【工程師分享】MPSoC交叉編譯例子

有工程師反饋,使用A53交叉編譯器直接編譯最簡單的C文件,編譯器也報告。"stdio.h: No such file or directory"

aarch64-xilinx-linux-gcc -c hello.c -DPLATFORM_ZCU106 -std=c11 -o hello.o
hello.c:3:10: fatal error: stdio.h: No such file or directory
 #include <stdio.h>

GCC編譯代碼時,缺省是在目錄/usr/include查找頭文件,在目錄/usr/lib查找?guī)煳募Ｈ绻墙徊婢幾g,就不能在主機的目錄下查找頭文件和庫文件,因為它們包含的是主機的應(yīng)用程序的文件。我們需要指定目標(biāo)單板的頭文件和庫文件。對于這種需求，GCC使用選項sysroot來實現(xiàn)。

GCC文檔關(guān)于sysroot的描述如下：

--sysroot=dir
Use dir as the logical root directory for headers and libraries. For example, 
if the compiler normally searches for headers in /usr/include and libraries 
in /usr/lib, it instead searches dir/usr/include and dir/usr/lib.

If you use both this option and the -isysroot option, then the --sysroot option 
applies to libraries, but the -isysroot option applies to header files.

The GNU linker (beginning with version 2.16) has the necessary support for this 
option. If your linker does not support this option, the header file aspect of 
--sysroot still works, but the library aspect does not.

GCC文檔關(guān)于sysroot的描述：

https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html

使用sysroot指定目錄后，編譯文件成功，沒有任何問題。

aarch64-xilinx-linux-gcc --sysroot=/opt/petalinux/2019.2/sysroots/aarch64-xilinx-linux -c hello.c     -DPLATFORM_ZCU106 -std=c11 -o hello.o
aarch64-xilinx-linux-gcc --sysroot=/opt/petalinux/2019.2/sysroots/aarch64-xilinx-linux -o hello hello.o -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed `pkg-config --cflags --libs glib-2.0 gstreamer-1.0 gstreamer-app-1.0` -lpthread -ldl -lrt -Wl,-rpath-link, -Wl,-O1 -Wl,--hash-style=gnu -Wl,--allow-multiple-definition

在命令行下指定sysroot目錄，只能適用于非常簡單的代碼。對于應(yīng)用程序的開發(fā)，建議使用Makefile。下面提供一個Makefile的例子。

#source "$dir_build/environment-setup-aarch64-xilinx-linux"

PLNX_AARCH_PATH=/opt/petalinux/2019.2/sysroots/aarch64-xilinx-linux

WARNING_CFLAGS =  -Wall 

CC = aarch64-xilinx-linux-gcc --sysroot=$(PLNX_AARCH_PATH)

export PKG_CONFIG_PATH=$(PLNX_AARCH_PATH)/usr/lib/pkgconfig/
LDFLAGS += -lpthread -ldl -lrt -Wl,-rpath-link, -Wl,-O1 -Wl,--hash-style=gnu 

SOURCES = $(wildcard *.c)
OBJECTS = $(patsubst %.c,%.o,$(SOURCES))

CFLAGS = -DPLATFORM_ZCU106 -std=c11

all: hello

hello: hello.o
	$(CC) -o $@ hello.o $(LDFLAGS)

%.o: %.c
	$(CC) -c $< $(CFLAGS) -o $@

clean:
	rm -f $(wildcard *.o) hello

在petalinux工程中，執(zhí)行petalinux-build –sdk，編譯完成后能得到sdk.sh。
安裝sdk.sh，后得到文件environment-setup-aarch64-xilinx-linux。執(zhí)行source environment-setup-aarch64-xilinx-linux，配置好交叉編譯器的路徑。
在Makefile里，設(shè)置sysroot為其中的sysroots/aarch64-xilinx-linux/,GCC就能找到正確的頭文件和庫文件。

hankf@xszgs4:/opt/petalinux/2019.2$ ls -l
total 28
-rw-r--r-- 1 root root  3502 Jan 17  2020 environment-setup-aarch64-xilinx-linux
-rw-r--r-- 1 root root 13970 Jan 17  2020 site-config-aarch64-xilinx-linux
drwxr-xr-x 4 root root  4096 Oct  5  2019 sysroots
-rw-r--r-- 1 root root    96 Jan 17  2020 version-aarch64-xilinx-linux
hankf@xszgs4:/opt/petalinux/2019.2$ ls -l sysroots/aarch64-xilinx-linux/
total 60
drwxr-xr-x  3 xilinx root 4096 Jan 13  2020 bin
drwxr-xr-x  2 xilinx root 4096 Jan 13  2020 boot
drwxr-xr-x  2 xilinx root 4096 Jan 13  2020 dev
drwxr-xr-x 46 xilinx root 4096 Jan 13  2020 etc
drwxr-xr-x  3 xilinx root 4096 Jan 13  2020 home
drwxr-xr-x  9 xilinx root 4096 Oct  5  2019 lib
drwxr-xr-x  2 xilinx root 4096 Jan 13  2020 media
drwxr-xr-x  2 xilinx root 4096 Jan 13  2020 mnt
dr-xr-xr-x  2 xilinx root 4096 Jan 13  2020 proc
drwxr-xr-x  2 xilinx root 4096 Jan 13  2020 run
drwxr-xr-x  3 xilinx root 4096 Jan 13  2020 sbin
dr-xr-xr-x  2 xilinx root 4096 Jan 13  2020 sys
drwxrwxrwt  2 xilinx root 4096 Jan 13  2020 tmp
drwxr-xr-x 10 xilinx root 4096 Oct  5  2019 usr
drwxr-xr-x  9 xilinx root 4096 Oct  5  2019 var
hankf@xszgs4:/opt/petalinux/2019.2$ source environment-setup-aarch64-xilinx-linux 
hankf@xszgs4:/opt/petalinux/2019.2$ aarch64-xilinx-linux-gcc --version
aarch64-xilinx-linux-gcc (GCC) 8.2.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
hankf@xszgs4:/opt/petalinux/2019.2$ which aarch64-xilinx-linux-gcc
/opt/petalinux/2019.2/sysroots/x86_64-petalinux-linux/usr/bin/aarch64-xilinx-linux/aarch64-xilinx-linux-gcc