clang/ld.lld build fails with `can't create dynamic relocation R_PPC64_ADDR64 against local symbol in readonly segment`

[Michael Ellerman]

Paul Menzel <pmenzel at molgen.mpg.de> writes:
> Am 29.07.21 um 10:23 schrieb Paul Menzel:
>
>> I just wanted to make you aware that building Linux for ppc64le with 
>> clang/lld.ld fails with [1]:
>> 
>>      ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 
>> against symbol: empty_zero_page in readonly segment; recompile object 
>> files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in 
>> the output
>>      >>> defined in arch/powerpc/kernel/head_64.o
>>      >>> referenced by 
>> arch/powerpc/kernel/head_64.o:(___ksymtab+empty_zero_page+0x0)
>> 
>> The patch below from one of the comments [2] fixes it.
>> 
>> --- i/arch/powerpc/Makefile
>> +++ w/arch/powerpc/Makefile
>> @@ -122,7 +122,7 @@ cflags-$(CONFIG_STACKPROTECTOR)     += 
>> -mstack-protector-guard-reg=r2
>>   endif
>> 
>>   LDFLAGS_vmlinux-y := -Bstatic
>> -LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
>> +LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie -z notext
>>   LDFLAGS_vmlinux        := $(LDFLAGS_vmlinux-y)
>>   LDFLAGS_vmlinux += $(call ld-option,--orphan-handling=warn)
>
> Any comments, if this is the right fix? Current Linux master branch 
> still fails to build with `LLVM=1` on Ubuntu 21.04 without this change.

Sorry but I have no idea if it's the right fix. What I need is the
author (or someone else) to send a patch with a change log explaining
the change, what it does, why it's right for llvm, and why it's right
for binutils.

cheers