Re: [Linux-nvdimm] [PATCH v2 11/20] libnd, nd_pmem: add libnd support to the pmem driver
On Tue, Apr 28, 2015 at 2:04 PM, Andy Lutomirski <luto(a)amacapital.net> wrote:
On Tue, Apr 28, 2015 at 11:25 AM, Dan Williams
<dan.j.williams(a)intel.com> wrote:
> +config ND_E820
> + tristate "E820: Support the E820-type-12 PMEM convention"
> + depends on X86_PMEM_LEGACY
> + default m if X86_PMEM_LEGACY
> + select LIBND
> + help
> + Prior to ACPI 6 some platforms advertised peristent memory
> + via type-12 e820 memory ranges. Create a libnd bus and
> + attach an instance of the pmem driver to these ranges.
> +
How about something like:
"This driver allows libnd to work with legacy, pre-ACPI 6 NVDIMMs.
This enables such devices to be exposed as block devices using PMEM.
The legacy NVDIMM interface is problematic. This driver will not work
if you boot using UEFI, and some NVDIMMs and motherboards that work
with this driver may require proprietary code in order to work
reliably."
Perhaps not "problematic" but "requires a BIOS in Legacy mode"
It might also mention that if you use the kernel command line
memmap=nn!ss syntax it adds
a type 12 region to the e820 map and so you would want this support.
If you have a motherboard with UEFI support for NVDIMM's that would be
the recommended
configuration.
Phil P.
--
Philip Pokorny, RHCE
Chief Technology Officer
PENGUIN COMPUTING, Inc
www.penguincomputing.com