Re: Ottawa [topics]

[Nigel Cunningham <ncunningham-3EexvZdKGZRWk0Htik3J/w@public.gmane.org>]

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Hi.

On Thu, 2005-03-17 at 15:11, Alan Stern wrote:
> On Wed, 16 Mar 2005, David Brownell wrote:
> 
> > > Wether the system IRQs must be masked or not is one thing that is
> > > platform specific during suspend. Wether devices must stop their IRQ
> > > emission, well... 
> > 
> > What's a "system IRQ" as opposed to any other kind?  Drivers don't
> > generally know or care how their IRQs are routed, they just care
> > that they get a callback.
> 
> Given that on some platforms it's necessary to leave some IRQs enabled for 
> remote wakeup to work, the definitions of FREEZE and SUSPEND need to be 
> changed.  A quiesced device does not perform DMA and does not generate 
> interrupt requests _except_ that it may issue wakeup requests (which may 
> be IRQs) if it is enabled for remote wakeup.

I don't think the definition of FREEZE needs to be changed because -
unless I misunderstand - it is only used when swsusp and Suspend2 are
doing their atomic copies. Pavel, is this right?

> I don't think this will cause any problems for Suspend To Disk.  If a 
> wakeup IRQ arrives before the system is asleep and is fielded by an 
> interrupt handler, the handler will try to start a resume.  But resume 
> needs a process context to operate, and all processes will be frozen -- so 
> nothing will happen.

Does the handler try to start a usermode helper program?

Regards,

Nigel
-- 
Nigel Cunningham
Software Engineer, Canberra, Australia
http://www.cyclades.com
Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028;  Mob: +61 (417) 100 574

Maintainer of Suspend2 Kernel Patches http://suspend2.net


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