Re: [PATCH v2 10/39] x86: Create a 32/64-bit selection for the app

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 9/25/21 02:30, Simon Glass wrote:
> Most EFI implementations use 64-bit but U-Boot only supports running as
> a 32-bit app at present. While efi-x86_payload64 does boot from 64-bit
> UEFI it immediately changes back to 32-bit before starting U-Boot.
>
> In order to support a 64-bit U-Boot app, update the Kconfig to add an
> option for 32/64 bit. Update the prompt for the existing option so it is
> clear it relates to the stub. Move both up to just under the choice that
> controls them, since this looks better and the menu.
>
> Use CONFIG_EFI_APP in the Makefile instead of CONFIG_TARGET_EFI_APP,
> since the latter is specific to a single target and we will have two.
>
> Memory size is set to 32MB for now so that it can run on qemu without
> increasing the default memory size. We may need to increase the default
> later.
>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
> Changes in v2:
> - Expand the commit message to make things clearer
>
>   arch/x86/cpu/intel_common/Makefile |  2 +-
>   lib/efi/Kconfig                    | 34 +++++++++++++++++++++++-------
>   2 files changed, 27 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/cpu/intel_common/Makefile b/arch/x86/cpu/intel_common/Makefile
> index 8b9a810f66d..1dc17b45879 100644
> --- a/arch/x86/cpu/intel_common/Makefile
> +++ b/arch/x86/cpu/intel_common/Makefile
> @@ -27,7 +27,7 @@ obj-y += fast_spi.o
>   obj-y += lpc.o
>   obj-y += lpss.o
>   obj-$(CONFIG_$(SPL_)INTEL_GENERIC_WIFI) += generic_wifi.o
> -ifndef CONFIG_TARGET_EFI_APP
> +ifndef CONFIG_EFI_APP
>   obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += microcode.o
>   ifndef CONFIG_$(SPL_)X86_64
>   obj-y += microcode.o
> diff --git a/lib/efi/Kconfig b/lib/efi/Kconfig
> index 93b85644920..e818cef0d15 100644
> --- a/lib/efi/Kconfig
> +++ b/lib/efi/Kconfig
> @@ -26,18 +26,26 @@ config EFI_STUB
>
>   endchoice
>
> -config EFI_RAM_SIZE
> -	hex "Amount of EFI RAM for U-Boot"
> +choice
> +	prompt "EFI app 32/64-bit selection"
>   	depends on EFI_APP
> -	default 0x2000000
>   	help
> -	  Set the amount of EFI RAM which is claimed by U-Boot for its own
> -	  use. U-Boot allocates this from EFI on start-up (along with a few
> -	  other smaller amounts) and it can never be increased after that.
> -	  It is used as the RAM size in with U-Boot.
> +	  EFI does not support mixing 32-bit and 64-bit modes. This is a
> +	  significant problem because it means that you must build a stub with
> +	  the correct type for EFI to load it correctly. If you are using
> +	  32-bit EFI, select 32-bit here, else select 64-bit. Failure to do
> +	  this may produce no error message - it just won't start!
> +
> +config EFI_APP_32BIT
> +	bool "Produce an app for running with 32-bit EFI"
> +
> +config EFI_APP_64BIT
> +	bool "Produce an app for running with 64-bit EFI"
> +
> +endchoice
>
>   choice
> -	prompt "EFI 32/64-bit selection"
> +	prompt "EFI stub 32/64-bit selection"
>   	depends on EFI_STUB
>   	help
>   	  EFI does not support mixing 32-bit and 64-bit modes. This is a
> @@ -53,3 +61,13 @@ config EFI_STUB_64BIT
>   	bool "Produce a stub for running with 64-bit EFI"
>
>   endchoice
> +
> +config EFI_RAM_SIZE
> +	hex "Amount of EFI RAM for U-Boot"
> +	depends on EFI_APP
> +	default 0x2000000

This will be too small for loading the kernel and the initrd in some
cases. 256 MiB seems reasonable.

Best regards

Heinrich

> +	help
> +	  Set the amount of EFI RAM which is claimed by U-Boot for its own
> +	  use. U-Boot allocates this from EFI on start-up (along with a few
> +	  other smaller amounts) and it can never be increased after that.
> +	  It is used as the RAM size in with U-Boot.
>