Re: [PATCH] ehea: Add kdump support

From: Luke Browning
Date: Mon Nov 26 2007 - 10:41:35 EST


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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