On Thu, Jul 16, 2026 at 04:22:10PM -0700, Nathan Chancellor wrote:

On Thu, Jul 16, 2026 at 02:03:22PM -0300, Jason Gunthorpe wrote:

quoted

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>

...

quoted

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.

Er no, I can no longer remember what that was about, it wasn't in
v2. Actually I also see I forgot to delete this patch as Will
suggested in the first place.

Jason