[PATCH v5 4/6] firmware: Only default FW_PIC to y if supported

[James Clarke]

On 11 Jul 2021, at 05:03, Xiang W <wxjstz at 126.com> wrote:
> 
> 在 2021-07-11星期日的 03:28 +0100，Jessica Clarke写道：
>> Bare-metal GNU ld does not support PIE, so if using it this will
>> result
>> in a failure to build. Instead, default to FW_PIC=n if not supported.
>> Note that an explicit FW_PIC=y is not overriden, to ensure the build
>> fails rather than silently producing a position-dependent binary.
>> 
>> Signed-off-by: Jessica Clarke <jrtc27 at jrtc27.com>
>> ---
>>  Makefile            | 3 +++
>>  firmware/objects.mk | 2 +-
>>  2 files changed, 4 insertions(+), 1 deletion(-)
>> 
>> diff --git a/Makefile b/Makefile
>> index 6b64205..ba06313 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -106,6 +106,9 @@ ifndef PLATFORM_RISCV_XLEN
>>    endif
>>  endif
>>  
>> +# Check whether the linker supports creating PIEs
>> +OPENSBI_LD_PIE := $(shell $(CC) -fPIE -nostdlib -Wl,-pie -x c
>> /dev/null -o /dev/null >/dev/null 2>&1 && echo y || echo n)
> For llvm, --target and -fuse-ld need to be added here. Otherwise, this
> will detect the host instead of what you want

This is patch 4/6, before LLVM support.

Patch 5/6 updates this when adding LLVM support.

Jess

>> +
>>  # Setup list of objects.mk files
>>  ifdef PLATFORM
>>  platform-object-mks=$(shell if [ -d $(platform_src_dir)/ ]; then
>> find $(platform_src_dir) -iname "objects.mk" | sort -r; fi)
>> diff --git a/firmware/objects.mk b/firmware/objects.mk
>> index 3bc83cd..8da7ca3 100644
>> --- a/firmware/objects.mk
>> +++ b/firmware/objects.mk
>> @@ -14,7 +14,7 @@ firmware-asflags-y +=
>>  firmware-ldflags-y +=
>>  
>>  ifndef FW_PIC
>> -FW_PIC := y
>> +FW_PIC := $(OPENSBI_LD_PIE)
>>  endif
>>  
>>  ifeq ($(FW_PIC),y)
>> -- 
>> 2.31.0
>> 
>> 
> 
>