Re: [Qemu-arm] [RFC PATCH 0/3] add nvdimm support on AArch64 virt platform

[address@hidden]

Hi Peter,

Thanks for your kind comment! I described about NVDIMM briefly below.

> -----Original Message-----
> From: Peter Maydell [mailto:address@hidden
> Sent: Tuesday, July 26, 2016 1:07 AM
> To: 이광우(LEE KWANGWOO) MS SW
> Cc: Xiao Guangrong; Michael S. Tsirkin; Igor Mammedov; Paolo Bonzini; Richard 
> Henderson; Eduardo
> Habkost; Shannon Zhao; Shannon Zhao; QEMU Developers; qemu-arm; 정우석(CHUNG WOO 
> SUK) MS SW; 김현철(KIM
> HYUNCHUL) MS SW
> Subject: Re: [RFC PATCH 0/3] add nvdimm support on AArch64 virt platform
> 
> On 20 July 2016 at 01:49, Kwangwoo Lee <address@hidden> wrote:
> > This patch series add an evaluation environment of NVDIMM on AArch64
> > virt platform. Three parts need to be implemented to make this feature
> > working properly.
> >
> > 1. memory hotplug on arm virt platform
> > 2. configurable ACPI IO base and size both for i386 and arm platform
> > 3. enable NVDIMM on arm virt platform
> >
> > The memory hotplug is required to recognize DIMM type memory and this
> > is also used for NVDIMM device recognition.
> >
> > The ACPI IO base and size need to be changed on creating ACPI NFIT
> > because arm platform uses memory-mapped IO which is different from
> > i386 platform. Thus, this patch set includes the changes of setting
> > ACPI IO base and size during NVDIMM initialization.
> >
> > The last part enables NVDIMM on arm virt platform. The feature is
> > disabled by default. So explicit option - nvdimm=on - is required to
> > enable the feature.
> 
> Thanks for this patchset. Could you provide a brief summary of
> why this is interesting/useful for the benefit of people who don't
> know what an NVDIMM is, please?

NVDIMM stands for Non-Volatile DIMM which has DIMM form factor like PC-DIMM
(Memory Module used in PC) and can be used like a memory, but the stored data
is preserved on power failure. So it can be used as a memory, a storage, or
backup memory on power failure.

NVDIMM-N is already out in the market and Intel, HPE, and other companies
actively developing related software. In Linux kernel, several usages exist
like PMEM, BLK-aperture, and mixed mode. They are actively under developing.

In QEMU, NVDIMM has been emulated on i386 platform. My patch series tries to
enable the environment in AArch64 platform. Related Linux kernel patches were
posted into the mailing list and they are under review/revise process currently.

> thanks
> -- PMM

Best Regards,
Kwangwoo Lee