> > sebastian
> > 
> > 
> > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > ---
> >  include/linux/notifier.h |    1 +
> >  kernel/power/hibernate.c |    2 ++
> >  2 files changed, 3 insertions(+)
> > 
> > Index: linux-2.6/include/linux/notifier.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/notifier.h
> > +++ linux-2.6/include/linux/notifier.h
> > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > +					  device callbacks */
> >  
> >  /* Console keyboard events.
> >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > Index: linux-2.6/kernel/power/hibernate.c
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/hibernate.c
> > +++ linux-2.6/kernel/power/hibernate.c
> > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> >  	if (!in_suspend)
> >  		platform_leave(platform_mode);
> >  
> > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> 
> Hmm.  Why can't you put that in platform_leave()?

i'm confused, are you suggesting to put the actual statement in
platform_leave? this would change that all these platform_* functions
are nop's if platform_mode isn't set (i need the trigger independent
of the hibernation_mode)

or are you suggesting to implement platform_hibernation_ops for s390?
- this seems a bit too much since i only need one trigger, and again
this depends on the hibernation_mode

> 
> > +
> >   Power_up:
> >  	sysdev_resume();
> >  	/* NOTE:  dpm_resume_noirq() is just a resume() for devices
> 
> Rafael
> 

Re: RFC: additional event for pm_notifier

[Rafael J. Wysocki]

On Thursday 18 March 2010, Sebastian Ott wrote:
> 
> On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:
> 
> > On Wednesday 17 March 2010, Sebastian Ott wrote:
> > > hi,
> > > 
> > > on s390 certain hw features which we normally enable in our init
> > > calls, get reset while restoring the hibernation image.
> > > so we need a trigger to reenable them before the device callbacks
> > > are called.
> > > 
> > > is it possible to add an additional event for the existing
> > > pm_notifier (something like the attached patch)?
> > > 
> > > regards
> > > sebastian
> > > 
> > > 
> > > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > > ---
> > >  include/linux/notifier.h |    1 +
> > >  kernel/power/hibernate.c |    2 ++
> > >  2 files changed, 3 insertions(+)
> > > 
> > > Index: linux-2.6/include/linux/notifier.h
> > > ===================================================================
> > > --- linux-2.6.orig/include/linux/notifier.h
> > > +++ linux-2.6/include/linux/notifier.h
> > > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> > >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> > >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> > >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > > +					  device callbacks */
> > >  
> > >  /* Console keyboard events.
> > >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > > Index: linux-2.6/kernel/power/hibernate.c
> > > ===================================================================
> > > --- linux-2.6.orig/kernel/power/hibernate.c
> > > +++ linux-2.6/kernel/power/hibernate.c
> > > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> > >  	if (!in_suspend)
> > >  		platform_leave(platform_mode);
> > >  
> > > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> > 
> > Hmm.  Why can't you put that in platform_leave()?
> 
> i'm confused, are you suggesting to put the actual statement in
> platform_leave? this would change that all these platform_* functions
> are nop's if platform_mode isn't set (i need the trigger independent
> of the hibernation_mode)
> 
> or are you suggesting to implement platform_hibernation_ops for s390?

This one.

> - this seems a bit too much since i only need one trigger,

So you don't need to implement the other ones. :-)

You'll need to remove the check in hibernation_set_ops(), but that's fine.

[Well, it's outdated anyway, but only ACPI has been using it so far.]

> and again this depends on the hibernation_mode

That's fine as well.  If you define the ops, "platform" will be the default and
if someone wants to shoot himself in the foot by changing that, it's his
problem.

Rafael

Re: RFC: additional event for pm_notifier

[Rafael J. Wysocki]

On Thursday 18 March 2010, Rafael J. Wysocki wrote:
> On Thursday 18 March 2010, Sebastian Ott wrote:
> > 
> > On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:
> > 
> > > On Wednesday 17 March 2010, Sebastian Ott wrote:
> > > > hi,
> > > > 
> > > > on s390 certain hw features which we normally enable in our init
> > > > calls, get reset while restoring the hibernation image.
> > > > so we need a trigger to reenable them before the device callbacks
> > > > are called.
> > > > 
> > > > is it possible to add an additional event for the existing
> > > > pm_notifier (something like the attached patch)?
> > > > 
> > > > regards
> > > > sebastian
> > > > 
> > > > 
> > > > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > > > ---
> > > >  include/linux/notifier.h |    1 +
> > > >  kernel/power/hibernate.c |    2 ++
> > > >  2 files changed, 3 insertions(+)
> > > > 
> > > > Index: linux-2.6/include/linux/notifier.h
> > > > ===================================================================
> > > > --- linux-2.6.orig/include/linux/notifier.h
> > > > +++ linux-2.6/include/linux/notifier.h
> > > > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> > > >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> > > >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> > > >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > > > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > > > +					  device callbacks */
> > > >  
> > > >  /* Console keyboard events.
> > > >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > > > Index: linux-2.6/kernel/power/hibernate.c
> > > > ===================================================================
> > > > --- linux-2.6.orig/kernel/power/hibernate.c
> > > > +++ linux-2.6/kernel/power/hibernate.c
> > > > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> > > >  	if (!in_suspend)
> > > >  		platform_leave(platform_mode);
> > > >  
> > > > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> > > 
> > > Hmm.  Why can't you put that in platform_leave()?
> > 
> > i'm confused, are you suggesting to put the actual statement in
> > platform_leave? this would change that all these platform_* functions
> > are nop's if platform_mode isn't set (i need the trigger independent
> > of the hibernation_mode)
> > 
> > or are you suggesting to implement platform_hibernation_ops for s390?
> 
> This one.
> 
> > - this seems a bit too much since i only need one trigger,
> 
> So you don't need to implement the other ones. :-)
> 
> You'll need to remove the check in hibernation_set_ops(), but that's fine.

Oops, scratch that.  It's not enough.  There are a few helper functions
in kernel/power/hibernate.c that will need to be updated along with that.

Rafael

Re: RFC: additional event for pm_notifier

[Sebastian Ott]

On Thu, 18 Mar 2010, Rafael J. Wysocki wrote:

> On Thursday 18 March 2010, Rafael J. Wysocki wrote:
> > On Thursday 18 March 2010, Sebastian Ott wrote:
> > > 
> > > On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:
> > > 
> > > > On Wednesday 17 March 2010, Sebastian Ott wrote:
> > > > > hi,
> > > > > 
> > > > > on s390 certain hw features which we normally enable in our init
> > > > > calls, get reset while restoring the hibernation image.
> > > > > so we need a trigger to reenable them before the device callbacks
> > > > > are called.
> > > > > 
> > > > > is it possible to add an additional event for the existing
> > > > > pm_notifier (something like the attached patch)?
> > > > > 
> > > > > regards
> > > > > sebastian
> > > > > 
> > > > > 
> > > > > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > > > > ---
> > > > >  include/linux/notifier.h |    1 +
> > > > >  kernel/power/hibernate.c |    2 ++
> > > > >  2 files changed, 3 insertions(+)
> > > > > 
> > > > > Index: linux-2.6/include/linux/notifier.h
> > > > > ===================================================================
> > > > > --- linux-2.6.orig/include/linux/notifier.h
> > > > > +++ linux-2.6/include/linux/notifier.h
> > > > > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> > > > >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> > > > >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> > > > >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > > > > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > > > > +					  device callbacks */
> > > > >  
> > > > >  /* Console keyboard events.
> > > > >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > > > > Index: linux-2.6/kernel/power/hibernate.c
> > > > > ===================================================================
> > > > > --- linux-2.6.orig/kernel/power/hibernate.c
> > > > > +++ linux-2.6/kernel/power/hibernate.c
> > > > > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> > > > >  	if (!in_suspend)
> > > > >  		platform_leave(platform_mode);
> > > > >  
> > > > > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> > > > 
> > > > Hmm.  Why can't you put that in platform_leave()?
> > > 
> > > i'm confused, are you suggesting to put the actual statement in
> > > platform_leave? this would change that all these platform_* functions
> > > are nop's if platform_mode isn't set (i need the trigger independent
> > > of the hibernation_mode)
> > > 
> > > or are you suggesting to implement platform_hibernation_ops for s390?
> > 
> > This one.
> > 
> > > - this seems a bit too much since i only need one trigger,
> > 
> > So you don't need to implement the other ones. :-)
> > 
> > You'll need to remove the check in hibernation_set_ops(), but that's fine.
> 
> Oops, scratch that.  It's not enough.  There are a few helper functions
> in kernel/power/hibernate.c that will need to be updated along with that.
> 
> Rafael
> 

ok, thanks again. i'll try that over the weekend

sebastian

Re: RFC: additional event for pm_notifier

[Sebastian Ott]

On Thu, 18 Mar 2010, Rafael J. Wysocki wrote:

> On Thursday 18 March 2010, Sebastian Ott wrote:
> > 
> > On Wed, 17 Mar 2010, Rafael J. Wysocki wrote:
> > 
> > > On Wednesday 17 March 2010, Sebastian Ott wrote:
> > > > hi,
> > > > 
> > > > on s390 certain hw features which we normally enable in our init
> > > > calls, get reset while restoring the hibernation image.
> > > > so we need a trigger to reenable them before the device callbacks
> > > > are called.
> > > > 
> > > > is it possible to add an additional event for the existing
> > > > pm_notifier (something like the attached patch)?
> > > > 
> > > > regards
> > > > sebastian
> > > > 
> > > > 
> > > > Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
> > > > ---
> > > >  include/linux/notifier.h |    1 +
> > > >  kernel/power/hibernate.c |    2 ++
> > > >  2 files changed, 3 insertions(+)
> > > > 
> > > > Index: linux-2.6/include/linux/notifier.h
> > > > ===================================================================
> > > > --- linux-2.6.orig/include/linux/notifier.h
> > > > +++ linux-2.6/include/linux/notifier.h
> > > > @@ -250,6 +250,8 @@ static inline int notifier_to_errno(int 
> > > >  #define PM_POST_SUSPEND		0x0004 /* Suspend finished */
> > > >  #define PM_RESTORE_PREPARE	0x0005 /* Going to restore a saved image */
> > > >  #define PM_POST_RESTORE		0x0006 /* Restore failed */
> > > > +#define PM_RESTORE_FINISHED	0x0007 /* Image restored, called prior to
> > > > +					  device callbacks */
> > > >  
> > > >  /* Console keyboard events.
> > > >   * Note: KBD_KEYCODE is always sent before KBD_UNBOUND_KEYCODE, KBD_UNICODE and
> > > > Index: linux-2.6/kernel/power/hibernate.c
> > > > ===================================================================
> > > > --- linux-2.6.orig/kernel/power/hibernate.c
> > > > +++ linux-2.6/kernel/power/hibernate.c
> > > > @@ -290,6 +290,8 @@ static int create_image(int platform_mod
> > > >  	if (!in_suspend)
> > > >  		platform_leave(platform_mode);
> > > >  
> > > > +	pm_notifier_call_chain(PM_RESTORE_FINISHED);
> > > 
> > > Hmm.  Why can't you put that in platform_leave()?
> > 
> > i'm confused, are you suggesting to put the actual statement in
> > platform_leave? this would change that all these platform_* functions
> > are nop's if platform_mode isn't set (i need the trigger independent
> > of the hibernation_mode)
> > 
> > or are you suggesting to implement platform_hibernation_ops for s390?
> 
> This one.
> 
> > - this seems a bit too much since i only need one trigger,
> 
> So you don't need to implement the other ones. :-)
> 
> You'll need to remove the check in hibernation_set_ops(), but that's fine.
> 
> [Well, it's outdated anyway, but only ACPI has been using it so far.]
> 
> > and again this depends on the hibernation_mode
> 
> That's fine as well.  If you define the ops, "platform" will be the default and
> if someone wants to shoot himself in the foot by changing that, it's his
> problem.

hi,

i've got that working, but after some more thinking
i really didn't like that approach - in short, if we do that,
hibernation on s390 will allways be bound to the plattform mode
(with certain devices we will crash in our restore callbacks
if we haven't previously enabled the hw-feature, which those
devices use)

and to the your-gun-your-foot argument - if someone tests
hibernation on s390 using the reboot mode he sure cannot
expect the potential panic, depending on the involved devices

do you absolutely oppose against the idea of a new notifier event?

regards
sebastian

Re: RFC: additional event for pm_notifier

[Rafael J. Wysocki]

On Friday 26 March 2010, Sebastian Ott wrote:
>
> hi,
> 
> i've got that working, but after some more thinking
> i really didn't like that approach - in short, if we do that,
> hibernation on s390 will allways be bound to the plattform mode
> (with certain devices we will crash in our restore callbacks
> if we haven't previously enabled the hw-feature, which those
> devices use)
> 
> and to the your-gun-your-foot argument - if someone tests
> hibernation on s390 using the reboot mode he sure cannot
> expect the potential panic, depending on the involved devices

Well, on x86 using ACPI the reboot and shutdown modes only work by fortunate
conincidence, so to speak (if at all).

That said, your argument is reasonable.

> do you absolutely oppose against the idea of a new notifier event?

Yes, I do.  To the extent that I'd rather change the entire design so that the
"hibernation modes" would be platform-dependent.

Thanks,
Rafael

Re: RFC: additional event for pm_notifier

[Sebastian Ott]

On Fri, 26 Mar 2010, Rafael J. Wysocki wrote:

> On Friday 26 March 2010, Sebastian Ott wrote:
> >
> > hi,
> > 
> > i've got that working, but after some more thinking
> > i really didn't like that approach - in short, if we do that,
> > hibernation on s390 will allways be bound to the plattform mode
> > (with certain devices we will crash in our restore callbacks
> > if we haven't previously enabled the hw-feature, which those
> > devices use)
> > 
> > and to the your-gun-your-foot argument - if someone tests
> > hibernation on s390 using the reboot mode he sure cannot
> > expect the potential panic, depending on the involved devices
> 
> Well, on x86 using ACPI the reboot and shutdown modes only work by fortunate
> conincidence, so to speak (if at all).
> 
> That said, your argument is reasonable.
> 
> > do you absolutely oppose against the idea of a new notifier event?
> 
> Yes, I do.  To the extent that I'd rather change the entire design so that the
> "hibernation modes" would be platform-dependent.

ok. i implemented a hook in arch/s390

thanks
sebastian

Re: RFC: additional event for pm_notifier

[Rafael J. Wysocki]

On Wednesday 31 March 2010, Sebastian Ott wrote:
> 
> On Fri, 26 Mar 2010, Rafael J. Wysocki wrote:
> 
> > On Friday 26 March 2010, Sebastian Ott wrote:
> > >
> > > hi,
> > > 
> > > i've got that working, but after some more thinking
> > > i really didn't like that approach - in short, if we do that,
> > > hibernation on s390 will allways be bound to the plattform mode
> > > (with certain devices we will crash in our restore callbacks
> > > if we haven't previously enabled the hw-feature, which those
> > > devices use)
> > > 
> > > and to the your-gun-your-foot argument - if someone tests
> > > hibernation on s390 using the reboot mode he sure cannot
> > > expect the potential panic, depending on the involved devices
> > 
> > Well, on x86 using ACPI the reboot and shutdown modes only work by fortunate
> > conincidence, so to speak (if at all).
> > 
> > That said, your argument is reasonable.
> > 
> > > do you absolutely oppose against the idea of a new notifier event?
> > 
> > Yes, I do.  To the extent that I'd rather change the entire design so that the
> > "hibernation modes" would be platform-dependent.
> 
> ok. i implemented a hook in arch/s390

Thanks a lot.

Rafael