RE: grub causing NVDIMMs to be treated as normal memory

[Elliott, Robert (Persistent Memory)]

> -----Original Message-----
> From: Linux-nvdimm [mailto:address@hidden On
> Behalf Of Andrei Borzenkov
> Sent: Wednesday, November 25, 2015 12:37 PM
> To: The development of GNU GRUB <address@hidden>;
> address@hidden; address@hidden
> Subject: Re: grub causing NVDIMMs to be treated as normal memory
> 
> 25.11.2015 02:52, Elliott, Robert (Persistent Memory) пишет:
> > 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, which marks the memory range
> > as GRUB_MEMORY_AVAILABLE and ends up in e820 as regular memory.
> 
> Could you test if attached patch works for you (compile tested)?

Thanks.

I think I finally got that to compile with
    configure --with-platform=efi
    make

but have no clue how to install it and try it out.  I'm using a
fedora22 system, which has its own /sbin/grub2-install.  I 
don't understand how that differs from the grub-install in the
build directory or how to get either of them to work.

Anyway, we should create another patch that does:
* #define GRUB_EFI_PERSISTENT_MEMORY 14 per UEFI 2.5
* #define GRUB_E820_PERSISTENT_MEMORY 7 per ACPI 6.0
* add a GRUB_MEMORY_PMEM enum
* map GRUB_EFI_PERSISTENT_MEMORY -> GRUM_PMEMORY_MEM 
  -> GRUB_E820_PERSISTENT_MEMORY per ACPI 6.0

to explicitly handle the new types (in addition to handling
unknown values correctly).


---
Robert Elliott, HPE Persistent Memory