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Date: Wed, 17 Jan 2007 13:33:18 -0800
From: Greg KH <greg@kroah.com>
To: "Miller, Mike (OS Dev)" <Mike.Miller@hp.com>
Cc: LKML <linux-kernel@vger.kernel.org>, linux-pci@vger.kernel.org,
       "Nguyen, Tom L" <tom.l.nguyen@intel.com>,
       "Brainard, Jim" <jim.brainard@hp.com>,
       "Patterson, Andrew D (Linux R&D)" <andrew.patterson@hp.com>
Subject: Re: PME_Turn_Off in Linux
Message-ID: <20070117213318.GA2525@kroah.com>
References: <E717642AF17E744CA95C070CA815AE550116B7C8@cceexc23.americas.cpqcorp.net>
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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