Date: Wed, 31 May 2006 16:00:53 -0500
To: Brice Goglin <brice@myri.com>
Cc: Andrew Morton <akpm@osdl.org>, Shaohua Li <shaohua.li@intel.com>,
       linux-pci@atrey.karlin.mff.cuni.cz, linux-kernel@vger.kernel.org,
       greg@kroah.com, tom.l.nguyen@intel.com, rajesh.shah@intel.com
Subject: Re: [RFC]disable msi mode in pci_disable_device
Message-ID: <20060531210053.GE6364@austin.ibm.com>
References: <1148612307.32046.132.camel@sli10-desk.sh.intel.com> <20060526125440.0897aef5.akpm@osdl.org> <44776491.1080506@myri.com>
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From: linas@austin.ibm.com (Linas Vepstas)
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On Fri, May 26, 2006 at 10:26:57PM +0200, Brice Goglin wrote:
> Andrew Morton wrote:
> >> In
> >> his usage, pci_save_state will be called at runtime, and later (after
> >> the device operates for some time and has an error) pci_restore_state
> >> will be called.
> >
> > Is that a sane thing for a driver to be doing? (Not relevant to this issue
> > though).
> 
> The aim is to be able to recover from a memory parity error in the NIC.
> Such errors happen sometimes, especially when a cosmic ray comes by. To
> recover, we restore the state that we saved at the end of the
> initialization. As saving currently disables MSI, we currently have to
> restore the state right after saving it at the end of the initialization
> (see the end of
> myri10ge_probe in http://lkml.org/lkml/2006/5/23/24).

My experience dealing with a similar thing suggests that its usually
easier to restore the state to where it was after a cold boot, but
before the device driver touched the h/w.  

--linas

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