linux-kernel - Re: Fwd: Kernel Power management ?? turning off used devices that are in use.

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Message-ID: <4EB403C0.3040803@austin.ibm.com>
Date:	Fri, 04 Nov 2011 10:24:48 -0500
From:	Joel Schopp <jschopp@...tin.ibm.com>
To:	hagar <hagar@...et.net.au>
CC:	lkml <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Srivatsa Vaddagiri <vatsa@...ibm.com>,
	Zwane Mwaikambo <zwane@....linux.org.uk>,
	Nathan Lynch <nathanl@...tin.ibm.com>,
	Ashok Raj <ashok.raj@...el.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: Fwd: Kernel Power management ?? turning off used devices that
 are in use.


> I need to be able to either switch off cpu hotpluging - or at least 
> prevent hotplugging certain cpu's
>
> there should really be a mincpu's option or better a 
> nohotplug="0,1,2,5,7,etc" option.
>
> It would appear that cpu1 is the default cpu for those interrupts - 
> and they are not being transferred to cpu0 properly.
>
The proper way to fix this is to find why the interrupts are not being 
transferred and fix that.  Forcing cpus to not be hotpluggable is just 
hiding the problem.

> I have tried the kernel parameters noapic nosmp maxcpus acpi=off 
> possible_cpus=2 etc - with no success
>
> I did find a flaw in "possible_cpus=0" - this prevents the kernel 
> booting (no cpus available )
> This option should be set to a minimum of 1
>
We allow users to shoot themselves in the foot if they do silly things.  
This is a design decision.

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