[llvm-dev] Linking android with lld: aarch64 target

[Peter Smith via llvm-dev]

Hello Min,

This error message occurs when the linker would have to create a
dynamic relocation in a read-only part of the program, which isn't
usually allowed when making a position independent shared-library or
position independent executable. In practice this usually means that
one or more of the objects hasn't been compiled to be position
independent -fPIC.

It is difficult to tell much more without knowing the compiler and
linker options. The R_AARCH64_PREL64 relocation is a relative
relocation, this can require a dynamic relocation if the symbol it
refers to is preemptible (i.e another definition of the symbol could
potentially override it at load-time).

Given that the file sha1-armv8.S is an assembler file, and I assume
that the link with the same inputs works on ld.bfd and ld.gold, I can
only think that it will either be lld is selecting a different object,
or ld.bfd and ld.gold are resolving the R_AARCH64_PREL64 relocation in
this case and lld is not.

Peter

On 23 March 2017 at 04:29, Minseong Kim via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> It would be great if anyone can share your thoughts about the cause and
> possibly fix of the error below ?
>
> I would like to know why it is caused and how it can be fixed (if possible)
> ?
>
> The error message is:
>
> ~/llvm/build/install_android/linux-x86/clang-3688880/bin/ld.lld: error:
> external/boringssl/linux-aarch64/crypto/sha/sha1-armv8.S:1202: can't create
> dynamic relocation R_AARCH64_PREL64 against symbol 'OPENSSL_armcap_P'
> defined in
> out/target/product/hikey/obj/STATIC_LIBRARIES/libcrypto_intermediates/libcrypto.a(sha1-armv8.o)
> clang-5.0: error: linker command failed with exit code 1 (use -v to see
> invocation)
>
> cheers,
> -- Min
>
>
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