[PATCH] D30256: [ELF] - Implemented -z noreloc-overflow.

[George Rimar via llvm-commits]

>That is a really odd name if that is what it does. What fails to link if
>you just ignore the option?
>
>Cheers,
>Rafael

Currently LLD links kernel fine because next lines that used as check:

LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
	&& echo "-z noreloc-overflow -pie --no-dynamic-linker")

never work for us, so build system does not add
-z noreloc-overflow -pie --no-dynamic-linker to invokation.
That works now because KASLR is disabled (kernel does not execute self relocation code).

But when I take reproduce and ignore that option then BFD output for reproduce is:
/usr/bin/ld: home/umb/linux_kernel/linux/linux/arch/x86/boot/compressed/head_64.o: relocation R_X86_64_32 against symbol `z_input_len' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Nonrepresentable section on output

I think generally this option is used just to skip all possible checks for dynamic relocations and let the
user of output to do all job on his side.

George.