On 5/18/26 2:03 AM, James Clark wrote: > Documentation/kbuild/llvm.rst mentions that readelf is included in the > LLVM toolchain, but it's not currently included in this block. > > Add it so that LLVM=... options also apply to readelf. Users in tools/ > were Perf which was hardcoding it, and another was the BPF makefile. > Both already include Makefile.include so convert them to use the new > variable. > > It also didn't have the cross compile prefix, so either readelf didn't > mind opening cross binaries, or it wasn't working for cross builds.
I'm pretty sure it's the former. readelf/llvm-readelf are only used libbpf makefile to read ELF symbol tables, which should be arch-independent. We've been cross-compiling the kernel (and libbpf) on BPF CI for a long time. So the unprefixed readelf is already working, and adding the $(CROSS_COMPILE) prefix only adds a new requirement. I don't think this change in tools/lib/bpf/Makefile is a good idea, we could potentially break some environments. Even though hardcoded readelf doesn't look nice. > > Signed-off-by: James Clark <[email protected]> > --- > tools/lib/bpf/Makefile | 8 ++++---- > tools/perf/Makefile.perf | 1 - > tools/scripts/Makefile.include | 2 ++ > 3 files changed, 6 insertions(+), 5 deletions(-) > > diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile > index 168140f8e646..180dca9c57c8 100644 > --- a/tools/lib/bpf/Makefile > +++ b/tools/lib/bpf/Makefile > @@ -114,12 +114,12 @@ PC_FILE := $(addprefix $(OUTPUT),$(PC_FILE)) > > TAGS_PROG := $(if $(shell which etags 2>/dev/null),etags,ctags) > > -GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \ > +GLOBAL_SYM_COUNT = $(shell $(READELF) -s --wide $(BPF_IN_SHARED) | \ > cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \ > sed 's/\[.*\]//' | \ > awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print > $$NF}' | \ > sort -u | wc -l) > -VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | > \ > +VERSIONED_SYM_COUNT = $(shell $(READELF) --dyn-syms --wide > $(OUTPUT)libbpf.so | \ > sed 's/\[.*\]//' | \ > awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print > $$NF}' | \ > grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u > | wc -l) > @@ -182,12 +182,12 @@ check_abi: $(OUTPUT)libbpf.so $(VERSION_SCRIPT) > "versioned symbols in $^ ($(VERSIONED_SYM_COUNT))." \ > "Please make sure all LIBBPF_API symbols are" \ > "versioned in $(VERSION_SCRIPT)." >&2; \ > - readelf -s --wide $(BPF_IN_SHARED) | \ > + $(READELF) -s --wide $(BPF_IN_SHARED) | \ > cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \ > sed 's/\[.*\]//' | \ > awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \ > sort -u > $(OUTPUT)libbpf_global_syms.tmp; \ > - readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \ > + $(READELF) --dyn-syms --wide $(OUTPUT)libbpf.so | > \ > sed 's/\[.*\]//' | \ > awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}'| \ > grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | \ > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > index 0aba14f22a06..63276bf55856 100644 > --- a/tools/perf/Makefile.perf > +++ b/tools/perf/Makefile.perf > @@ -215,7 +215,6 @@ FLEX ?= flex > BISON ?= bison > STRIP = strip > AWK = awk > -READELF ?= readelf > > # include Makefile.config by default and rule out > # non-config cases > diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include > index e81e5b479c56..380ad84ac51e 100644 > --- a/tools/scripts/Makefile.include > +++ b/tools/scripts/Makefile.include > @@ -73,6 +73,7 @@ ifneq ($(LLVM),) > $(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX)) > $(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX)) > $(call > allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX)) > + $(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX)) > else > # Allow setting various cross-compile vars or setting CROSS_COMPILE as a > prefix. > $(call allow-override,CC,$(CROSS_COMPILE)gcc) > @@ -80,6 +81,7 @@ else > $(call allow-override,LD,$(CROSS_COMPILE)ld) > $(call allow-override,CXX,$(CROSS_COMPILE)g++) > $(call allow-override,STRIP,$(CROSS_COMPILE)strip) > + $(call allow-override,READELF,$(CROSS_COMPILE)readelf) > > # Host versions aren't prefixed > $(call allow-override,HOSTAR,ar) >
