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Subject: Re: [PATCH] ehea: Add kdump support
From: Luke Browning <lukebr@linux.vnet.ibm.com>
To: michael@ellerman.id.au
Cc: Thomas Klein <osstklei@de.ibm.com>, Michael Neuling <mikey@neuling.org>,
       Jeff Garzik <jeff@garzik.org>, Jan-Bernd Themann <themann@de.ibm.com>,
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Date: Mon, 26 Nov 2007 13:41:37 -0200
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On Mon, 2007-11-26 at 19:16 +1100, Michael Ellerman wrote:

> 
> Hi Thomas,
> 
> I'm sorry, but this patch is all wrong IMHO.
> 
> For kdump we have to assume that the kernel is fundamentally broken,
> we've panicked, so something bad has happened - every line of kernel
> code that is run decreases the chance that we'll successfully make it
> into the kdump kernel.

I agree with Michael.

> Solutions that might be better:
> 
>  a) if there are a finite number of handles and we can predict their 
>     values, just delete them all in the kdump kernel before the driver
>     loads.

This is a good solution if handles are predefined.

>  b) if there are a small & finite number of handles, save their values 
>     in a device tree property and have the kdump kernel read them and 
>     delete them before the driver loads.

Also good but is more complicated.  

>  c) if neither of those work, provide a minimal routine that _only_
>     deletes the handles in the crashed kernel.
>  d) <something else>

Can the driver or configuration method for the driver query PHYP to
determine if there are any pre-existing mappings... 

Regards, Luke

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