Re: [PATCH v5 21/31] powernv/fadump: process architected register state data provided by firmware

[Hari Bathini]

On 04/09/19 5:50 PM, Michael Ellerman wrote:
> Hari Bathini <hbath...@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