解决，估计是需要 exec switch_root 方式调用 switch_root 才不会出错
复制内容到剪贴板
代码:
#!/bin/sh
mount -t proc /proc /proc
mount -t sysfs /sys /sys
#mount -o mode=0755 -t tmpfs /dev /dev
echo Mknod...
mknod /dev/null c 1 3
mknod /dev/zero c 1 5
mknod /dev/systty c 4 0
mknod /dev/tty c 5 0
mknod /dev/console c 5 1
echo Insmod ...
insmod /lib/aufs.ko
insmod /lib/unlzma.ko
insmod /lib/sqlzma.ko
insmod /lib/squashfs.ko
#echo 0x0100 > /proc/sys/kernel/real-root-dev
echo Start udev...
/bin/udevd &
sleep 2
echo Scan device...
/bin/udevadm trigger
sleep 2
#echo Start a sh prompt...
#/bin/sh
mkdir -p /usbdisk
mkdir -p /aufs
mkdir -p /squashfs
mount -t vfat /dev/sda1 /usbdisk -o ro
mount -t tmpfs /aufs /aufs
mount -t squashfs /usbdisk/mgc.squ /squashfs -o ro
mount -t aufs -o br:/aufs=rw:/squashfs=ro /sysroot /sysroot
umount /proc
umount /sys
#ps
killall udevd
cd /sysroot
exec /bin/switch_root /sysroot /sbin/init 
