Re: [RFC PATCH 6/7] ArmVirtPkg/MemoryInitPeiLib: split memory HOB based on MAX_ALLOC_ADDRESS

[Laszlo Ersek <lersek@redhat.com>]

On 12/07/18 12:23, Ard Biesheuvel wrote:
> The current ArmVirtMemoryInitPeiLib code splits the memory region passed
> via PcdSystemMemoryBase/PcdSystemMemorySize in two if the region extends
> beyond the MAX_ADDRESS limit. This was introduced for 32-bit ARM, which
> may support more than 4 GB of physical address space, but cannot address
> all of it via a 1:1 mapping, and a single region that is not mappable
> in its entirety is unusable by the PEI core.
> 
> AArch64 is in a similar situation now: platforms may support more than
> 256 TB of physical address space, but only 256 TB is addressable by the
> CPU, and so a memory region that extends from below this limit to above
> it should be split.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> index 05afd1282422..66925fc05ebd 100644
> --- a/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> +++ b/ArmVirtPkg/Library/ArmVirtMemoryInitPeiLib/ArmVirtMemoryInitPeiLib.c
> @@ -75,18 +75,18 @@ MemoryPeim (
>    SystemMemoryTop = PcdGet64 (PcdSystemMemoryBase) +
>                      PcdGet64 (PcdSystemMemorySize);
>  
> -  if (SystemMemoryTop - 1 > MAX_ADDRESS) {
> +  if (SystemMemoryTop - 1 > MAX_ALLOC_ADDRESS) {
>      BuildResourceDescriptorHob (
>          EFI_RESOURCE_SYSTEM_MEMORY,
>          ResourceAttributes,
>          PcdGet64 (PcdSystemMemoryBase),
> -        (UINT64)MAX_ADDRESS - PcdGet64 (PcdSystemMemoryBase) + 1
> +        (UINT64)MAX_ALLOC_ADDRESS - PcdGet64 (PcdSystemMemoryBase) + 1
>          );
>      BuildResourceDescriptorHob (
>          EFI_RESOURCE_SYSTEM_MEMORY,
>          ResourceAttributes,
> -        (UINT64)MAX_ADDRESS + 1,
> -        SystemMemoryTop - MAX_ADDRESS - 1
> +        (UINT64)MAX_ALLOC_ADDRESS + 1,
> +        SystemMemoryTop - MAX_ALLOC_ADDRESS - 1
>          );
>    } else {
>      BuildResourceDescriptorHob (
> 

Looks correct to me.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>