[U-Boot] [PATCH v2 14/14] u-boot.elf: build it for every arch

[Daniel Schwierzeck]

+cc more people involved with ARM

note: purpose of this patch is to provide an u-boot.elf binary for
Broadcom MIPS platforms by re-using the already existing Makefile target
for aarch64. This u-boot.elf binary should be used as a stage 2 loader
until U-Boot can be replace the original Broadcom boot loader.

Am 16.04.2017 um 00:04 schrieb Álvaro Fernández Rojas:
> ARM64 isn't the only arch that needs it, since BMIPS CFE supports loading .elf
> images instead of raw binaries.
> 
> Signed-off-by: Álvaro Fernández Rojas <noltari at gmail.com>
> ---
>  v2: Introduce changes suggested by Daniel Schwierzeck:
>   - Avoid using a linker script.
>   - Reuse aarch64 u-boot.elf generation for other archs.
>   - Fix _start vs __start symbol.
> 
>  Makefile | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 8d4e605..8093a6b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -747,6 +747,9 @@ BOARD_SIZE_CHECK =
>  endif
>  
>  # Statically apply RELA-style relocations (currently arm64 only)
> +# This is useful for arm64 where static relocation needs to be performed on
> +# the raw binary, but certain simulators only accept an ELF file (but don't
> +# do the relocation).
>  ifneq ($(CONFIG_STATIC_RELA),)
>  # $(1) is u-boot ELF, $(2) is u-boot bin, $(3) is text base
>  DO_STATIC_RELA = \
> @@ -758,7 +761,8 @@ DO_STATIC_RELA =
>  endif
>  
>  # Always append ALL so that arch config.mk's can add custom ones
> -ALL-y += u-boot.srec u-boot.bin u-boot.sym System.map binary_size_check
> +ALL-y += u-boot.srec u-boot.bin u-boot.elf u-boot.sym
> +ALL-y += System.map binary_size_check
>  
>  ALL-$(CONFIG_ONENAND_U_BOOT) += u-boot-onenand.bin
>  ifeq ($(CONFIG_SPL_FSL_PBL),y)
> @@ -785,7 +789,6 @@ ALL-$(CONFIG_OF_HOSTFILE) += u-boot.dtb
>  ifneq ($(CONFIG_SPL_TARGET),)
>  ALL-$(CONFIG_SPL) += $(CONFIG_SPL_TARGET:"%"=%)
>  endif
> -ALL-$(CONFIG_REMAKE_ELF) += u-boot.elf

the current behaviour shouldn't be changed where u-boot.elf is only
built when requested by a board

>  ALL-$(CONFIG_EFI_APP) += u-boot-app.efi
>  ALL-$(CONFIG_EFI_STUB) += u-boot-payload.efi
>  
> @@ -1180,16 +1183,18 @@ OBJCOPYFLAGS_u-boot-img-spl-at-end.bin := -I binary -O binary \
>  u-boot-img-spl-at-end.bin: u-boot.img spl/u-boot-spl.bin FORCE
>  	$(call if_changed,pad_cat)
>  
> -# Create a new ELF from a raw binary file.  This is useful for arm64
> -# where static relocation needs to be performed on the raw binary,
> -# but certain simulators only accept an ELF file (but don't do the
> -# relocation).
> +# Create a new ELF from a raw binary file.
>  # FIXME refactor dts/Makefile to share target/arch detection
> +ifdef CONFIG_64BIT
> +O_FORMAT := $(shell $(OBJDUMP) -i | head -2 | grep elf64)
> +else
> +O_FORMAT := $(shell $(OBJDUMP) -i | head -2 | grep elf32)
> +endif

this should be set in arch/ARCH/config.mk. Also this is already
contained in OBJCOPYFLAGS. Either we can filter out the value for -O
from OBJCOPYFLAGS or we define an extra variable like PLATFORM_ELFFLAGS
or OBJCOPYFLAGS_ELF where we assign the values for -B and -O.

For example:
--- a/arch/mips/config.mk
+++ b/arch/mips/config.mk
@@ -36,6 +36,7 @@ OBJCOPYFLAGS          += -O $(64bit-bfd)
 endif

 PLATFORM_CPPFLAGS += -D__MIPS__
+PLATFORM_ELFFLAGS += -B mips $(OBJCOPYFLAGS)


--- a/arch/arm/config.mk
+++ b/arch/arm/config.mk
@@ -30,6 +30,12 @@ PLATFORM_RELFLAGS    += $(LLVM_RELFLAGS)

 PLATFORM_CPPFLAGS += -D__ARM__

+ifdef CONFIG_ARM64
+PLATFORM_ELFFLAGS += -B aarch64 -O elf64-littleaarch64
+else
+PLATFORM_ELFFLAGS += -B arm -O elf32-littlearm
+endif



>  u-boot.elf: u-boot.bin
> -	@$(OBJCOPY)  -B aarch64 -I binary -O elf64-littleaarch64 \
> +	@$(OBJCOPY) -B $(ARCH) -I binary -O $(O_FORMAT) \
>  		$< u-boot-elf.o
>  	@$(LD) u-boot-elf.o -o $@ \
> -		--defsym=_start=$(CONFIG_SYS_TEXT_BASE) \
> +		--defsym=__start=$(CONFIG_SYS_TEXT_BASE) \

I'm not sure but changing to __start for all could break aarch64 boards.

>  		-Ttext=$(CONFIG_SYS_TEXT_BASE)
>  
>  # Rule to link u-boot
> 

-- 
- Daniel

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