[PATCH] efi_loader: Increase default variable store size to 128K

[Heinrich Schuchardt]

On 11/6/23 16:47, Ilias Apalodimas wrote:
> In commit 9fd3f881c6ed ("efi_loader: Increase default variable store size to 64KiB")
> Alper has a detailed explanation of why the size needs to be bumped to at
> least 64K.  However enabling Secure boot, writing db, KEK, PK etc keys
> will further increase the size so bump it to 128K.
>
> It's worth noting that when U-Boot stores the EFI variables in an RPMB the
> available storage is defined statically in StandAloneMM at build time.
> The U-Boot code is detecting the available true size on the fly during
> writes. When StandAloneMM is present this size defines the reserved
> memory U-Boot can use to copy any runtime variables, before booting an
> OS.
>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

> ---
>   lib/efi_loader/Kconfig | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index 4ccd26f94a93..0d024911b42e 100644
> --- a/lib/efi_loader/Kconfig
> +++ b/lib/efi_loader/Kconfig
> @@ -133,18 +133,20 @@ endif
>
>   config EFI_VAR_BUF_SIZE
>   	int "Memory size of the UEFI variable store"
> -	default 16384 if EFI_MM_COMM_TEE
> -	default 65536
> +	default 131072
>   	range 4096 2147483647
>   	help
>   	  This defines the size in bytes of the memory area reserved for keeping
>   	  UEFI variables.
>
> -	  When using StandAloneMM (CONFIG_EFI_MM_COMM_TEE=y) this value should
> -	  match the value of PcdFlashNvStorageVariableSize used to compile the
> -	  StandAloneMM module.
> +	  When using StandAloneMM (CONFIG_EFI_MM_COMM_TEE=y) is used the
> +	  available size for storing variables is defined in
> +	  PcdFlashNvStorageVariableSize.
> +	  That value is probed at runtime from U-Boot. In that case,
> +	  EFI_VAR_BUF_SIZE represents the memory U-Boot reserves to present
> +	  runtime variables to the OS.
>
> -	  Minimum 4096, default 65536, or 16384 when using StandAloneMM.
> +	  Minimum 4096, default 131072
>
>   config EFI_GET_TIME
>   	bool "GetTime() runtime service"
> --
> 2.40.1
>