Re: [edk2-devel] [edk2-platforms][PATCH v3 5/5] Platform/RPi3/PlatformSmbiosDxe: Derive RAM size from board revision

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Pete,

On 10/11/19 1:07 PM, Pete Batard wrote:
> The board revision is the proper channel to use to detect the amount of
> RAM available as bits [20-22] report the effective RAM size for the board
> starting with 256 MB (000b) and doubling in size for each value.
> 
> Signed-off-by: Pete Batard <pete@akeo.ie>
> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
>   Platform/RaspberryPi/RPi3/Drivers/PlatformSmbiosDxe/PlatformSmbiosDxe.c | 18 ++++++++++++------
>   1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/Platform/RaspberryPi/RPi3/Drivers/PlatformSmbiosDxe/PlatformSmbiosDxe.c b/Platform/RaspberryPi/RPi3/Drivers/PlatformSmbiosDxe/PlatformSmbiosDxe.c
> index b5dcff897a59..5abc82b8d363 100644
> --- a/Platform/RaspberryPi/RPi3/Drivers/PlatformSmbiosDxe/PlatformSmbiosDxe.c
> +++ b/Platform/RaspberryPi/RPi3/Drivers/PlatformSmbiosDxe/PlatformSmbiosDxe.c
> @@ -866,16 +866,22 @@ MemArrMapInfoUpdateSmbiosType19 (
>     )
>   {
>     EFI_STATUS Status;
> -  UINT32 Base;
> -  UINT32 Size;
> +  UINT32 BoardRevision = 0;
>   
> -  Status = mFwProtocol->GetArmMem (&Base, &Size);
> +  // Note: Type 19 addresses are expressed in KB, not bytes
> +  mMemArrMapInfoType19.StartingAddress = 0;

Now you assume the ARM base RAM address is always 0, why?

> +  // The minimum RAM size used on any Raspberry Pi model is 256 MB
> +  mMemArrMapInfoType19.EndingAddress = 256 * 1024;
> +  Status = mFwProtocol->GetModelRevision (&BoardRevision);
>     if (Status != EFI_SUCCESS) {
> -    DEBUG ((DEBUG_ERROR, "Couldn't get the ARM memory size: %r\n", Status));
> +    DEBUG ((DEBUG_WARNING, "Couldn't get the board memory size - defaulting to 256 MB: %r\n", Status));
>     } else {
> -    mMemArrMapInfoType19.StartingAddress = Base / 1024;
> -    mMemArrMapInfoType19.EndingAddress = (Base + Size - 1) / 1024;
> +    // www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/README.md
> +    // Bits [20-22] indicate the amount of memory starting with 256MB (000b)
> +    // and doubling in size for each value (001b = 512 MB, 010b = 1GB, etc.)
> +    mMemArrMapInfoType19.EndingAddress <<= (BoardRevision >> 20) & 0x07;
>     }
> +  mMemArrMapInfoType19.EndingAddress -= 1;
>   
>     LogSmbiosData ((EFI_SMBIOS_TABLE_HEADER*)&mMemArrMapInfoType19, mMemArrMapInfoType19Strings, NULL);
>   }
>