Re: [PATCH v3 06/11] selftests: Fix arm64 IO barriers to match kernel

[Nathan Chancellor <nathan@kernel.org>]

On Thu, Jul 16, 2026 at 02:03:22PM -0300, Jason Gunthorpe wrote:
> The tools/include readl/writel MMIO accessors on arm64 use
> inner-shareable barriers (dmb ish) while the kernel uses
> outer-shareable (dmb osh).  Fix them to match.
> 
> Add __io_bw() and __io_ar() definitions matching the kernel's
> arch/arm64/include/asm/io.h, including the dummy control dependency
> in __io_ar() that orders MMIO reads against all subsequent
> instructions.
> 
> Assisted-by: Claude:claude-opus-4.6
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
...
> diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk
> index f02cc8a2e4ae32..fdd22df9174b88 100644
> --- a/tools/testing/selftests/lib.mk
> +++ b/tools/testing/selftests/lib.mk
> @@ -5,9 +5,14 @@ ifneq ($(filter %/,$(LLVM)),)
>  LLVM_PREFIX := $(LLVM)
>  else ifneq ($(filter -%,$(LLVM)),)
>  LLVM_SUFFIX := $(LLVM)
> +else ifneq ($(LLVM),1)
> +$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
>  endif
>  
>  CLANG := $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
> +LD := $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
> +# Selftests link through $(CC), so point clang at the LLVM linker.
> +LDFLAGS += --ld-path=$(LD)
>  
>  CLANG_TARGET_FLAGS_arm          := arm-linux-gnueabi
>  CLANG_TARGET_FLAGS_arm64        := aarch64-linux-gnu

Was this hunk intended to be included in this change? It is not
mentioned anywhere. I assume this is the only reason that the LLVM folks
were CC'd on this series.

-- 
Cheers,
Nathan