liblkl_hijack.so vs liblkl-hijack.so?

[pscollins]

tools/lib/Makefile provides two targets with slightly different names:

ifneq (,$(filter $(OUTPUT_FORMAT),elf64-x86-64))
lib += lib/liblkl_hijack.so
hijack_objs = $(patsubst %.c,%.o,$(wildcard lib/hijack/*.c))
objs += $(hijack_objs)
endif


lib/liblkl_hijack.so: LDFLAGS += -ldl
lib/liblkl_hijack.so: $(hijack_objs) lib/liblkl.a
        $(CC) -o $@ -shared $^  $(LDFLAGS)

# order of -lxxx again really matters for LD_PRELOAD
lib/liblkl-hijack.so: $(hijack_objs) Makefile lib/liblkl.so
        $(CC) -shared -nodefaultlibs $(lib_objs) -Llib -llkl $(hijack_objs) \
        -ldl -lpthread -lrt -o $@

On my machine, I can't get liblkl_hijack.so to work:

➜  lib git:(debug) ✗ LD_LIBRARY_PATH=. LD_PRELOAD=liblkl_hijack.so ping localhost
ERROR: ld.so: object 'liblkl_hijack.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.

The rules for liblkl_hijack.so don't make sense to me --- why would the hijacking code need to be linked against lkl on some architectures but not others? --- but if they're correct then the conditional should be rewritten to ifeq (elf64-x86-64,$(OUTPUT_FORMAT)) and the _ version should get a more descriptive name.

My suspicion is that this is a bad copy+paste or something like that --- is there a reason for it that I'm missing?

[thehajime]

I think it's accidentally injected during PR/review/merge processes of the original patch.

Originally it was liblkl-hijack.so is the right target as specified in tools/lkl/bin/lkl-hijack.sh, so I think liblkl_hijack.so is not intended to be used.

@tavip, let me know if you have any opinion to remove liblkl_hijack.so is fine or not.

but if they're correct then the conditional should be rewritten to ifeq (elf64-x86-64,$(OUTPUT_FORMAT)) and the _ version should get a more descriptive name.

I don't understand what you meant by _the version_. It'd be nice if you elaborate on this more.

I think it's accidentally injected during PR/review/merge processes of the original patch.

Originally it was liblkl-hijack.so is the right target as specified in tools/lkl/bin/lkl-hijack.sh, so I think liblkl_hijack.so is not intended to be used.

@tavip, let me know if you have any opinion to remove liblkl_hijack.so is fine or not.

Yeah, I messed it up, sorry about that :( We should remove liblkl_hijack.so.

[pscollins]

@thehajime I meant "the version containing a _ character, lib_hijack.so." It's all cleared up now, though!

[thehajime]

@pscollins got the point. thanks for the clarification.