Re: [PATCH v4 1/7] powerpc/fadump: Move the metadata region to start of the reserved area.

[Mahesh Jagannath Salgaonkar <mahesh@linux.vnet.ibm.com>]

On 04/22/2018 07:28 AM, Nicholas Piggin wrote:
> On Fri, 20 Apr 2018 10:34:18 +0530
> Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com> wrote:
> 
>> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
>>
>> Currently the metadata region that holds crash info structure and ELF core
>> header is placed towards the end of reserved memory area. This patch places
>> it at the beginning of the reserved memory area. It also introduces
>> additional dump section called metadata section to communicate location
>> of metadata region to 2nd kernel. This patch also maintains the
>> compatibility between production/capture kernels irrespective of their
>> kernel versions. Both combination older/newer and newer/older works fine.
> 
> Trying to look at the patches it might help me if you document reasons
> for why this change is made changelog, even if it may be obvious to
> someone who knows the code better.

Yeah, I should have mentioned that this patch provides the foundation
for CMA patch 4. With CMA reservation we now allocate metadata region
using cma_alloc() which always allocates metadata region at the start of
CMA reserved region. Earlier in v1, I had this change included along
with CMA reservation patch. But then to make things simpler for review I
did a logical split of movement of metadata region and CMA reservation
patch separately. I think I should order patch 1, 2 and 4 in a sequence
and Move patch3 to patch 1.

> 
> I thought you could include the documentation change in this patch as
> well, but maybe that's a matter of preference.

Yeah that's how I prefer it :-), but that just me. But if it helps in
review I can fold it into 1.

Thanks,
-Mahesh.