Re: [PATCH 01/21] e820, efi: add ACPI 6.0 persistent memory types

[Andy Lutomirski]

On Fri, Apr 17, 2015 at 6:35 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> ACPI 6.0 formalizes e820-type-7 and efi-type-14 as persistent memory.
> Mark it "reserved" and allow it to be claimed by a persistent memory
> device driver.
>
> This definition is in addition to the Linux kernel's existing type-12
> definition that was recently added in support of shipping platforms with
> NVDIMM support that predate ACPI 6.0 (which now classifies type-12 as
> OEM reserved).  We may choose to exploit this wealth of definitions for
> NVDIMMs to differentiate E820_PRAM (type-12) from E820_PMEM (type-7).
> One potential differentiation is that PMEM is not backed by struct page
> by default in contrast to PRAM.  For now, they are effectively treated
> as aliases by the mm.
>
> Note, /proc/iomem can be consulted for differentiating legacy
> "Persistent RAM" E820_PRAM vs standard "Persistent I/O Memory"
> E820_PMEM.
>

Looks reasonable.  Time to ask my vendor if they can give me ACPI
6.0-compliant firmware.

--Andy

> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> ---
>  arch/arm64/kernel/efi.c          |    1 +
>  arch/ia64/kernel/efi.c           |    1 +
>  arch/x86/boot/compressed/eboot.c |    4 ++++
>  arch/x86/include/uapi/asm/e820.h |    1 +
>  arch/x86/kernel/e820.c           |   25 +++++++++++++++++++------
>  arch/x86/platform/efi/efi.c      |    3 +++
>  include/linux/efi.h              |    3 ++-
>  7 files changed, 31 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index ab21e0d58278..9d4aa18f2a82 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -158,6 +158,7 @@ static __init int is_reserve_region(efi_memory_desc_t *md)
>         case EFI_BOOT_SERVICES_CODE:
>         case EFI_BOOT_SERVICES_DATA:
>         case EFI_CONVENTIONAL_MEMORY:
> +       case EFI_PERSISTENT_MEMORY:
>                 return 0;
>         default:
>                 break;
> diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
> index c52d7540dc05..cd8b7485e396 100644
> --- a/arch/ia64/kernel/efi.c
> +++ b/arch/ia64/kernel/efi.c
> @@ -1227,6 +1227,7 @@ efi_initialize_iomem_resources(struct resource *code_resource,
>                         case EFI_RUNTIME_SERVICES_CODE:
>                         case EFI_RUNTIME_SERVICES_DATA:
>                         case EFI_ACPI_RECLAIM_MEMORY:
> +                       case EFI_PERSISTENT_MEMORY:
>                         default:
>                                 name = "reserved";
>                                 break;
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index ef17683484e9..dde5bf7726f4 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -1222,6 +1222,10 @@ static efi_status_t setup_e820(struct boot_params *params,
>                         e820_type = E820_NVS;
>                         break;
>
> +               case EFI_PERSISTENT_MEMORY:
> +                       e820_type = E820_PMEM;
> +                       break;
> +
>                 default:
>                         continue;
>                 }
> diff --git a/arch/x86/include/uapi/asm/e820.h b/arch/x86/include/uapi/asm/e820.h
> index 960a8a9dc4ab..0f457e6eab18 100644
> --- a/arch/x86/include/uapi/asm/e820.h
> +++ b/arch/x86/include/uapi/asm/e820.h
> @@ -32,6 +32,7 @@
>  #define E820_ACPI      3
>  #define E820_NVS       4
>  #define E820_UNUSABLE  5
> +#define E820_PMEM      7
>
>  /*
>   * This is a non-standardized way to represent ADR or NVDIMM regions that
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 11cc7d54ec3f..410af501a941 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -137,6 +137,8 @@ static void __init e820_print_type(u32 type)
>         case E820_RESERVED_KERN:
>                 printk(KERN_CONT "usable");
>                 break;
> +       case E820_PMEM:
> +       case E820_PRAM:
>         case E820_RESERVED:
>                 printk(KERN_CONT "reserved");
>                 break;
> @@ -149,9 +151,6 @@ static void __init e820_print_type(u32 type)
>         case E820_UNUSABLE:
>                 printk(KERN_CONT "unusable");
>                 break;
> -       case E820_PRAM:
> -               printk(KERN_CONT "persistent (type %u)", type);
> -               break;
>         default:
>                 printk(KERN_CONT "type %u", type);
>                 break;
> @@ -919,10 +918,26 @@ static inline const char *e820_type_to_string(int e820_type)
>         case E820_NVS:  return "ACPI Non-volatile Storage";
>         case E820_UNUSABLE:     return "Unusable memory";
>         case E820_PRAM: return "Persistent RAM";
> +       case E820_PMEM: return "Persistent I/O Memory";
>         default:        return "reserved";
>         }
>  }
>
> +static bool do_mark_busy(u32 type, struct resource *res)
> +{
> +       if (res->start < (1ULL<<20))
> +               return true;
> +
> +       switch (type) {
> +       case E820_RESERVED:
> +       case E820_PRAM:
> +       case E820_PMEM:
> +               return false;
> +       default:
> +               return true;
> +       }
> +}
> +
>  /*
>   * Mark e820 reserved areas as busy for the resource manager.
>   */
> @@ -952,9 +967,7 @@ void __init e820_reserve_resources(void)
>                  * pci device BAR resource and insert them later in
>                  * pcibios_resource_survey()
>                  */
> -               if (((e820.map[i].type != E820_RESERVED) &&
> -                    (e820.map[i].type != E820_PRAM)) ||
> -                    res->start < (1ULL<<20)) {
> +               if (do_mark_busy(e820.map[i].type, res)) {
>                         res->flags |= IORESOURCE_BUSY;
>                         insert_resource(&iomem_resource, res);
>                 }
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index dbc8627a5cdf..a116e236ac3f 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -145,6 +145,9 @@ static void __init do_add_efi_memmap(void)
>                 case EFI_UNUSABLE_MEMORY:
>                         e820_type = E820_UNUSABLE;
>                         break;
> +               case EFI_PERSISTENT_MEMORY:
> +                       e820_type = E820_PMEM;
> +                       break;
>                 default:
>                         /*
>                          * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index cf7e431cbc73..28868504aa17 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -85,7 +85,8 @@ typedef       struct {
>  #define EFI_MEMORY_MAPPED_IO           11
>  #define EFI_MEMORY_MAPPED_IO_PORT_SPACE        12
>  #define EFI_PAL_CODE                   13
> -#define EFI_MAX_MEMORY_TYPE            14
> +#define EFI_PERSISTENT_MEMORY          14
> +#define EFI_MAX_MEMORY_TYPE            15
>
>  /* Attribute values: */
>  #define EFI_MEMORY_UC          ((u64)0x0000000000000001ULL)    /* uncached */
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
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