CELF interest in suspend-to-flash

CELF interest in suspend-to-flash

[Tim Bird]

Hi all,

Lately, the CE Linux Forum power management working group is showing some
interest in suspend-to-flash.  Is there any current work in this area?

Who should we talk to if we want to get involved with this (or lead
an effort if there isn't one)?

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================

Re: CELF interest in suspend-to-flash

[Nigel Cunningham]

Hi.

On Thu, 2004-11-11 at 04:59, Tim Bird wrote:
> Hi all,
> 
> Lately, the CE Linux Forum power management working group is showing some
> interest in suspend-to-flash.  Is there any current work in this area?
> 
> Who should we talk to if we want to get involved with this (or lead
> an effort if there isn't one)?

Can flash be treated as a swap device at the moment? If so, it might
simply be a matter of specifying the same parameter used in swapon for
the resume2= boot parameter.

If more work is required, I'd happily help, although I might be a little
slow: I'm only work on this on a voluntary basis at the moment (looking
for full time work, from next month though).

Regards,

Nigel

> =============================
> Tim Bird
> Architecture Group Chair, CE Linux Forum
> Senior Staff Engineer, Sony Electronics
> =============================
-- 
Nigel Cunningham
Pastoral Worker
Christian Reformed Church of Tuggeranong
PO Box 1004, Tuggeranong, ACT 2901

You see, at just the right time, when we were still powerless, Christ
died for the ungodly.		-- Romans 5:6

Re: CELF interest in suspend-to-flash

[Marcelo Tosatti]

On Thu, Nov 11, 2004 at 05:06:31AM +1100, Nigel Cunningham wrote:
> Hi.
> 
> On Thu, 2004-11-11 at 04:59, Tim Bird wrote:
> > Hi all,
> > 
> > Lately, the CE Linux Forum power management working group is showing some
> > interest in suspend-to-flash.  Is there any current work in this area?
> > 
> > Who should we talk to if we want to get involved with this (or lead
> > an effort if there isn't one)?
> 
> Can flash be treated as a swap device at the moment? If so, it might
> simply be a matter of specifying the same parameter used in swapon for
> the resume2= boot parameter.

Sure, you only need to have the flash as a block device (ie driven 
by the IDE code).

> If more work is required, I'd happily help, although I might be a little
> slow: I'm only work on this on a voluntary basis at the moment (looking
> for full time work, from next month though).

Re: CELF interest in suspend-to-flash

[Nigel Cunningham]

Hi.

On Thu, 2004-11-11 at 02:41, Marcelo Tosatti wrote:
> On Thu, Nov 11, 2004 at 05:06:31AM +1100, Nigel Cunningham wrote:
> > Hi.
> > 
> > On Thu, 2004-11-11 at 04:59, Tim Bird wrote:
> > > Hi all,
> > > 
> > > Lately, the CE Linux Forum power management working group is showing some
> > > interest in suspend-to-flash.  Is there any current work in this area?
> > > 
> > > Who should we talk to if we want to get involved with this (or lead
> > > an effort if there isn't one)?
> > 
> > Can flash be treated as a swap device at the moment? If so, it might
> > simply be a matter of specifying the same parameter used in swapon for
> > the resume2= boot parameter.
> 
> Sure, you only need to have the flash as a block device (ie driven 
> by the IDE code).

Cool. In that case, it should work fine with either swsusp (the mainline
implementation) or suspend2.

Regards,

Nigel
-- 
Nigel Cunningham
Pastoral Worker
Christian Reformed Church of Tuggeranong
PO Box 1004, Tuggeranong, ACT 2901

You see, at just the right time, when we were still powerless, Christ
died for the ungodly.		-- Romans 5:6

Re: CELF interest in suspend-to-flash

[Thomas Gleixner]

On Wed, 2004-11-10 at 13:41 -0200, Marcelo Tosatti wrote:
> > On Thu, 2004-11-11 at 04:59, Tim Bird wrote:
> > > Hi all,
> > > 
> > > Lately, the CE Linux Forum power management working group is showing some
> > > interest in suspend-to-flash.  Is there any current work in this area?
> > > 
> > > Who should we talk to if we want to get involved with this (or lead
> > > an effort if there isn't one)?
> > 
> > Can flash be treated as a swap device at the moment? If so, it might
> > simply be a matter of specifying the same parameter used in swapon for
> > the resume2= boot parameter.
> 
> Sure, you only need to have the flash as a block device (ie driven 
> by the IDE code).

That's true, if you are talking about Compact FLash which pretends to be
a harddisk, but I assume that the embedded people are talking about raw
FLASH chips. It's possible do this, but it will need some tweaks to the
MTD code

tglx

Re: CELF interest in suspend-to-flash

[Nigel Cunningham]

Hi.

On Thu, 2004-11-11 at 06:39, Thomas Gleixner wrote:
> On Wed, 2004-11-10 at 13:41 -0200, Marcelo Tosatti wrote:
> > > On Thu, 2004-11-11 at 04:59, Tim Bird wrote:
> > > > Hi all,
> > > > 
> > > > Lately, the CE Linux Forum power management working group is showing some
> > > > interest in suspend-to-flash.  Is there any current work in this area?
> > > > 
> > > > Who should we talk to if we want to get involved with this (or lead
> > > > an effort if there isn't one)?
> > > 
> > > Can flash be treated as a swap device at the moment? If so, it might
> > > simply be a matter of specifying the same parameter used in swapon for
> > > the resume2= boot parameter.
> > 
> > Sure, you only need to have the flash as a block device (ie driven 
> > by the IDE code).
> 
> That's true, if you are talking about Compact FLash which pretends to be
> a harddisk, but I assume that the embedded people are talking about raw
> FLASH chips. It's possible do this, but it will need some tweaks to the
> MTD code

Alternatively, a new module could be written for suspend to read/write
to it. If your idea is just tweaks, it will probably be quicker to
implement (and... I don't have access to the hardware).

Regards,

Nigel
-- 
Nigel Cunningham
Pastoral Worker
Christian Reformed Church of Tuggeranong
PO Box 1004, Tuggeranong, ACT 2901

You see, at just the right time, when we were still powerless, Christ
died for the ungodly.		-- Romans 5:6

Re: CELF interest in suspend-to-flash

[Tim Bird]

Nigel Cunningham wrote:
> Hi.
> 
> On Thu, 2004-11-11 at 06:39, Thomas Gleixner wrote:
>> On Wed, 2004-11-10 at 13:41 -0200, Marcelo Tosatti wrote:
>> > Nigel Cunningham wrote:
>> > > 
>> > > Can flash be treated as a swap device at the moment? If so, it might
>> > > simply be a matter of specifying the same parameter used in swapon for
>> > > the resume2= boot parameter.
>> > 
>> > Sure, you only need to have the flash as a block device (ie driven 
>> > by the IDE code).
>> 
>> That's true, if you are talking about Compact FLash which pretends to be
>> a harddisk, but I assume that the embedded people are talking about raw
>> FLASH chips. It's possible do this, but it will need some tweaks to the
>> MTD code

I just heard from a developer at Samsung.
They have successfully used NAND flash as a swap device using MTD.
(on a SMDK2440 platform and SMC NAND flash)
They have not tested NOR flash as swap device.  I'll try to follow up
and see if this translates into something which will work with your
suggested method.

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================

Re: CELF interest in suspend-to-flash

[Tim Bird]

Nigel Cunningham wrote:
> Can flash be treated as a swap device at the moment?
I don't know.  I'll ask around.  I'm not an expert, but we have some
people with experience with suspend-resume in our working group.

> If so, it might
> simply be a matter of specifying the same parameter used in swapon for
> the resume2= boot parameter.

Interesting... I'll pass this on and see what people think.

> If more work is required, I'd happily help, although I might be a little
> slow: I'm only work on this on a voluntary basis at the moment (looking
> for full time work, from next month though).

Also interesting. The forum moves VERY slowly on things (so you might not
hear back from me for a while), but I'll definitely keep this in mind.

Thanks very much for the response.

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================