How to compile DPDK application such as examples to support C++? - c++

Question

How should I modify Makefiles of DPDK to support c++ compilation? I tried by adding CFLAGS += -lstdc++ to the Makefile of the helloworld example but it seems not working. Is there a more standard way to do that?
Edited:
I'm using the makefile of helloworld example in DPDK 20.08 with some small modifications. I'm building it on ubuntu 20.04 ,and which is not cross-compilation. The DPDK is built with dpdk-setup script and not meson. The makefile is
# SPDX-License-Identifier: BSD-3-Clause
# Copyright(c) 2010-2014 Intel Corporation
# binary name
APP = rss_helper
# all source are stored in SRCS-y
# SRCS-y := main.c
SRCS-y := test.cpp
# Build using pkg-config variables if possible
ifeq ($(shell pkg-config --exists libdpdk && echo 0),0)
all: shared
# all: static
.PHONY: shared static
shared: build/$(APP)-shared
ln -sf $(APP)-shared build/$(APP)
static: build/$(APP)-static
ln -sf $(APP)-static build/$(APP)
PKGCONF ?= pkg-config
PC_FILE := $(shell $(PKGCONF) --path libdpdk 2>/dev/null)
CFLAGS += -O3 $(shell $(PKGCONF) --cflags libdpdk)
LDFLAGS_SHARED = $(shell $(PKGCONF) --libs libdpdk)
LDFLAGS_STATIC = $(shell $(PKGCONF) --static --libs libdpdk)
build/$(APP)-shared: $(SRCS-y) Makefile $(PC_FILE) | build
$(CC) $(CFLAGS) $(SRCS-y) -o $# $(LDFLAGS) $(LDFLAGS_SHARED)
build/$(APP)-static: $(SRCS-y) Makefile $(PC_FILE) | build
$(CC) $(CFLAGS) $(SRCS-y) -o $# $(LDFLAGS) $(LDFLAGS_STATIC)
build:
#mkdir -p $#
.PHONY: clean
clean:
rm -f build/$(APP) build/$(APP)-static build/$(APP)-shared
test -d build && rmdir -p build || true
else
ifeq ($(RTE_SDK),)
$(error "Please define RTE_SDK environment variable")
endif
# Default target, detect a build directory, by looking for a path with a .config
RTE_TARGET ?= $(notdir $(abspath $(dir $(firstword $(wildcard $(RTE_SDK)/*/.config)))))
include $(RTE_SDK)/mk/rte.vars.mk
CPPFLAGS += -O3
CPPFLAGS += $(WERROR_FLAGS)
CPPFLAGS += -DALLOW_EXPERIMENTAL_API
CPPFLAGS += -lstdc++
include $(RTE_SDK)/mk/rte.extapp.mk
endif
I changed the name of the source file and flags. The source file test.cpp contains only iostream header and an empty main function (just for test). There are two errors:
can't find the test.cpp with cpp on. It works find when replace test.cpp in makefile with test.c while keeping the actual source file name as test.cpp.
LD rss_helper
gcc: error: test.cpp: No such file or directory
make[1]: *** [/home/syk/dpdk-20.08/mk/rte.app.mk:456: rss_helper] Error 1
make: *** [/home/syk/dpdk-20.08/mk/rte.extapp.mk:15: all] Error 2
Error for LD like below
g++ -O3 -W -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wold-style-definition -Wpointer-arith -Wcast-align -Wnested-externs -Wcast-qual -Wformat-nonliteral -Wformat-security -Wundef -Wwrite-strings -Wdeprecated -Wno-missing-field-initializers -Wimplicit-fallthrough=2 -Wno-format-truncation -Wno-address-of-packed-member -DALLOW_EXPERIMENTAL_API -lstdc++ -c -o test.o /home/syk/loadbalancing/rss_helper_demo/test.cpp
cc1plus: warning: command line option ‘-Wstrict-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command line option ‘-Wmissing-prototypes’ is valid for C/ObjC but not for C++
cc1plus: warning: command line option ‘-Wold-style-definition’ is valid for C/ObjC but not for C++
cc1plus: warning: command line option ‘-Wnested-externs’ is valid for C/ObjC but not for C++
LD rss_helper
/usr/bin/ld: test.o: in function `_GLOBAL__sub_I_main':
test.cpp:(.text.startup+0x20): undefined reference to `std::ios_base::Init::Init()'
/usr/bin/ld: test.cpp:(.text.startup+0x27): undefined reference to `std::ios_base::Init::~Init()'
collect2: error: ld returned 1 exit status
make[1]: *** [/home/syk/dpdk-20.08/mk/rte.app.mk:456: rss_helper] Error 1
make: *** [/home/syk/dpdk-20.08/mk/rte.extapp.mk:15: all] Error 2
I tried to resolve it by added -lstdc++ but still had it.
Edited-2：
The source file:
#include <iostream>
#include <rte_eal.h>
using namespace std;
class A{
int a;
};
int
main(void){
return 0;
}
It can't include iostream and rte_eal either.

Answer 1

there are 2 possible ways to solve this issue
set environment set CC=g++. Then execute make
edit Makefile to add CC = g++
with these changes I am able build and run the sample code.
linux-vdso.so.1 (0x00007fff0a3e6000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f1389440000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f138904f000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f1388cb1000)
/lib64/ld-linux-x86-64.so.2 (0x00007f13899cb000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f1388a99000)
and
ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=6e3fb6ed5f48b8f66fe4c05118f7b6bf6a9a1235, not stripped

Answer 2

You need to modify the makefile inorder to adapt C++:
You need to change CFLAGS to CPPFLAGS
See below reference example:
ifeq ($(RTE_SDK),)
$(error "Please define RTE_SDK environment variable")
endif
# Default target, can be overriden by command line or environment
RTE_TARGET ?= x86_64-native-linuxapp-gcc
include $(RTE_SDK)/mk/rte.vars.mk
# binary name
APP = dpdkrecv
# all source are stored in SRCS-y
SRCS-y := main.c syncshm.c cqf.cpp countingquotientfilter.cpp murmurhash3.cpp
CPPFLAGS += -O3 -mbmi2
CFLAGS += $(WERROR_FLAGS)
include $(RTE_SDK)/mk/rte.extapp.mk

Answer 3

Please share the Makefile,
I am adding
#include algorithm
dpdk ver: dpdk-stable-18.11.2 ,
build with
sudo make install T=x86_64-native-linuxapp-gcc DESTDIR=install