[U-Boot] [PATCH 30/48] x86: Set up tool chain flags for running as EFI application

[Bin Meng]

Hi Simon,

I think this patch should come before patch#22 in which it refers to
OBJCOPYFLAGS_EFI defined in this patch. More comments below.

On Wed, Jul 22, 2015 at 11:49 PM, Simon Glass <sjg at chromium.org> wrote:
> From: Ben Stoltz <stoltz at google.com>
>
> Adjust the tool chain flags to build U-Boot as a relocatable shared library,

Nits: toolchain

> as required by EFI.
>
> Signed-off-by: Ben Stoltz <stoltz at google.com>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>  arch/x86/config.mk | 35 ++++++++++++++++++++++++++++++++---
>  1 file changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/config.mk b/arch/x86/config.mk
> index 999143e..bb0b254 100644
> --- a/arch/x86/config.mk
> +++ b/arch/x86/config.mk
> @@ -8,19 +8,48 @@
>  CONFIG_STANDALONE_LOAD_ADDR ?= 0x40000
>
>  PLATFORM_CPPFLAGS += -fno-strict-aliasing
> -PLATFORM_CPPFLAGS += -mregparm=3
>  PLATFORM_CPPFLAGS += -fomit-frame-pointer
>  PF_CPPFLAGS_X86   := $(call cc-option, -fno-toplevel-reorder, \
>                        $(call cc-option, -fno-unit-at-a-time)) \
>                      $(call cc-option, -mpreferred-stack-boundary=2)
> +
>  PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_X86)
>  PLATFORM_CPPFLAGS += -fno-dwarf2-cfi-asm
>  PLATFORM_CPPFLAGS += -march=i386 -m32
>
>  PLATFORM_RELFLAGS += -ffunction-sections -fvisibility=hidden
>
> -PLATFORM_LDFLAGS += --emit-relocs -Bsymbolic -Bsymbolic-functions -m elf_i386
> +PLATFORM_LDFLAGS += -Bsymbolic -Bsymbolic-functions
>
> -LDFLAGS_FINAL += --gc-sections -pie
>  LDFLAGS_FINAL += --wrap=__divdi3 --wrap=__udivdi3
>  LDFLAGS_FINAL += --wrap=__moddi3 --wrap=__umoddi3
> +
> +LDFLAGS_EFI := -Bsymbolic -Bsymbolic-functions -znocombreloc -shared \
> +       --no-undefined

- Where is this referenced?
- It has duplicated options like '-Bsymbolic -Bsymbolic-functions'
which are already in PLATFORM_LDFLAGS.
- Is 'znocombreloc' a must for U-Boot? It is not in the original gnu-efi codes.

> +
> +OBJCOPYFLAGS_EFI := -j .text -j .sdata -j .data -j .dynamic -j .dynsym \
> +       -j .rel -j .rela -j .reloc

Should we add wildcard section names as well, like the original gnu-efi codes?

> +
> +CFLAGS_NON_EFI := -mregparm=3
> +CFLAGS_EFI := -fpic -fshort-wchar $(call cc-option, -mno-red-zone)

no-red-zone is only needed for x86_64. The cc-option only tests if
compiler supports this, but it does not know if it is compiled against
x86 or x64 codes.

> +
> +EFIARCH=ia32
> +
> +LDSCRIPT_EFI := $(srctree)/$(CPUDIR)/efi/elf_$(EFIARCH)_efi.lds
> +OBJCOPYFLAGS_EFI += --target=efi-app-$(EFIARCH)
> +
> +ifeq ($(CONFIG_ARCH_EFI),y)
> +
> +PLATFORM_CPPFLAGS += $(CFLAGS_EFI)
> +PLATFORM_LDFLAGS += -m elf_i386
> +LDFLAGS_FINAL += -znocombreloc -shared
> +OBJCOPYFLAGS_EFI += --target=efi-app-$(EFIARCH)

Duplicated. Already has this in above lines.

> +LDSCRIPT := $(LDSCRIPT_EFI)
> +
> +else
> +
> +PLATFORM_CPPFLAGS += $(CFLAGS_NON_EFI)
> +PLATFORM_LDFLAGS += --emit-relocs -m elf_i386
> +LDFLAGS_FINAL += --gc-sections -pie
> +
> +endif
> --

Regards,
Bin