Re: [RFC][PATCH v2 01/21] e820: cheat PMEM as DRAM

[Fengguang Wu]

On Wed, Dec 26, 2018 at 07:41:41PM -0800, Matthew Wilcox wrote:
> On Wed, Dec 26, 2018 at 09:14:47PM +0800, Fengguang Wu wrote:
> > From: Fan Du <fan.du@xxxxxxxxx>
> >
> > This is a hack to enumerate PMEM as NUMA nodes.
> > It's necessary for current BIOS that don't yet fill ACPI HMAT table.
> >
> > WARNING: take care to backup. It is mutual exclusive with libnvdimm
> > subsystem and can destroy ndctl managed namespaces.
>
> Why depend on firmware to present this "correctly"?  It seems to me like
> less effort all around to have ndctl label some namespaces as being for
> this kind of use.

Dave Hansen may be more suitable to answer your question. He posted
patches to make PMEM NUMA node coexist with libnvdimm and ndctl:

[PATCH 0/9] Allow persistent memory to be used like normal RAM
https://lkml.org/lkml/2018/10/23/9

That depends on future BIOS. So we did this quick hack to test out
PMEM NUMA node for the existing BIOS.

Thanks,
Fengguang