On 26.02.19 00:32, Andre Przywara wrote:
Hi Alex,
On 2/22/19 2:13 AM, Alexander Graf wrote:
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@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?
Ha, that indeed sounds tempting, and actually I tried this before, but it doesn't work. The kernel doc says that an "imply" setting can be overwritten by a direct dependency or a visible prompt. ARM64 is not visible (empty bool), so I figured that introducing this simple symbol is the smallest pain to tackle this issue.
If you say you already did try imply, then I'm all happy :).
Alex