Re: grub causing NVDIMMs to be treated as normal memory

[Andrei Borzenkov]

On Wed, Nov 25, 2015 at 2:52 AM, Elliott, Robert (Persistent Memory)
<address@hidden> wrote:
> We've noticed that some combinations of grub and old linux kernels
>
> end up interpreting the UEFI memory map EfiPersistentMemory type 14
>
> (formerly a reserved value) as regular memory in the linux e820
>
> table, causing silent data corruption on the NVDIMMs.  That occurs
>
> even though grub prints this message suggesting everything is safe:
>
>     Unknown memory type 14, considering reserved
>
>
>
> In broken versions of grub, the code parsing the UEFI memory map
>
> has a "default" case that falls through to the
>
> GRUB_EFI_BOOT_SERVICES_DATA case,

This is fallout of 9be4c45dbe3c877d1f4856e99ee15133c6cd2261; thank you
for report!

> which marks the memory range
>
> as GRUB_MEMORY_AVAILABLE and ends up in e820 as regular memory.
>

According to EFI spec, EfiPersistentMemory is "A memory region that
operates as EfiConventionalMemory". Why it should be treated
differently?