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Date: Fri, 28 Jun 2019 23:08:57 +0530
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Subject: Re: [PATCH v2] powerpc/pseries: Fix maximum memory value
To: Aravinda Prasad <aravinda@linux.vnet.ibm.com>, Nathan Lynch
 <nathanl@linux.ibm.com>
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Nathan Lynch wrote:
> Aravinda Prasad <aravinda@linux.vnet.ibm.com> writes:
>> Calculating the maximum memory based on the number of lmbs
>> and lmb size does not account for the RMA region. Hence
>> use memory_hotplug_max(), which already accounts for the
>> RMA region, to fetch the maximum memory value. Thanks to
>> Nathan Lynch for suggesting the memory_hotplug_max()
>> function.
>=20
> Well, I hope I haven't led you astray... will it give you the desired
> result on a kernel configured without memory hotplug support, booted in
> an LPAR with some huge pages configured?
>=20
> If so, then
> Acked-by: Nathan Lynch <nathanl@linux.ibm.com>
>=20
> It would likely help with review and future maintenance if the semantics
> and intended use of the MaxMem field are made a little more
> explicit. For example, is it supposed to include persistent memory?
> Perhaps a follow-up patch could address this. Or maybe I'm overthinking
> it.

This was primarily aimed to replicate what AIX lparstat does and=20
documentation (*) just says:

  Maximum Memory
      Maximum possible amount of Memory.

I think this mirrors the maximum memory value set in the LPAR profile,=20
and this provides a way to obtain that value from within the LPAR.

This doesn't necessarily answer your question, but that's at least the=20
reference.

(*)=20
https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/com.ibm.aix.cmds3=
/lparstat.htm

- Naveen

=