如何编译支持C++的示例等DPDK应用？

Question

如何修改DPDK的Makefile来支持c++编译？我尝试将 CFLAGS += -lstdc++ 添加到 helloworld 示例的 Makefile 中，但它似乎不起作用。有更标准的方法吗？

已编辑：我在 DPDK 20.08 中使用 helloworld 示例的 makefile 并进行了一些小的修改。我在 ubuntu 20.04 上构建它，而不是 cross-compilation。 DPDK 是用 dpdk-setup 脚本而不是介子构建的。生成文件是

# 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

我更改了源文件的名称和标志。源文件 test.cpp 仅包含 iostream header 和一个空的主函数（仅用于测试）。有两个错误：

找不到启用了 cpp 的 test.cpp。它在将 makefile 中的 test.cpp 替换为 test.c 的同时保持实际源文件名为 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

如下 LD 的错误

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

我尝试通过添加 -lstdc++ 来解决它，但仍然存在。

编辑-2：源文件：

#include <iostream>
#include <rte_eal.h>
using namespace std;

class A{
    int a;
};

int
main(void){
    return 0;
}

它不能包括 iostream 和 rte_eal。

Answer 1

您需要修改 makefile 以适配 C++：
您需要将 CFLAGS 更改为 CPPFLAGS 请参阅下面的参考示例：

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 2

有 2 种可能的方法可以解决此问题

设置环境set CC=g++。然后执行make
编辑 Makefile 添加 CC = g++

通过这些更改，我可以构建运行示例代码。

        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)

和

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 3

请分享 Makefile，

我正在添加

#include algorithm

dpdk 版本：dpdk-stable-18.11.2，构建

sudo make install T=x86_64-native-linuxapp-gcc DESTDIR=install

如何编译支持C++的示例等DPDK应用？

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

c

c++

dpdk