linux-kernel - Re: PME_Turn

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Message-ID: <20070117213318.GA2525@kroah.com>
Date:	Wed, 17 Jan 2007 13:33:18 -0800
From:	Greg KH <greg@...ah.com>
To:	"Miller, Mike (OS Dev)" <Mike.Miller@...com>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-pci@...r.kernel.org,
	"Nguyen, Tom L" <tom.l.nguyen@...el.com>,
	"Brainard, Jim" <jim.brainard@...com>,
	"Patterson, Andrew D (Linux R&D)" <andrew.patterson@...com>
Subject: Re: PME_Turn_Off in Linux

On Wed, Jan 17, 2007 at 10:43:14AM -0600, Miller, Mike (OS Dev) wrote:
> Hello,
> We've been seeing some nasty data corruption issues on some platforms.
> We've been capturing PCI-E traces looking for something nasty but we
> haven't found anything yet. One of the hardware guys if asking if there
> is a call in Linux to issue a PME_Turn_Off broadcast message.
>  
> PME_Turn_Off Broadcast Message
> Before main component power and reference clocks are turned off, the
> Root Complex or Switch Downstream Port must issue a broadcast Message
> that instructs all agents downstream of that point within the hierarchy
> to cease initiation of any subsequent PM_PME Messages, effective
> immediately upon receipt of the PME_Turn_Off Message.
> 
> This must be initiated from the root complex. Is there such a call in
> linux?

This firmware that implements the PCI-E connection should do this, I
don't think there is anything that the Operating system can do to
control this, as PCI-E should be transparant to the OS.

Unless this is on a PCI-E Hotplug system?  What is the sequence of
events that cause the data corruption?

thanks,

greg k-h
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