[PATCH v2 1/2] fadump: reduce memory consumption for capture kernel

[Hari Bathini]

On Wednesday 19 April 2017 07:38 PM, Michal Suchánek wrote:
> On Wed, 19 Apr 2017 14:19:47 +1000
> Michael Ellerman <mpe at ellerman.id.au> wrote:
>
>> Michal Suchánek <msuchanek at suse.de> writes:
>>> On Mon, 17 Apr 2017 20:43:02 +0530
>>> Hari Bathini <hbathini at linux.vnet.ibm.com> wrote:
>>>> On Friday 14 April 2017 01:28 AM, Michal Suchánek wrote:
>>>>> more (optional) properties cannot be added?
>>>> Kernel change seems simple over f/w enhancement..
>>> That certainly looks so when you are a kernel developer and can
>>> implement the change yourself compared to convincing some firmware
>>> developer that this feature makes sense.
>>>
>>> On the other hand, the proposed kernel-only solution introduces
>>> requirement that the maintainer does not like.
>>>
>>> For the platform as a whole does it make more sense to add a hack to
>>> the kernel or does it make sense to enhance the firmware to provide
>>> more options for firmware-assisted dump?
>> Unfortunately it doesn't really matter, because there is firmware out
>> there that implements the current behaviour and will never be updated.
>> So we have to work with what's there.
>>
> It's not that with the existing firmware fadump does not work. It just
> uses more memory than needed. So if new firmware revision allows more
> flexibility it will work for people with updated firmware and people
> with outdated firmware will get the current behavior.
>
> The memory saving is only significant for big systems so only people
> running those will get significant improvement from the updated
> firmware.
>


Hi Michal,

With the fadump_append= approach I posted in this response thread,
additional parameters are enforced when fadump is active. If f/w supports
appending additional parameters, it has to update chosen/bootargs
whenever fadump is active. Almost the same thing except the dirty job
is now done by f/w? Hence I thought fadump_append= kernel parameter
approach is simple and lesser of the two evils? Am i missing something 
here..

Thanks
Hari