On Thu, Jun 9, 2016 at 10:42 AM, Yigal Korman <yigal@xxxxxxxxxxxxx> wrote: > The 'efi_legacy_pmem' parameter will convert EFI persistent memory range > (type 14) into E820 legacy NVDIMM (type 12) memory range. > > Background: > > In contrast with the NVDIMM E820 types where we can clearly distinguish > between old NVDIMMs (type-12) and ACPI 6.0 NVDIMMs (type-7), the EFI > memory types for NVDIMMs are the same before ACPI 6.0 and after > (type-14). > This means that old NVDIMMs under EFI aren't supported even though > they work fine if booted with BIOS (E820). > > So allow the user to explicitly request the kernel to identify NVDIMMs > as legacy under EFI. > I'm concerned with the potential for this command line parameter to collide with NFIT defined ranges. At a minimum it should confirm that there is not already an NFIT describing the same address ranges. However, we have the ability to override / inject ACPI tables and methods from the kernel. Why not use that facility to custom craft an NFIT when the BIOS fails to provide one? That way EFI type-14 maintains a constant interpretation as just a reserved memory range with no other side effects. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
