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    Subject[PATCH v2 0/5] -ffreestanding/-fno-builtin-* patches
    From
    A recent "libcall optimization" addition to LLVM will emit libcalls to
    stpcpy, which the kernel doesn't provide an implementation, breaking
    almost all kernel builds with ToT Clang. Disable it for clang.

    We discussed providing an implementation, but the interface is generally
    unsafe as it provides no bounds checking.

    -fno-builtin-foo doesn't prevent GCC from emitting calls to foo, and GCC
    doesn't currently do the same libcall optimizations. If it ever does,
    then we can resurrect these implementations, but right now, YAGNI. So we
    only add these flags to CLANG_FLAGS to solve a Clang specific issue.

    The first patch is critical, I'm hoping Masahiro will pick it for the
    Kbuild tree and help us to get the fix in 5.9.

    The rest are cleanups; sending them for feedback/review/testing. Once
    the first hits mainline, I plan to resend the rest to the x86
    maintainers for inclusion in tip.

    Nick Desaulniers (5):
    Makefile: add -fno-builtin-stpcpy
    Makefile: add -fno-builtin-bcmp
    Revert "lib/string.c: implement a basic bcmp"
    x86/boot: use -fno-builtin-bcmp
    x86: don't build CONFIG_X86_32 as -ffreestanding

    Makefile | 2 ++
    arch/x86/Makefile | 3 ---
    arch/x86/boot/Makefile | 1 +
    arch/x86/boot/string.c | 8 --------
    include/linux/string.h | 3 ---
    lib/string.c | 20 --------------------
    6 files changed, 3 insertions(+), 34 deletions(-)

    --
    2.28.0.297.g1956fa8f8d-goog

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