使用qemu搭建ARM64调试环境,支持文件共享,支持gdb调试

环境

主机ubuntu版本: 20.04
qemu模拟处理器:ARM64
Linux内核版本:https://www.kernel.org/ 最新版

step1:安装编译工具链

sudo apt-get install gcc-aarch64-linux-gnu
sudo apt-get install libncurses5-dev  build-essential git bison flex libssl-dev

查看版本号

leon@leon:~/work$ aarch64-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=aarch64-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc-cross/aarch64-linux-gnu/9/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 9.3.0-10ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,gm2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-9 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --without-target-system-zlib --enable-libpth-m2 --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=aarch64-linux-gnu --program-prefix=aarch64-linux-gnu- --includedir=/usr/aarch64-linux-gnu/include
Thread model: posix
gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu1) 

step2:安装qemu

sudo apt-get install qemu-system-arm

查看版本:

leon@leon:~/work$ qemu-system-aarch64 --version
QEMU emulator version 4.2.1 (Debian 1:4.2-3ubuntu6.16)
Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
leon@leon:~/work$ 

step3:制作根文件系统rootfs

3.1 下载busybox源码:

官网:http://busybox.net/downloads/
下载最新版本即可,这里

tar jxvf busybox-1.33.1.tar.bz2 

3.2 配置busybox

指定编译工具

export ARCH=arm64
export CROSS_COMPILE=aarch64-linux-gnu-

打开静态库编译选项

make menuconfig
Settings --->
 [*] Build static binary (no shared libs)   

如果报错:

<command-line>: fatal error: curses.h: No such file or directory
compilation terminated.

安装ncurses库

sudo apt-get install libncurses5-dev libncursesw5-dev

3.3 编译

make
make install

PS:编译过程报错的话,把相应项去掉即可;

编译完成,在busybox生成_install目录

3.4 补充rootfs目录结构

(1) 根目录添加etc、dev和lib目录

etc目录:

leon@leon:~/work/Linux/busybox-1.33.1/_install$ ls
bin  linuxrc  sbin  usr
leon@leon:~/work/Linux/busybox-1.33.1/_install$ mkdir etc dev lib
leon@leon:~/work/Linux/busybox-1.33.1/_install$ ls
bin  dev  etc  lib  linuxrc  sbin  usr
leon@leon:~/work/Linux/busybox-1.33.1/_install$ 

在etc分别创建文件:

leon@leon:~/work/Linux/busybox-1.33.1/_install/etc$ cat profile 
#!/bin/sh
export HOSTNAME=myQEMU
export USER=root
export HOME=/home
export PS1="[$USER@$HOSTNAME \W]\# "
PATH=/bin:/sbin:/usr/bin:/usr/sbin
LD_LIBRARY_PATH=/lib:/usr/lib:$LD_LIBRARY_PATH
export PATH LD_LIBRARY_PATH
leon@leon:~/work/Linux/busybox-1.33.1/_install/etc$ cat fstab 
#device  mount-point    type     options   dump   fsck order
proc /proc proc defaults 0 0
tmpfs /tmp tmpfs defaults 0 0
sysfs /sys sysfs defaults 0 0
tmpfs /dev tmpfs defaults 0 0
debugfs /sys/kernel/debug debugfs defaults 0 0
kmod_mount /mnt 9p trans=virtio 0 0
leon@leon:~/work/Linux/busybox-1.33.1/_install/etc$ cat inittab 
::sysinit:/etc/init.d/rcS
::respawn:-/bin/sh
::askfirst:-/bin/sh
::ctrlaltdel:/bin/umount -a -r

指定挂载的文件系统

leon@leon:~/work/Linux/busybox-1.33.1/_install/etc/init.d$ cat rcS 
mkdir -p /sys
mkdir -p /tmp
mkdir -p /proc
mkdir -p /mnt
/bin/mount -a
mkdir -p /dev/pts
mount -t devpts devpts /dev/pts
echo /sbin/mdev > /proc/sys/kernel/hotplug
mdev -s
leon@leon:~/work/Linux/busybox-1.33.1/_install/etc/init.d$ 

dev目录:

leon@leon:~/work/Linux/busybox-1.33.1/_install/dev$ sudo mknod console c 5 1
leon@leon:~/work/Linux/busybox-1.33.1/_install/dev$ sudo mknod null c 1 3
leon@leon:~/work/Linux/busybox-1.33.1/_install/dev$ 

lib目录:拷贝lib库,支持动态编译的应用程序运行

leon@leon:~/work/Linux/busybox-1.33.1/_install/lib$ cp /usr/aarch64-linux-gnu/lib/*.so*  -a .
leon@leon:~/work/Linux/busybox-1.33.1/_install/lib$ ls
ld-2.31.so               libdl-2.31.so     libnsl.so              libnss_nisplus-2.31.so  libSegFault.so
ld-linux-aarch64.so.1    libdl.so          libnsl.so.1            libnss_nisplus.so       libstdc++.so.6
libanl-2.31.so           libdl.so.2        libnss_compat-2.31.so  libnss_nisplus.so.2     libstdc++.so.6.0.28
libanl.so                libgcc_s.so.1     libnss_compat.so       libnss_nis.so           libthread_db-1.0.so
libanl.so.1              libgomp.so.1      libnss_compat.so.2     libnss_nis.so.2         libthread_db.so
libasan.so.5             libgomp.so.1.0.0  libnss_dns-2.31.so     libpcprofile.so         libthread_db.so.1
libasan.so.5.0.0         libitm.so.1       libnss_dns.so          libpthread-2.31.so      libtsan.so.0
libatomic.so.1           libitm.so.1.0.0   libnss_dns.so.2        libpthread.so           libtsan.so.0.0.0
libatomic.so.1.2.0       liblsan.so.0      libnss_files-2.31.so   libpthread.so.0         libubsan.so.1
libBrokenLocale-2.31.so  liblsan.so.0.0.0  libnss_files.so        libresolv-2.31.so       libubsan.so.1.0.0
libBrokenLocale.so       libm-2.31.so      libnss_files.so.2      libresolv.so            libutil-2.31.so
libBrokenLocale.so.1     libmemusage.so    libnss_hesiod-2.31.so  libresolv.so.2          libutil.so
libc-2.31.so             libm.so           libnss_hesiod.so       librt-2.31.so           libutil.so.1
libc.so                  libm.so.6         libnss_hesiod.so.2     librt.so
libc.so.6                libnsl-2.31.so    libnss_nis-2.31.so     librt.so.1
leon@leon:~/work/Linux/busybox-1.33.1/_install/lib$ 

step4 编译内核

(1)下载代码:

#我从torvalds的仓库fork了一个分支,方便自己添加注释笔记
git clone https://github.com/luteresa/linux.git  

(2) 指定编译工具:

export ARCH=arm64
export CROSS_COMPILE=aarch64-linux-gnu-

配置内核:
这里采用ARM公司提供的Versatile Express开发平台模拟;

sudo cp ../busybox-1.33.1/_install/  ./_install_arm64 -a
cp arch/arm/configs/vexpress_defconfig  .config
make menuconfig

添加hotplug支持:

 Device Drivers                                                                                             	
 	-> Generic Driver Options                                                                                   			 
 		-> Support for uevent helper                                                                                                                
			(/sbin/hotplug) path to uevent helper

添加initramfs的支持:

General setup --->
	[*]Initial RAM filesystem and RAM disk(initramfs/initrd) support(_install_arm64) Initramfs souce file(s)

内核页分别配置为

Kernel Features  --->
	Page size(4KB)  --->
	Virtual address space size(48-bit)--->

编译:

make all -j8

在内核根目录下添加共享目录

mkdir kmodules

启动Linux:

qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine type=virt -m 1024 -smp 4 -kernel arch/arm64/boot/Image --append "rdinit=/linuxrc root=/dev/vda rw console=ttyAMA0 loglevel=8"  -nographic --fsdev local,id=kmod_dev,path=$PWD/kmodules,security_model=none -device virtio-9p-device,fsdev=kmod_dev,mount_tag=kmod_mount

-cpu指定模拟的cpu为 cortex-a57,
-m 1024 指定内存大小为1G,
-smp4指定模拟的系统为4核处理器 ,
-kernel指定启动的内核镜像,
–append指定传递的命令行参数,
后面的选项指定共享目录已经使用的9P协议。

报错:

mount: mounting debugfs on /sys/kernel/debug failed: No such file or directory

内核配置加上CONFIG_DEBUG_FS=y :

 Kernel hacking  ---> 
 	 Generic Kernel Debugging Instruments  --->  
 	 	 [*] Debug Filesystem   

step5: 使用模拟磁盘

上述initramfs的方式,将根文件系统打包到内核源码,运行时都是在内存中,可以操作,但系统重启就会丢失,下面用模拟磁盘方式挂载根文件系统。
制作磁盘文件:

dd if=/dev/zero of=rootfs_ext4.img bs=1M count=1024
mkfs.ext4 rootfs_ext4.img
mkdir -p tmpfs
sudo mount  -t ext4 rootfs_ext4.img  tmpfs/ -o loop
sudo cp -af _install_arm64/* tmpfs/
sudo umount  tmpfs
chmod 777 rootfs_ext4.img

rootfs_ext4.img就是即将用来挂载的磁盘;
再次启动内核:

qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine type=virt -m 1024 -smp 4 -kernel arch/arm64/boot/Image --append "noinitrd root=/dev/vda rw console=ttyAMA0 loglevel=8"  -nographic -drive if=none,file=rootfs_ext4.img,id=hd0 -device virtio-blk-device,drive=hd0 --fsdev local,id=kmod_dev,path=$PWD/kmodules,security_model=none -device virtio-9p-device,fsdev=kmod_dev,mount_tag=kmod_mount

传递给内核的命令行参数变化了,添加了noinitrd选项,这样就会挂载我们自己的模拟磁盘。

[root@myQEMU ]# df -mh
Filesystem                Size      Used Available Use% Mounted on
/dev/root               975.9M     12.8M    895.9M   1% /
tmpfs                   496.1M         0    496.1M   0% /tmp
tmpfs                   496.1M         0    496.1M   0% /dev
kmod_mount              981.8G     32.5G    899.4G   3% /mnt
[root@myQEMU ]# 

这样在文件系统的读写,就会存在磁盘,重启后,数据不会丢失。

step6: qemu与主机ubuntu文件共享

前面已经支持了主机和qemu上的系统共享目录,这个目录就是kmodules目录:
通过mount可以查看被挂载到了qemu上的系统的/mnt目录下

[root@myQEMU mnt]# mount
/dev/root on / type ext4 (rw,relatime)
proc on /proc type proc (rw,relatime)
tmpfs on /tmp type tmpfs (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
tmpfs on /dev type tmpfs (rw,relatime)
kmod_mount on /mnt type 9p (rw,sync,dirsync,relatime,access=client,trans=virtio)
devpts on /dev/pts type devpts (rw,relatime,mode=600,ptmxmode=000)

在ubuntu的kmodules目录,创建一个文件hello.c

#include 

int main(int argc, char **argv)
{
        printf("Hello World,Qemu!\n");

        return 0;
}

在qemu查看

[root@myQEMU mnt]# cat /proc/cpuinfo  > cpu.txt
[root@myQEMU mnt]# cat hello.c
#include 
int main(int argc, char **argv)
{ 
        printf("Hello World,Qemu!\n"); 
        return 0; 
}
random: fast init done
[root@myQEMU mnt]# 

在ubuntu编译,

aarch64-linux-gnu-gcc  hello.c

在qemu运行,

[root@myQEMU mnt]# ./a.out 
Hello World,Qemu!
[root@myQEMU mnt]# 

可见,在共享目录,可以执行含动态库的应用程序;

step7:内核模块测试:

Makefile文件,

KERNEL_DIR ?= ~/work/Linux/linux
obj-m := module_test.o
modules:
	$(MAKE) -C $(KERNEL_DIR) M=$(PWD) modules
clean: 
	$(MAKE) -C $(KERNEL_DIR) M=$(PWD) clean
install:         
	cp *.ko $(KERNEL_DIR)/kmodules

驱动测试文件model_test.c,

#include 
#include 
#include 
   static int __init module_test_init(void)
{
        printk("---module_test_init\n");
        return 0;
}    
  
  static void __exit module_test_exit(void)
{
        printk("---module_test_exit\n");
}
  
  
module_init(module_test_init);
module_exit(module_test_exit);
MODULE_LICENSE("GPL");

在ubuntu上交叉编译

leon@leon:~/work/Linux/linux/kmodules$ make
make -C ~/work/Linux/linux M=/home/leon/work/Linux/linux/kmodules modules
make[1]: Entering directory '/home/leon/work/Linux/linux'
  CC [M]  /home/leon/work/Linux/linux/kmodules/module_test.o
  MODPOST /home/leon/work/Linux/linux/kmodules/Module.symvers
  CC [M]  /home/leon/work/Linux/linux/kmodules/module_test.mod.o
  LD [M]  /home/leon/work/Linux/linux/kmodules/module_test.ko
make[1]: Leaving directory '/home/leon/work/Linux/linux'
leon@leon:~/work/Linux/linux/kmodules$ 

在qemu加载驱动

[root@myQEMU mnt]# insmod module_test.ko 
---module_test_init.
[root@myQEMU mnt]# rmmod module_test
---module_test_exit.
[root@myQEMU mnt]# 

可见,内核模块正常运行了。

step8:gdb调试

安装arm-none-eabi-gdb
https://askubuntu.com/questions/1243252/how-to-install-arm-none-eabi-gdb-on-ubuntu-20-04-lts-focal-fossa

sudo apt-get install gdb-multiarch

qemu模拟端启动内核:

qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine type=virt -m 1024 -smp 4 -kernel arch/arm64/boot/Image --append "rdinit=/linuxrc root=/dev/vda rw console=ttyAMA0 loglevel=8"  -nographic --fsdev local,id=kmod_dev,path=$PWD/k_shared,security_model=none -device virtio-9p-device,fsdev=kmod_dev,mount_tag=kmod_mount  -S  -s

X86启动gdb:

$ gdb-multiarch --tui vmlinux
(gdb)target remote localhost:1234  //通过1234端口远程连接到qemu端
(gdb)b start_kernel				   //在内核的start_kernel设置断点
(gdb)c

如图,gdb接管linux内核,在断点处(start_kernel)暂停,即可通过gdb来调试内核。
使用qemu搭建ARM64调试环境,支持文件共享,支持gdb调试_第1张图片
用Eclipse可视化环境,单步调试Linux内核,参考:
https://blog.csdn.net/luteresa/article/details/119188792

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