Re: [Linux-nvdimm] [PATCH v2 01/20] e820, efi: add ACPI 6.0 persistent memory types
On Tue, Apr 28, 2015 at 1:49 PM, Andy Lutomirski <luto(a)amacapital.net> wrote:
On Tue, Apr 28, 2015 at 11:24 AM, Dan Williams
<dan.j.williams(a)intel.com> wrote:
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 11cc7d54ec3f..d38b53a7e9b2 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -149,6 +149,7 @@ static void __init e820_print_type(u32 type)
> case E820_UNUSABLE:
> printk(KERN_CONT "unusable");
> break;
> + case E820_PMEM:
> case E820_PRAM:
> printk(KERN_CONT "persistent (type %u)", type);
> break;
I'd kind of like to make it more clear what's going on here. It
doesn't help that the spec chose poor names.
How about "NVDIMM physical aperture" for E820_PMEM and "legacy
persistent RAM" for E820_PRAM?
The term "aperture" to me implies this BLK (mmio-windowed) mode of
accessing persistent media that the NFIT specification introduces. In
fact, those ranges are mapped E820_RESERVED. E820_PMEM really is a
memory range that happens to be persistent.
Otherwise this looks generaly sensible, although I don't really
understand why e820_type_to_string and e820_print_type are different.
e820_type_to_string() appears in /proc/iomem and seems to afford
being more descriptive than e820_print_type() that just scrolls by in
dmesg, but I'm just guessing.