[U-Boot] [PATCH 6/9] sunxi: allow 32-bit builds for 64-bit SoCs

[Alexander Graf]

On 21.02.19 02:30, Andre Przywara wrote:
> At the moment we build the SPL and U-Boot proper for the 64-bit AArch64
> instruction set. But since the cores provide an AArch32 compatibility mode
> and in fact the BootROM runs in 32-bit mode, it can be useful to have at
> least the SPL run in AArch32 as well. This has two advantages:
> - As AArch32 features the compact Thumb2 instruction encoding, we can
>   get a much smaller image size, which is a relief for our SPL.
> - Staying in AArch32, with the MMU turned off, allows an easy return to
>   the BootROM and its FEL mode. This enables FEL booting on those SoCs.
> 
> Introduce a Kconfig option which toggles between CONFIG_ARM64 and
> CONFIG_CPU_V7A, to allow easy switching between the two modes. This can
> be manually selected in menuconfig, but follow-up patches will introduce
> a separate defconfig for that purpose.
> 
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
>  arch/arm/mach-sunxi/Kconfig | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
> index 74e234cded..347d737fd0 100644
> --- a/arch/arm/mach-sunxi/Kconfig
> +++ b/arch/arm/mach-sunxi/Kconfig
> @@ -146,6 +146,10 @@ config SUNXI_DRAM_MAX_SIZE
>  	default 0xC0000000 if MACH_SUN50I || MACH_SUN50I_H5 || MACH_SUN50I_H6
>  	default 0x80000000
>  
> +config SUNXI_ARMV8_32BIT_BUILD
> +	bool "Build 32-bit binaries for ARMv8 SoCs"
> +	default n
> +
>  choice
>  	prompt "Sunxi SoC Variant"
>  	optional
> @@ -275,7 +279,8 @@ config MACH_SUN9I
>  
>  config MACH_SUN50I
>  	bool "sun50i (Allwinner A64)"
> -	select ARM64
> +	select ARM64 if !SUNXI_ARMV8_32BIT_BUILD

Can't you make this "imply ARM64" instead and then just set
ARM64=n;CPU_V7A=y in the defconfig?


Alex

> +	select CPU_V7A if SUNXI_ARMV8_32BIT_BUILD
>  	select DM_I2C
>  	select PHY_SUN4I_USB
>  	select SUN6I_PRCM
> @@ -291,14 +296,16 @@ config MACH_SUN50I
>  
>  config MACH_SUN50I_H5
>  	bool "sun50i (Allwinner H5)"
> -	select ARM64
> +	select ARM64 if !SUNXI_ARMV8_32BIT_BUILD
> +	select CPU_V7A if SUNXI_ARMV8_32BIT_BUILD
>  	select MACH_SUNXI_H3_H5
>  	select FIT
>  	select SPL_LOAD_FIT
>  
>  config MACH_SUN50I_H6
>  	bool "sun50i (Allwinner H6)"
> -	select ARM64
> +	select ARM64 if !SUNXI_ARMV8_32BIT_BUILD
> +	select CPU_V7A if SUNXI_ARMV8_32BIT_BUILD
>  	select SUPPORT_SPL
>  	select FIT
>  	select SPL_LOAD_FIT
>