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Subject: Re: [PATCH v5 21/31] powernv/fadump: process architected register
 state data provided by firmware
To: Michael Ellerman <mpe@ellerman.id.au>,
 linuxppc-dev <linuxppc-dev@ozlabs.org>
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From: Hari Bathini <hbathini@linux.ibm.com>
Date: Mon, 9 Sep 2019 18:53:20 +0530
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On 04/09/19 5:50 PM, Michael Ellerman wrote:
> Hari Bathini <hbathini@linux.ibm.com> writes:
>

[...]

>> +/*
>> + * CPU state data is provided by f/w. Below are the definitions
>> + * provided in HDAT spec. Refer to latest HDAT specification for
>> + * any update to this format.
>> + */
> 
> How is this meant to work? If HDAT ever changes the format they will
> break all existing kernels in the field.
> 
>> +#define HDAT_FADUMP_CPU_DATA_VERSION		1

Changes are not expected here. But this is just to cover for such scenario,
if that ever happens.

Also, I think it is a bit far-fetched to error out if versions mismatch.
Warning and proceeding sounds worthier because the changes are usually
backward compatible, if and when there are any. Will update accordingly... 

- Hari