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Date: Thu, 27 May 2010 22:37:51 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
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Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
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On Thu, 27 May 2010 18:25:10 +0100
Matthew Garrett <mjg59@srcf.ucam.org> wrote:

> On Thu, May 27, 2010 at 07:20:56PM +0200, Peter Zijlstra wrote:
> 
> > Suppose X (or whatever windowing system) will block all clients that try
> > to draw when you switch off your screen.
> > 
> > How would we not wake them when we do turn the screen back on and start
> > servicing the pending requests again?
> 
> How (and why) does the WoL (which may be *any* packet, not just a magic 
> one) turn the screen back on?

Well on my laptop today it works like this

A WoL packet arrives
The CPU resumes
Depp process, chipset and laptop BIOS magic happens
The kernel gets called
The kernel lets interested people know a resume occurred
The X server sees this
X reconfigures the display
X redraws the display (either by sending everyone expose events or by
keeping the bits, not sure how it works this week as it has changed over
time)

My desktop re-appears


Alan