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Diffstat (limited to 'tools/testing/selftests/bpf/README.rst')
| -rw-r--r-- | tools/testing/selftests/bpf/README.rst | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst index 3353778c30f8..8deec1ca9150 100644 --- a/tools/testing/selftests/bpf/README.rst +++ b/tools/testing/selftests/bpf/README.rst @@ -202,3 +202,22 @@ generate valid BTF information for weak variables. Please make sure you use Clang that contains the fix. __ https://reviews.llvm.org/D100362 + +Clang relocation changes +======================== + +Clang 13 patch `clang reloc patch`_ made some changes on relocations such +that existing relocation types are broken into more types and +each new type corresponds to only one way to resolve relocation. +See `kernel llvm reloc`_ for more explanation and some examples. +Using clang 13 to compile old libbpf which has static linker support, +there will be a compilation failure:: + + libbpf: ELF relo #0 in section #6 has unexpected type 2 in .../bpf_tcp_nogpl.o + +Here, ``type 2`` refers to new relocation type ``R_BPF_64_ABS64``. +To fix this issue, user newer libbpf. + +.. Links +.. _clang reloc patch: https://reviews.llvm.org/D102712 +.. _kernel llvm reloc: /Documentation/bpf/llvm_reloc.rst |