[RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Zhang Rui]

Hi,

According to the ACPI spec, ACPI NVS memory region is required to
be saved/restored by OS during hibernation.

Section 15.3.2 ACPI Spec 3.0b,
"OSPM will call the _PTS control method some time before entering
a sleeping state, to allow the platform’s AML code to update
this memory image before entering the sleeping state.
After the system awakes from an S4 state, OSPM will restore this
memory area and call the _WAK control method to enable the BIOS
to reclaim its memory image."

This patch set add the mechanism to save/restore ACPI NVS memory
during hibernation.

Patch 01: call platform_begin before swsusp_shrink_memory.
	So that we can allocate enough pages for ACPI NVS memory
	before shrink the memory.

Patch 02: introduce the mechanism to save/restore ACPI NVS memory.
	
Patch 03/04: mark the ACPI NVS memory region on both
	x86_64 and x86_32 platform.

As patch 01 changes the generic code, I don't know if there are
any side effects introduced by this patch, and I'm not able to
test on other platforms.
But with Rafael's suggestion, patch 01 can be optionally dropped
because we can use the the I/O and spare pages reserved, which is
5MB at present and the NVS memory is usually tens of pages during
my test.

Any comments are welcome. :)

thanks,
rui

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Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Pavel Machek]

Hi!

> According to the ACPI spec, ACPI NVS memory region is required to
> be saved/restored by OS during hibernation.
> 
> Section 15.3.2 ACPI Spec 3.0b,
> "OSPM will call the _PTS control method some time before entering
> a sleeping state, to allow the platform???s AML code to update
> this memory image before entering the sleeping state.
> After the system awakes from an S4 state, OSPM will restore this
> memory area and call the _WAK control method to enable the BIOS
> to reclaim its memory image."
> 
> This patch set add the mechanism to save/restore ACPI NVS memory
> during hibernation.
> 
> Patch 01: call platform_begin before swsusp_shrink_memory.
> 	So that we can allocate enough pages for ACPI NVS memory
> 	before shrink the memory.

Why is it neccessary to allocate memory for a copy? We should be able
to save ACPI NVS area same way we are saving kernel pages, no?
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Rafael J. Wysocki]

On Tuesday, 8 of July 2008, Pavel Machek wrote:
> Hi!
> 
> > According to the ACPI spec, ACPI NVS memory region is required to
> > be saved/restored by OS during hibernation.
> > 
> > Section 15.3.2 ACPI Spec 3.0b,
> > "OSPM will call the _PTS control method some time before entering
> > a sleeping state, to allow the platform???s AML code to update
> > this memory image before entering the sleeping state.
> > After the system awakes from an S4 state, OSPM will restore this
> > memory area and call the _WAK control method to enable the BIOS
> > to reclaim its memory image."
> > 
> > This patch set add the mechanism to save/restore ACPI NVS memory
> > during hibernation.
> > 
> > Patch 01: call platform_begin before swsusp_shrink_memory.
> > 	So that we can allocate enough pages for ACPI NVS memory
> > 	before shrink the memory.
> 
> Why is it neccessary to allocate memory for a copy? We should be able
> to save ACPI NVS area same way we are saving kernel pages, no?

Because we want to restore it from the hibernated kernel (when it gets control
back again).

Thanks,
Rafael

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Pavel Machek]

On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> On Tuesday, 8 of July 2008, Pavel Machek wrote:
> > Hi!
> > 
> > > According to the ACPI spec, ACPI NVS memory region is required to
> > > be saved/restored by OS during hibernation.
> > > 
> > > Section 15.3.2 ACPI Spec 3.0b,
> > > "OSPM will call the _PTS control method some time before entering
> > > a sleeping state, to allow the platform???s AML code to update
> > > this memory image before entering the sleeping state.
> > > After the system awakes from an S4 state, OSPM will restore this
> > > memory area and call the _WAK control method to enable the BIOS
> > > to reclaim its memory image."
> > > 
> > > This patch set add the mechanism to save/restore ACPI NVS memory
> > > during hibernation.
> > > 
> > > Patch 01: call platform_begin before swsusp_shrink_memory.
> > > 	So that we can allocate enough pages for ACPI NVS memory
> > > 	before shrink the memory.
> > 
> > Why is it neccessary to allocate memory for a copy? We should be able
> > to save ACPI NVS area same way we are saving kernel pages, no?
> 
> Because we want to restore it from the hibernated kernel (when it gets control
> back again).

Why is that important? So we can run some ACPI methods from hibernated
kernel before restoring it?

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

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Rafael J. Wysocki]

On Friday, 11 of July 2008, Pavel Machek wrote:
> On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> > On Tuesday, 8 of July 2008, Pavel Machek wrote:
> > > Hi!
> > > 
> > > > According to the ACPI spec, ACPI NVS memory region is required to
> > > > be saved/restored by OS during hibernation.
> > > > 
> > > > Section 15.3.2 ACPI Spec 3.0b,
> > > > "OSPM will call the _PTS control method some time before entering
> > > > a sleeping state, to allow the platform???s AML code to update
> > > > this memory image before entering the sleeping state.
> > > > After the system awakes from an S4 state, OSPM will restore this
> > > > memory area and call the _WAK control method to enable the BIOS
> > > > to reclaim its memory image."
> > > > 
> > > > This patch set add the mechanism to save/restore ACPI NVS memory
> > > > during hibernation.
> > > > 
> > > > Patch 01: call platform_begin before swsusp_shrink_memory.
> > > > 	So that we can allocate enough pages for ACPI NVS memory
> > > > 	before shrink the memory.
> > > 
> > > Why is it neccessary to allocate memory for a copy? We should be able
> > > to save ACPI NVS area same way we are saving kernel pages, no?
> > 
> > Because we want to restore it from the hibernated kernel (when it gets control
> > back again).
> 
> Why is that important? So we can run some ACPI methods from hibernated
> kernel before restoring it?

We're supposed to restore it right prior to executing _WAK, which is after
we've executed _BFS.  This is a bit theoretical, because no one seems to
actaully implement _BFS, but well.

Thanks,
Rafael

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Pavel Machek]

On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote:
> On Friday, 11 of July 2008, Pavel Machek wrote:
> > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> > > On Tuesday, 8 of July 2008, Pavel Machek wrote:
> > > > Hi!
> > > > 
> > > > > According to the ACPI spec, ACPI NVS memory region is required to
> > > > > be saved/restored by OS during hibernation.
> > > > > 
> > > > > Section 15.3.2 ACPI Spec 3.0b,
> > > > > "OSPM will call the _PTS control method some time before entering
> > > > > a sleeping state, to allow the platform???s AML code to update
> > > > > this memory image before entering the sleeping state.
> > > > > After the system awakes from an S4 state, OSPM will restore this
> > > > > memory area and call the _WAK control method to enable the BIOS
> > > > > to reclaim its memory image."
> > > > > 
> > > > > This patch set add the mechanism to save/restore ACPI NVS memory
> > > > > during hibernation.
> > > > > 
> > > > > Patch 01: call platform_begin before swsusp_shrink_memory.
> > > > > 	So that we can allocate enough pages for ACPI NVS memory
> > > > > 	before shrink the memory.
> > > > 
> > > > Why is it neccessary to allocate memory for a copy? We should be able
> > > > to save ACPI NVS area same way we are saving kernel pages, no?
> > > 
> > > Because we want to restore it from the hibernated kernel (when it gets control
> > > back again).
> > 
> > Why is that important? So we can run some ACPI methods from hibernated
> > kernel before restoring it?
> 
> We're supposed to restore it right prior to executing _WAK, which is after
> we've executed _BFS.  This is a bit theoretical, because no one seems to
> actaully implement _BFS, but well.

Could we just call _BFS from the "loading" kernel, instead? That would
save us that copying code...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Rafael J. Wysocki]

On Friday, 11 of July 2008, Pavel Machek wrote:
> On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote:
> > On Friday, 11 of July 2008, Pavel Machek wrote:
> > > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> > > > On Tuesday, 8 of July 2008, Pavel Machek wrote:
> > > > > Hi!
> > > > > 
> > > > > > According to the ACPI spec, ACPI NVS memory region is required to
> > > > > > be saved/restored by OS during hibernation.
> > > > > > 
> > > > > > Section 15.3.2 ACPI Spec 3.0b,
> > > > > > "OSPM will call the _PTS control method some time before entering
> > > > > > a sleeping state, to allow the platform???s AML code to update
> > > > > > this memory image before entering the sleeping state.
> > > > > > After the system awakes from an S4 state, OSPM will restore this
> > > > > > memory area and call the _WAK control method to enable the BIOS
> > > > > > to reclaim its memory image."
> > > > > > 
> > > > > > This patch set add the mechanism to save/restore ACPI NVS memory
> > > > > > during hibernation.
> > > > > > 
> > > > > > Patch 01: call platform_begin before swsusp_shrink_memory.
> > > > > > 	So that we can allocate enough pages for ACPI NVS memory
> > > > > > 	before shrink the memory.
> > > > > 
> > > > > Why is it neccessary to allocate memory for a copy? We should be able
> > > > > to save ACPI NVS area same way we are saving kernel pages, no?
> > > > 
> > > > Because we want to restore it from the hibernated kernel (when it gets control
> > > > back again).
> > > 
> > > Why is that important? So we can run some ACPI methods from hibernated
> > > kernel before restoring it?
> > 
> > We're supposed to restore it right prior to executing _WAK, which is after
> > we've executed _BFS.  This is a bit theoretical, because no one seems to
> > actaully implement _BFS, but well.
> 
> Could we just call _BFS from the "loading" kernel, instead? That would
> save us that copying code...

I'd prefer not to, because that would require the boot kernel to support ACPI,
which need not (and in fact should not IMO) be the case at present.

Anyway, we'd have to either copy the NVS data into memory which is mapped and
can be saved, or to map the NVS area in order to save/restore it, which I
wouldn't like to do.

Thanks,
Rafael

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Yinghai Lu]

On Fri, Jul 11, 2008 at 1:59 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Friday, 11 of July 2008, Pavel Machek wrote:
>> On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote:
>> > On Friday, 11 of July 2008, Pavel Machek wrote:
>> > > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
>> > > > On Tuesday, 8 of July 2008, Pavel Machek wrote:
>> > > > > Hi!
>> > > > >
>> > > > > > According to the ACPI spec, ACPI NVS memory region is required to
>> > > > > > be saved/restored by OS during hibernation.
>> > > > > >
>> > > > > > Section 15.3.2 ACPI Spec 3.0b,
>> > > > > > "OSPM will call the _PTS control method some time before entering
>> > > > > > a sleeping state, to allow the platform???s AML code to update
>> > > > > > this memory image before entering the sleeping state.
>> > > > > > After the system awakes from an S4 state, OSPM will restore this
>> > > > > > memory area and call the _WAK control method to enable the BIOS
>> > > > > > to reclaim its memory image."
>> > > > > >
>> > > > > > This patch set add the mechanism to save/restore ACPI NVS memory
>> > > > > > during hibernation.
>> > > > > >
>> > > > > > Patch 01: call platform_begin before swsusp_shrink_memory.
>> > > > > >     So that we can allocate enough pages for ACPI NVS memory
>> > > > > >     before shrink the memory.
>> > > > >
>> > > > > Why is it neccessary to allocate memory for a copy? We should be able
>> > > > > to save ACPI NVS area same way we are saving kernel pages, no?
>> > > >
>> > > > Because we want to restore it from the hibernated kernel (when it gets control
>> > > > back again).
>> > >
>> > > Why is that important? So we can run some ACPI methods from hibernated
>> > > kernel before restoring it?
>> >
>> > We're supposed to restore it right prior to executing _WAK, which is after
>> > we've executed _BFS.  This is a bit theoretical, because no one seems to
>> > actaully implement _BFS, but well.
>>
>> Could we just call _BFS from the "loading" kernel, instead? That would
>> save us that copying code...
>
> I'd prefer not to, because that would require the boot kernel to support ACPI,
> which need not (and in fact should not IMO) be the case at present.
>
> Anyway, we'd have to either copy the NVS data into memory which is mapped and
> can be saved, or to map the NVS area in order to save/restore it, which I
> wouldn't like to do.

io_remap doesn't work at that time?

YH

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Rafael J. Wysocki]

On Friday, 11 of July 2008, Yinghai Lu wrote:
> On Fri, Jul 11, 2008 at 1:59 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > On Friday, 11 of July 2008, Pavel Machek wrote:
> >> On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote:
> >> > On Friday, 11 of July 2008, Pavel Machek wrote:
> >> > > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> >> > > > On Tuesday, 8 of July 2008, Pavel Machek wrote:
> >> > > > > Hi!
> >> > > > >
> >> > > > > > According to the ACPI spec, ACPI NVS memory region is required to
> >> > > > > > be saved/restored by OS during hibernation.
> >> > > > > >
> >> > > > > > Section 15.3.2 ACPI Spec 3.0b,
> >> > > > > > "OSPM will call the _PTS control method some time before entering
> >> > > > > > a sleeping state, to allow the platform???s AML code to update
> >> > > > > > this memory image before entering the sleeping state.
> >> > > > > > After the system awakes from an S4 state, OSPM will restore this
> >> > > > > > memory area and call the _WAK control method to enable the BIOS
> >> > > > > > to reclaim its memory image."
> >> > > > > >
> >> > > > > > This patch set add the mechanism to save/restore ACPI NVS memory
> >> > > > > > during hibernation.
> >> > > > > >
> >> > > > > > Patch 01: call platform_begin before swsusp_shrink_memory.
> >> > > > > >     So that we can allocate enough pages for ACPI NVS memory
> >> > > > > >     before shrink the memory.
> >> > > > >
> >> > > > > Why is it neccessary to allocate memory for a copy? We should be able
> >> > > > > to save ACPI NVS area same way we are saving kernel pages, no?
> >> > > >
> >> > > > Because we want to restore it from the hibernated kernel (when it gets control
> >> > > > back again).
> >> > >
> >> > > Why is that important? So we can run some ACPI methods from hibernated
> >> > > kernel before restoring it?
> >> >
> >> > We're supposed to restore it right prior to executing _WAK, which is after
> >> > we've executed _BFS.  This is a bit theoretical, because no one seems to
> >> > actaully implement _BFS, but well.
> >>
> >> Could we just call _BFS from the "loading" kernel, instead? That would
> >> save us that copying code...
> >
> > I'd prefer not to, because that would require the boot kernel to support ACPI,
> > which need not (and in fact should not IMO) be the case at present.
> >
> > Anyway, we'd have to either copy the NVS data into memory which is mapped and
> > can be saved, or to map the NVS area in order to save/restore it, which I
> > wouldn't like to do.
> 
> io_remap doesn't work at that time?

Yes, it does, but to use it, we would have to add extra information to the
image header describing the location of the NVS data within the image.
I prefer the Zhang Rui's approach to this.

Thanks,
Rafael

Re: [linux-pm] [RFC PATCH 0/4] save and restore ACPI NVS memory during hibernation

[Pavel Machek]

On Sat 2008-07-12 02:40:20, Rafael J. Wysocki wrote:
> On Friday, 11 of July 2008, Yinghai Lu wrote:
> > On Fri, Jul 11, 2008 at 1:59 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > > On Friday, 11 of July 2008, Pavel Machek wrote:
> > >> On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote:
> > >> > On Friday, 11 of July 2008, Pavel Machek wrote:
> > >> > > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote:
> > >> > > > On Tuesday, 8 of July 2008, Pavel Machek wrote:
> > >> > > > > Hi!
> > >> > > > >
> > >> > > > > > According to the ACPI spec, ACPI NVS memory region is required to
> > >> > > > > > be saved/restored by OS during hibernation.
> > >> > > > > >
> > >> > > > > > Section 15.3.2 ACPI Spec 3.0b,
> > >> > > > > > "OSPM will call the _PTS control method some time before entering
> > >> > > > > > a sleeping state, to allow the platform???s AML code to update
> > >> > > > > > this memory image before entering the sleeping state.
> > >> > > > > > After the system awakes from an S4 state, OSPM will restore this
> > >> > > > > > memory area and call the _WAK control method to enable the BIOS
> > >> > > > > > to reclaim its memory image."
> > >> > > > > >
> > >> > > > > > This patch set add the mechanism to save/restore ACPI NVS memory
> > >> > > > > > during hibernation.
> > >> > > > > >
> > >> > > > > > Patch 01: call platform_begin before swsusp_shrink_memory.
> > >> > > > > >     So that we can allocate enough pages for ACPI NVS memory
> > >> > > > > >     before shrink the memory.
> > >> > > > >
> > >> > > > > Why is it neccessary to allocate memory for a copy? We should be able
> > >> > > > > to save ACPI NVS area same way we are saving kernel pages, no?
> > >> > > >
> > >> > > > Because we want to restore it from the hibernated kernel (when it gets control
> > >> > > > back again).
> > >> > >
> > >> > > Why is that important? So we can run some ACPI methods from hibernated
> > >> > > kernel before restoring it?
> > >> >
> > >> > We're supposed to restore it right prior to executing _WAK, which is after
> > >> > we've executed _BFS.  This is a bit theoretical, because no one seems to
> > >> > actaully implement _BFS, but well.
> > >>
> > >> Could we just call _BFS from the "loading" kernel, instead? That would
> > >> save us that copying code...
> > >
> > > I'd prefer not to, because that would require the boot kernel to support ACPI,
> > > which need not (and in fact should not IMO) be the case at present.
> > >
> > > Anyway, we'd have to either copy the NVS data into memory which is mapped and
> > > can be saved, or to map the NVS area in order to save/restore it, which I
> > > wouldn't like to do.
> > 
> > io_remap doesn't work at that time?
> 
> Yes, it does, but to use it, we would have to add extra information to the
> image header describing the location of the NVS data within the image.
> I prefer the Zhang Rui's approach to this.

Ok, I guess I prefer it now, too. Feel free to add ACK on the series.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html