what is the difference between shutdown command and writing to /sys/power/state

what is the difference between shutdown command and writing to /sys/power/state

[Agarwal, Lomesh]

Does linux handles writing "disk" to /sys/power/state and shutdown -P
now differently (except writing to disk part)? I have a Xen system and
if I try both (in dom0 which is linux) then writing "disk" powers off
the system while issuing shutdown command halts the system but the
system is still power on. Dom0 is using ramdisk so writing "disk" to
/sys/power/state should essentially be same as shutdown command.

Re: what is the difference between shutdown command and writing to /sys/power/state

[Rafael J. Wysocki]

On Wednesday, 19 September 2007 20:50, Agarwal, Lomesh wrote:
> Does linux handles writing "disk" to /sys/power/state and shutdown -P
> now differently (except writing to disk part)?

Yes, it does (depending also on what you mean by 'now').

Greetings,
Rafael

RE: what is the difference between shutdown command and writing to /sys/power/state

[Agarwal, Lomesh]

Can you tell me the differences?
Also what do you mean by - depending also on what you mean by 'now'? I
gave now as a time parameter to shutdown command. How can it be
interpreted in a different way?

-----Original Message-----
From: Rafael J. Wysocki [mailto:rjw@sisk.pl] 
Sent: Wednesday, September 19, 2007 2:35 PM
To: Agarwal, Lomesh
Cc: linux-kernel@vger.kernel.org
Subject: Re: what is the difference between shutdown command and writing
to /sys/power/state

On Wednesday, 19 September 2007 20:50, Agarwal, Lomesh wrote:
> Does linux handles writing "disk" to /sys/power/state and shutdown -P
> now differently (except writing to disk part)?

Yes, it does (depending also on what you mean by 'now').

Greetings,
Rafael

Re: what is the difference between shutdown command and writing to /sys/power/state

[Rafael J. Wysocki]

On Wednesday, 19 September 2007 23:37, Agarwal, Lomesh wrote:
> Can you tell me the differences?
> Also what do you mean by - depending also on what you mean by 'now'? I

Please tell me what kernel version you're referring to.

> gave now as a time parameter to shutdown command. How can it be
> interpreted in a different way?

Sorry, I have misunderstood your post (the "now" doesn't look as a part of the
command).

Greetings,
Rafael


> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@sisk.pl] 
> Sent: Wednesday, September 19, 2007 2:35 PM
> To: Agarwal, Lomesh
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: what is the difference between shutdown command and writing
> to /sys/power/state
> 
> On Wednesday, 19 September 2007 20:50, Agarwal, Lomesh wrote:
> > Does linux handles writing "disk" to /sys/power/state and shutdown -P
> > now differently (except writing to disk part)?
> 
> Yes, it does (depending also on what you mean by 'now').

RE: what is the difference between shutdown command and writing to /sys/power/state

[Agarwal, Lomesh]

-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Rafael J.
Wysocki
Sent: Wednesday, September 19, 2007 5:09 PM
To: Agarwal, Lomesh
Cc: linux-kernel@vger.kernel.org
Subject: Re: what is the difference between shutdown command and writing
to /sys/power/state

On Wednesday, 19 September 2007 23:37, Agarwal, Lomesh wrote:
> Can you tell me the differences?
> Also what do you mean by - depending also on what you mean by 'now'? I

Please tell me what kernel version you're referring to.
[Agarwal, Lomesh] 2.6.18

RE: what is the difference between shutdown command and writing to /sys/power/state

[Agarwal, Lomesh]

Can someone tell me the flow of code for these two scenarios -
I write disk to /sys/power/state. How does system go to hibernation? How
does this trigger ACPI driver functions?
I issue shutdown command.
I am using 2.6.18 kernel.

Thanks,
Lomesh

-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Rafael J.
Wysocki
Sent: Wednesday, September 19, 2007 5:09 PM
To: Agarwal, Lomesh
Cc: linux-kernel@vger.kernel.org
Subject: Re: what is the difference between shutdown command and writing
to /sys/power/state

On Wednesday, 19 September 2007 23:37, Agarwal, Lomesh wrote:
> Can you tell me the differences?
> Also what do you mean by - depending also on what you mean by 'now'? I

Please tell me what kernel version you're referring to.

> gave now as a time parameter to shutdown command. How can it be
> interpreted in a different way?

Sorry, I have misunderstood your post (the "now" doesn't look as a part
of the
command).

Greetings,
Rafael


> -----Original Message-----
> From: Rafael J. Wysocki [mailto:rjw@sisk.pl] 
> Sent: Wednesday, September 19, 2007 2:35 PM
> To: Agarwal, Lomesh
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: what is the difference between shutdown command and
writing
> to /sys/power/state
> 
> On Wednesday, 19 September 2007 20:50, Agarwal, Lomesh wrote:
> > Does linux handles writing "disk" to /sys/power/state and shutdown
-P
> > now differently (except writing to disk part)?
> 
> Yes, it does (depending also on what you mean by 'now').
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Re: what is the difference between shutdown command and writing to /sys/power/state

[Rafael J. Wysocki]

On Thursday, 20 September 2007 20:11, Agarwal, Lomesh wrote:
> Can someone tell me the flow of code for these two scenarios -
> I write disk to /sys/power/state. How does system go to hibernation? How
> does this trigger ACPI driver functions?
> I issue shutdown command.
> I am using 2.6.18 kernel.

It's quite old for current standards. :-)

I'll need to get the source and look into it to be able to answer, so please
give me some time.

BTW, please don't top post.

Greetings,
Rafael