搭建qemu环境
1.安装qemu
apt install qemu-system
2.编译内核
设置gcc软链接
sudo ln -s arm-linux-gnueabihf-gcc arm-linux-gcc
sudo ln -s arm-linux-gnueabihf-ld arm-linux-ld
sudo ln -s arm-linux-gnueabihf-nm arm-linux-nm
sudo ln -s arm-linux-gnueabihf-objcopy arm-linux-objcopy
sudo ln -s arm-linux-gnueabihf-ar arm-linux-ar
sudo ln -s arm-linux-gnueabihf-strip arm-linux-strip
下载内核linux-5.6.14.tar.xz
// 解压
tar xvf linux-5.6.14.tar.xz
// 编译默认配置
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm vexpress_defconfig
// 编译安装，-j参数后面可以跟一个数字，表示并行任务的数量
// make -j4表示同时运行四个编译任务。
make CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm -j8
3.编译文件系统
下载文件系统busybox-1.37.0.tar.bz2
// 解压
tar xvf busybox-1.37.0.tar.bz2
// 编译默认配置
make defconfig
// 编译
make CROSS_COMPILE=arm-linux-gnueabi- -j8
错误：1. ‘sha1_process_block64_shaNI’ undeclared
解决1. nano .config注释下面配置
#define ENABLE_SHA1_HWACCEL
解决2. nano libbb/hash_md5_sha.c添加条件判断
修改前：
/* Used also for sha256 */
unsigned FAST_FUNC sha1_end(sha1_ctx_t *ctx, void *resbuf)
{
unsigned hash_size;
/* SHA stores total in BE, need to swap on LE arches: */
common64_end(ctx, /*swap_needed:*/ BB_LITTLE_ENDIAN);
hash_size = 8;
if (ctx->process_block == sha1_process_block64
#if ENABLE_SHA1_HWACCEL
|| ctx->process_block == sha1_process_block64_shaNI
#endif
) {
hash_size = 5;
}
/* This way we do not impose alignment constraints on resbuf: */
if (BB_LITTLE_ENDIAN) {
unsigned i;
for (i = 0; i < hash_size; ++i)
ctx->hash[i] = SWAP_BE32(ctx->hash[i]);
}
hash_size *= sizeof(ctx->hash[0]);
memcpy(resbuf, ctx->hash, hash_size);
return hash_size;
}
修改后：
/* Used also for sha256 */
unsigned FAST_FUNC sha1_end(sha1_ctx_t *ctx, void *resbuf)
{
unsigned hash_size;
/* SHA stores total in BE, need to swap on LE arches: */
common64_end(ctx, /*swap_needed:*/ BB_LITTLE_ENDIAN);
hash_size = 8;
if (ctx->process_block == sha1_process_block64
#if ENABLE_SHA1_HWACCEL
/* 添加条件判断 */
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86__64__))
|| ctx->process_block == sha1_process_block64_shaNI
#endif
#endif
) {
hash_size = 5;
}
/* This way we do not impose alignment constraints on resbuf: */
if (BB_LITTLE_ENDIAN) {
unsigned i;
for (i = 0; i < hash_size; ++i)
ctx->hash[i] = SWAP_BE32(ctx->hash[i]);
}
hash_size *= sizeof(ctx->hash[0]);
memcpy(resbuf, ctx->hash, hash_size);
return hash_size;
}
2. ‘IFLA_CAN_TERMINATION’ undeclared
修改networking/libiproute/iplink.c添加条件判断
修改前：
case ARG_termination: {
uint16_t val;
NEXT_ARG();
val = get_u16(*argv, keyword);
addattr_l(&req.n, sizeof(req), IFLA_CAN_TERMINATION, &val, sizeof(val));
break;
}
修改后：
case ARG_termination: {
uint16_t val;
NEXT_ARG();
val = get_u16(*argv, keyword);
/* 添加条件判断 */
#ifdef IFLA_CAN_TERMINATION
addattr_l(&req.n, sizeof(req), IFLA_CAN_TERMINATION, &val, sizeof(val));
#else
fprintf(stderr, "IFLA_CAN_TERMINATION is not supported on this system.\n");
#endif
break;
}
// 编译安装
make install CROSS_COMPILE=arm-linux-gnueabi- -j8
编译生成的bin文件在busybox-1.37.0/_install/目录下
4.制作根文件系统镜像
切换到busybox的上级目录，并使用如下脚本制作镜像
#!/bin/bash
mkdir -p rootfs/{dev,etc/init.d,lib}
touch rootfs/etc/init.d/rcS
#这里用双引号可能会报错
echo -e '#!/bin/sh\n' > rootfs/etc/init.d/rcS
cp busybox-1.37.0/_install/* -r rootfs/
sudo cp -P /usr/arm-linux-gnueabihf/libc/lib/* rootfs/lib/
ln -s bin/busybox rootfs/init
sudo mknod rootfs/dev/tty1 c 4 1
sudo mknod rootfs/dev/tty2 c 4 2
sudo mknod rootfs/dev/tty3 c 4 3
sudo mknod rootfs/dev/tty4 c 4 4
sudo chown root:root -R rootfs/*
sudo chmod 777 rootfs/etc/init.d/rcS
qemu-img create -f raw disk.img 512M
mkfs -t ext4 ./disk.img
mkdir -p tmpfs
sudo mount -o loop ./disk.img tmpfs/
sudo cp -r rootfs/* tmpfs/
sudo umount tmpfs
file disk.img
5.启动虚拟机开发板
sudo qemu-system-arm \
-M vexpress-a9 \
-m 512M \
-kernel linux-5.6.14/arch/arm/boot/zImage \
-dtb linux-5.6.14/arch/arm/boot/dts/vexpress-v2p-ca9.dtb \
-nographic \
-append "root=/dev/mmcblk0 rw console=ttyAMA0" \
-sd disk.img
运行成功，如下图
错误：EXT4-fs (mmcblk0): recovery complete
EXT4-fs (mmcblk0): mounted filesystem with ordered data mode. Opts: (null)
VFS: Mounted root (ext4 filesystem) on device 179:0.
Freeing unused kernel memory: 1024K
Run /sbin/init as init process
Run /etc/init as init process
Run /bin/init as init process
Run /bin/sh as init process
Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance.
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.6.14 #2
Hardware name: ARM-Versatile Express
[<80110804>] (unwind_backtrace) from [<8010c6a8>] (show_stack+0x10/0x14)
[<8010c6a8>] (show_stack) from [<807867b0>] (dump_stack+0xa0/0xb4)
[<807867b0>] (dump_stack) from [<80120f90>] (panic+0x118/0x320)
[<80120f90>] (panic) from [<807a0374>] (kernel_init+0x104/0x114)
[<807a0374>] (kernel_init) from [<801010e8>] (ret_from_fork+0x14/0x2c)
Exception stack(0x9e493fb0 to 0x9e493ff8)
3fa0: 00000000 00000000 00000000 00000000
3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
---[ end Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance.
1. <span style="color: red;">文件系统重init文件缺失</span>，检查我的文件系统中init文件正常。故排除
2.busybox编译时未进行交叉编译导致文件为不是arm架构文件，file rootfs/bin/busybox命令查看并无问题。故排除
参考博客：CentOS 7 利用qemu模拟ARM vexpress A9开发板
3.交叉编译库未正常拷贝。检查rootfs/lib文件发现其下面没有交叉编译库的内容，而是一个软链接，指向一个不存在的路径。问题定位到了，修复如下：
修改制作根文件系统镜像中sudo cp -P /usr/arm-linux-gnueabihf/lib/* rootfs/lib/为sudo cp /usr/arm-linux-gnueabihf/lib/sf/* rootfs/lib/，重新制作根文件系统镜像后正常了。
可能不同版本ubuntu安装的 gcc-arm-linux-gnueabi 库路径不同，需要自己检查一下。
Kernel panic No working init found 可能原因：
1.文件系统重init文件缺失，检查我的文件系统中init文件正常。故排除
参考博客：buildroot编译内核启动报错：Kernel panic - not syncing: No working init found问题解决
2.busybox编译时未进行交叉编译导致文件为不是arm架构文件，file rootfs/bin/busybox命令查看并无问题，故排除
参考博客：CentOS 7 利用qemu模拟ARM vexpress A9开发板
3.交叉编译库未正常拷贝。，检查rootfs/lib文件发现其下面没有交叉编译库的内容，而是一个软链接，指向一个不存在的路径。问题定位到了，修复如下：
修改制作根文件系统镜像中sudo cp -P /usr/arm-linux-gnueabihf/lib/* rootfs/lib/为sudo cp /usr/arm-linux-gnueabihf/libc/lib/* rootfs/lib/，重新制作根文件系统镜像后正常了。
可能不同版本ubuntu安装的 gcc-arm-linux-gnueabi 库路径不同，需要自己检查一下。
参考博客：启动报错：Kernel panic - not syncing: No working init found. Try passing init= option to kernel.