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

[Simon Glass]

Hi Bin,

On 23 July 2015 at 05:07, Bin Meng <bmeng.cn at gmail.com> wrote:
> 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.

I'll add a comment - it is used in the top-level Makefile.

> - 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?

By the time we do the objcopy these have been removed by the previous
link step. I don't think we need them.

>
>> +
>> +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

Regards,
Simon