mold

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getting the following message when I try using it mold: fatal: unknown command line option: --cref currently this got it due to me building with RTE (DPDK) which enforces this flag

From ld man:

--cref
    Output a cross reference table. If a linker map file is being generated, the cross reference table is
    printed to the map file. Otherwise, it is printed on the standard output.
    The format of the table is intentionally simple, so that it may be easily processed by a script if
    necessary. The symbols are printed out, sorted by name. For each symbol, a list of file names is given. 
    if the symbol is defined, the first file listed is the location of the definition. The remaining files contain
    references to the symbol.

Is there some similar flag/feature I can enable if I want to use mold ?

We have --print-map, --print-dependencies and --print-dependencies=full options whose roles overlap with --cref, so I want to avoid implementing --cref. Can you give me a repository's URL at which I can see how --cref flag is being used in a real project?

@rui314 we are using an older version of DPDK, when you build an app for it - it will invoke this by default (to be completely honest, I'm not sure if we care too much for it for production cases - for now I removed it and seem ok-ish) see: https://github.com/DPDK/dpdk/blob/v20.08/mk/rte.app.mk#L403 I would of course prefer to use the code unmodified, but seeing as newer DPDK comes with meson.build and without this flag, you can probably ignore this feature request as they stopped using it in newer versions

EDIT: as a side-note, I do seem to encounter some problems with these applications now that I link with mold - but I'll run some tests and see if they relate/not to this flag (I really hope not) and/or changes to cache due to changing linker

I don't know why they added --cref in their Makefile, but it may be for "just in case". It looks like the file isn't used by other parts of the Makefile.

Feel free to file a new bug for the new issue. We are happy to investigate.

I don't know why they added --cref in their Makefile, but it may be for "just in case". It looks like the file isn't used by other parts of the Makefile.

Feel free to file a new bug for the new issue. We are happy to investigate.

It's not used in their Makefile because this is meant for application you compile yourself with the RTE/DPDK "infra" usage is as such:

# Default target, can be overridden by command line or environment
RTE_TARGET ?= x86_64-native-linuxapp-gcc

include $(RTE_SDK)/mk/rte.vars.mk

# binary name
APP = my_app

RTE_OUTPUT = ${SRCDIR}/build/${RTE_TARGET}/
# DPDK calls itself from the makefile..
# We need to add the parameters in the second call, the first one doesn't apply.
ifneq ($(NOT_FIRST_CALL),)

SRCS-y += $(shell find ${SRCDIR} \( -name "*.c" -o -name "*.cpp" \) -printf "%f ")
VPATH += $(shell find ${SRCDIR} -type d)
INC += ${SRCDIR}

# App flags
CPPFLAGS += -I${SRCDIR} -std=c++11
CPPFLAGS += -I${RTE_SDK}/${RTE_TARGET}/include
CFLAGS += -I${SRCDIR} -Werror -Wno-format-nonliteral
LDFLAGS += -ld -lstdc++

# Change linker to MOdernLDinker (silent D), see https://github.com/rui314/mold
# TODO(devops): once GCC supports -fuse-ld=mold don't hack it by using GOLD as alias
LDFLAGS += -fuse-ld=gold

ifeq ("${DEBUG_MODE}", "1")
$(info Compiling app in debug mode!)
CFLAGS += -DEBUG_MODE
CFLAGS += -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined
# Using "-Og -ggdb3" resulted optimized out variables, which arent' optimized out using "-O0 -g"
CFLAGS += -O0 -g
#CFLAGS += -Og -ggdb3

# Flags for code-coverage.
CFLAGS += --coverage
LDFLAGS += -lgcov
else
$(info Compiling app in release mode!)
CFLAGS += -O3 -g
endif
$(info ========================================================)
endif

CFLAGS += -fPIC
CPPFLAGS += -fPIC

include $(RTE_SDK)/mk/rte.extapp.mk

Small update: after doing extensive tests, it seems that there is 0 difference in runtime. I'm closing ticket since it is (so-far) a useless feature 🙂