qemu-ubuntu-arm64 kernel

安装qemu

sudo apt install qemu-system-arm

安装编译调试工具

sudo apt install gcc-aarch64-linux-gnu
sudo apt install libncurses5-dev
sudo apt install gdb-multiarch

下载&编译Busybox

# busybox官网
https://busybox.net/

# Settings  --->
# [*] Build static binary (no shared libs)
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j8
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- install

下载&编译kernel

# 下载网址
http://ftp.sjtu.edu.cn/sites/ftp.kernel.org/pub/linux/kernel/

# General setup  --->
#   [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
# Device Drivers  --->
#   [*] Block devices  --->
#     <*>   RAM block device support
# File systems  --->
#   <*> The Extended 4 (ext4) filesystem
make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 menuconfig
make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 -j8 Image

make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 defconfig

Image在目录“arch/arm64/boot”

制作rootfs

cd busybox
mkdir _install/proc _install/sys _install/dev _install/etc _install/etc/init.d
cat > _install/etc/init.d/rcS << EOF
#!/bin/sh
mount -t proc none /proc
mount -t sysfs none /sys
/sbin/mdev -s
[ ! -h /etc/mtab ]  && ln -s /proc/mounts /etc/mtab
[ ! -f /etc/resolv.conf ] && cat /proc/net/pnp > /etc/resolv.conf
EOF
chmod +x _install/etc/init.d/rcS


mkdir _rootfs
rsync -a busybox/_install/ _rootfs
sudo chown -R root:root _rootfs
cd _rootfs
find . | cpio -o --format=newc > ../rootfs.cpio
cd ..
gzip -c rootfs.cpio > rootfs.cpio.gz

执行qemu

qemu-system-aarch64  \
    -nographic \
    -no-reboot \
    -machine virt \
    -cpu cortex-a57 \
    -smp 2 -m 256 \
    -kernel Image \
    -initrd rootfs.cpio.gz \
    -append "panic=5 ro ip=dhcp root=/dev/ram rdinit=/sbin/init loglevel=8"

# 开启调试
qemu-system-aarch64  \
    -nographic \
    -no-reboot \
    -machine virt \
    -cpu cortex-a57 \
    -smp 2 -m 256 \
    -kernel Image \
    -initrd rootfs.cpio.gz \
    -append "panic=5 ro ip=dhcp root=/dev/ram rdinit=/sbin/init loglevel=8" \
    -S -gdb tcp::9000

-nographic do not use graphics, and redirect serial I/O to console
-no-reboot exit instead of rebooting
-smp 核数目
-m 物理内存大小
-kernel 内核压缩镜像位置
-initrd rootfs位置
-append cmdline启动参数
-S 在入口处阻塞CPU
-gdb tcp::xxxx 指定通信通道为本地tcp，端口号为xxxx，如果不需要指定端口号可以用-s 代替

# 新开一个窗口启动gdb并链接
gdb-multiarch --tui vmlinux
（gdb）target remote :9000
（gdb）break start_kernel
（gdb）continue
（gdb）step

先按ctrl + a，再按x，可退出qemu

参考文档

• https://elinux.org/QEMU
• https://wiki.qemu.org/Documentation