QEMU启动ARM64 Linux内核
目录
前言
本文介绍采用 qemu 模拟ARM-64bit开发板(针对ARM-32bit的有另一篇文章介绍),并启动ARM64 Linux内核。大致思路是:
- 安装qemu-system-aarch64(ARM-64bit)模拟器;
- 安装aarch64-linux-gnu(ARM-64bit)交叉编译器;
- 交叉编译linux源码,得到ARM64 Linux内核镜像;
- 交叉编译busybox源码,使用busybox制作initramfs;
- 最后使用qemu-system-aarch64启用ARM64 Linux内核;
我的环境:
- 宿主机硬件平台:x86_64
- 宿主机操作系统:Ubuntu 20.04 (Linux 5.4.0-139-generic)
- QEMU版本:qemu-4.2.1
- 实验内核:linux-5.19
- busybox版本:busybox-1.35.0
前置知识
virt开发板
截至书稿本文时,QEMU模拟了多大70几种的硬件开发板,可参考Arm System emulator。但ARM-64bit的QEMU模拟器非常少,以至于virt成了唯一的选择。virt支持PCI,virtio,较新的ARM CPU,大容量内存,比较遗憾的是它不支持图形界面,如果你不知道选择什么硬件开发板就选virt。
更详尽的内容可参考:
Why the “virt”board?
Installing Debian on QEMU’s 32-bit ARM “virt”board
Installing Debian on QEMU’s 64-bit ARM “virt”board
ARM处理器家族简介
ARM处理器家族众多,哪些是32bit,哪些是64bit,可参考:
List_of_ARM_processors
很多厂家使用ARM核设计SOC芯片,这里罗列了很多,可参考:
List_of_products_using_ARM_processors
安装qemu-system-aarch64
安装:
$ sudo apt install qemu-system-arm
会同时安装ARM-32bit的qemu-system-arm版本和ARM-64bit的 qemu-system-aarch64版本,查看版本号:
$ qemu-system-aarch64 --version
QEMU emulator version 4.2.1 (Debian 1:4.2-3ubuntu6.24)
Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers
查看 qemu 支持的 ARM 内核开发板,本文选择virt开发板:
$ qemu-system-aarch64 -M help
Supported machines are:
akita Sharp SL-C1000 (Akita) PDA (PXA270)
ast2500-evb Aspeed AST2500 EVB (ARM1176)
ast2600-evb Aspeed AST2600 EVB (Cortex A7)
borzoi Sharp SL-C3100 (Borzoi) PDA (PXA270)
canon-a1100 Canon PowerShot A1100 IS
cheetah Palm Tungsten|E aka. Cheetah PDA (OMAP310)
collie Sharp SL-5500 (Collie) PDA (SA-1110)
connex Gumstix Connex (PXA255)
cubieboard cubietech cubieboard (Cortex-A8)
emcraft-sf2 SmartFusion2 SOM kit from Emcraft (M2S010)
highbank Calxeda Highbank (ECX-1000)
imx25-pdk ARM i.MX25 PDK board (ARM926)
integratorcp ARM Integrator/CP (ARM926EJ-S)
kzm ARM KZM Emulation Baseboard (ARM1136)
lm3s6965evb Stellaris LM3S6965EVB
lm3s811evb Stellaris LM3S811EVB
mainstone Mainstone II (PXA27x)
mcimx6ul-evk Freescale i.MX6UL Evaluation Kit (Cortex A7)
mcimx7d-sabre Freescale i.MX7 DUAL SABRE (Cortex A7)
microbit BBC micro:bit
midway Calxeda Midway (ECX-2000)
mps2-an385 ARM MPS2 with AN385 FPGA image for Cortex-M3
mps2-an505 ARM MPS2 with AN505 FPGA image for Cortex-M33
mps2-an511 ARM MPS2 with AN511 DesignStart FPGA image for Cortex-M3
mps2-an521 ARM MPS2 with AN521 FPGA image for dual Cortex-M33
musca-a ARM Musca-A board (dual Cortex-M33)
musca-b1 ARM Musca-B1 board (dual Cortex-M33)
musicpal Marvell 88w8618 / MusicPal (ARM926EJ-S)
n800 Nokia N800 tablet aka. RX-34 (OMAP2420)
n810 Nokia N810 tablet aka. RX-44 (OMAP2420)
netduino2 Netduino 2 Machine
none empty machine
nuri Samsung NURI board (Exynos4210)
palmetto-bmc OpenPOWER Palmetto BMC (ARM926EJ-S)
raspi2 Raspberry Pi 2
raspi3 Raspberry Pi 3
realview-eb ARM RealView Emulation Baseboard (ARM926EJ-S)
realview-eb-mpcore ARM RealView Emulation Baseboard (ARM11MPCore)
realview-pb-a8 ARM RealView Platform Baseboard for Cortex-A8
realview-pbx-a9 ARM RealView Platform Baseboard Explore for Cortex-A9
romulus-bmc OpenPOWER Romulus BMC (ARM1176)
sabrelite Freescale i.MX6 Quad SABRE Lite Board (Cortex A9)
sbsa-ref QEMU 'SBSA Reference' ARM Virtual Machine
smdkc210 Samsung SMDKC210 board (Exynos4210)
spitz Sharp SL-C3000 (Spitz) PDA (PXA270)
swift-bmc OpenPOWER Swift BMC (ARM1176)
sx1 Siemens SX1 (OMAP310) V2
sx1-v1 Siemens SX1 (OMAP310) V1
terrier Sharp SL-C3200 (Terrier) PDA (PXA270)
tosa Sharp SL-6000 (Tosa) PDA (PXA255)
verdex Gumstix Verdex (PXA270)
versatileab ARM Versatile/AB (ARM926EJ-S)
versatilepb ARM Versatile/PB (ARM926EJ-S)
vexpress-a15 ARM Versatile Express for Cortex-A15
vexpress-a9 ARM Versatile Express for Cortex-A9
virt-2.10 QEMU 2.10 ARM Virtual Machine
virt-2.11 QEMU 2.11 ARM Virtual Machine
virt-2.12 QEMU 2.12 ARM Virtual Machine
virt-2.6 QEMU 2.6 ARM Virtual Machine
virt-2.7 QEMU 2.7 ARM Virtual Machine
virt-2.8 QEMU 2.8 ARM Virtual Machine
virt-2.9 QEMU 2.9 ARM Virtual Machine
virt-3.0 QEMU 3.0 ARM Virtual Machine
virt-3.1 QEMU 3.1 ARM Virtual Machine
virt-4.0 QEMU 4.0 ARM Virtual Machine
virt-4.1 QEMU 4.1 ARM Virtual Machine
virt QEMU 4.2 ARM Virtual Machine (alias of virt-4.2)
virt-4.2 QEMU 4.2 ARM Virtual Machine
witherspoon-bmc OpenPOWER Witherspoon BMC (ARM1176)
xilinx-zynq-a9 Xilinx Zynq Platform Baseboard for Cortex-A9
xlnx-versal-virt Xilinx Versal Virtual development board
xlnx-zcu102 Xilinx ZynqMP ZCU102 board with 4xA53s and 2xR5Fs based on the value of smp
z2 Zipit Z2 (PXA27x)
看下virt开发板支持的cpu列表,本文以64-bit的cortex-a57为例说明:
$ qemu-system-aarch64 -M virt --cpu help
Available CPUs:
arm1026
arm1136
arm1136-r2
arm1176
arm11mpcore
arm926
arm946
cortex-a15
cortex-a53
cortex-a57
cortex-a7
cortex-a72
cortex-a8
cortex-a9
cortex-m0
cortex-m3
cortex-m33
cortex-m4
cortex-r5
cortex-r5f
max
pxa250
pxa255
pxa260
pxa261
pxa262
pxa270-a0
pxa270-a1
pxa270
pxa270-b0
pxa270-b1
pxa270-c0
pxa270-c5
sa1100
sa1110
ti925t
安装交叉编译工具
我们是在X86平台下进行的开发,目标平台是arm架构,需要安装交叉编译工具链。有关arm-linux的交叉编译器主要有:
- 针对ARM-32bit的arm-linux-gnueabi和arm-linux-gnueabihf。
- 针对ARM-64bit的aarch64-linux-gnu。
交叉编译器各版本的区别可参考《arm系列交叉编译器各版本区别》。
安装ARM-64bit的aarch64-linux-gnu版本:
$ sudo apt install gcc-aarch64-linux-gnu
查看版本:
$ aarch64-linux-gnu-gcc --version
aarch64-linux-gnu-gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
Copyright (C) 2019 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.
交叉编译ARM64 Linux内核
下载源码:
$ mkdir ~/kvm-arm
$ cd ~/kvm-arm/
$ wget https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/snapshot/linux-5.19.tar.gz
$ tar -xf linux-5.19.tar.gz
$ cd linux-5.19/
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- O=build defconfig
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- O=build -j8
说明:
- ARCH:指定目标CPU架构;
- CROSS_COMPILE:指定交叉编译器;
- O=build:O是Out的缩写,表示编译输出文件放在build目录,不跟源码混在一起,保持源码的整洁性。
- make时只有defconfig配置可选,因为 linux-5.19/arch/arm64/configs/ 目录下有且只有defconfig一个。
查看下内核编译出来的原始内核文件vmlinux,是ARM 64-bit版本。
$ file build/vmlinux
build/vmlinux: ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), statically linked, BuildID[sha1]=f2a5fd51bd2d59f90b7b26b8926f5afdeab60f36, not stripped
vmlinux不能直接引导Linux系统启动,能引导Linux系统启动的是Image文件(非压缩版)或Image.gz(压缩版),下文用到的内核镜像就是Image:
$ file build/arch/arm64/boot/Image
build/arch/arm64/boot/Image: MS-DOS executable PE32+ executable (EFI application) Aarch64 (stripped to external PDB), for MS Windows
$ file build/arch/arm64/boot/Image.gz
build/arch/arm64/boot/Image.gz: gzip compressed data, max compression, from Unix, original size modulo 2^32 36112896
交叉编译ARM64 Busybox
$ mkdir ~/kvm-arm
$ cd ~/kvm-arm/
$ wget https://busybox.net/downloads/busybox-1.35.0.tar.bz2
$ tar -xf busybox-1.35.0.tar.bz2
$ cd busybox-1.35.0/
$ export ARCH=arm64
$ export CROSS_COMPILE=aarch64-linux-gnu-
$ make menuconfig
# 修改配置,选中如下项目,静态编译
# Settings –> Build Options –> [*] Build static binary(no share libs)
# 反选如下项目,否则后续qemu执行会提示 /bin/sh:can't access tty;job control turned off
# Shells ---> [ ] Job control
$ make -j `nproc`
$ make install
装完后会 默认安装到源码目录的 _install/ 目录下:
$ ls _install/
bin linuxrc sbin usr
最关键的就是_install/bin/busybox,其他都是链接文件。
$ file _install/bin/busybox
_install/bin/busybox: ELF 64-bit LSB executable, ARM aarch64, version 1 (GNU/Linux), statically linked, BuildID[sha1]=3768162c347859f16ab4f0b01a48fb8c0502774d, for GNU/Linux 3.7.0, stripped
编译的过程中如果出现如下提示,可忽略:
Trying libraries: m resolv rt
Library m is needed, can't exclude it (yet)
Library resolv is needed, can't exclude it (yet)
Library rt is not needed, excluding it
Library m is needed, can't exclude it (yet)
Library resolv is needed, can't exclude it (yet)
Final link with: m resolv
使用busybox制作initramfs
使用busybox快速制作initramfs。
创建虚拟rootfs中的inti启动脚本,并赋予可执行权限:
$ cd ~/kvm-arm/busybox-1.35.0/_install/
$ mkdir proc sys dev tmp
$ touch init
$ chmod +x init
脚本内容:
#!/bin/sh
# 挂载一些必要的文件系统
mount -t proc none /proc
mount -t sysfs none /sys
mount -t tmpfs none /tmp
mount -t devtmpfs none /dev
echo
echo "Hello 64-bit ARM Linux"
# 显示开机消耗时间
echo "This boot took $(cut -d' ' -f1 /proc/uptime) seconds"
echo
# 停留在控制台
exec /bin/sh
制作initramfs文件,它是多个文件通过cpio打包和gzip压缩的文件,是一个cpio格式的内存文件系统。
$ find . -print0 | cpio --null -ov --format=newc | gzip -9 > ../initramfs.cpio.gz
使用QEMU启动ARM64 Linux内核
ARM Linux内核镜像和initramfs都准备好,就可以使用QEMU启动linux内核了。
以字符界面方式启动QEMU,同时日志输出到控制台:
$ qemu-system-aarch64 \
-M virt \
-cpu cortex-a57 \
-smp 8 \
-m 8G \
-kernel ./linux-5.19/build/arch/arm64/boot/Image \
-initrd ./busybox-1.35.0/initramfs.cpio.gz \
-nographic \
-append "init=/init console=ttyAMA0"
QEMU参数说明(更多可参考:Standard options):
- -M:指定模拟的开发板,可通过qemu-system-aarch64 M help查看,截至书稿时,只有virt支持64-bit ARM。
- -cpu:指定模拟的cpu,可通过qemu-system-aarch64 -M virt --cpu help查看,这里选择cortex-a57。
- -smp:指定cpu核数量,启动后可以使用nproc命令核对。
- -m:指定内存大小,virt 可支持超大内存,启动后可以使用free -h命令核对。
- -kernel:指定启动的内核镜像;
- -initrd:指定启动的内存文件系统;
- -append:传递给内核的启动参数;启动后可使用cat /proc/cmdline命令核对。
- -nographic:启动字符界面(不启动图形界面),输出重定向到宿主机命令行,与参数 console=ttyAMA0 组合使用;
9 参考