Question： qemux86-64 reboot hangs at "reboot: machine restart"

["Xu, Yanfei" <yanfei.xu@windriver.com>]

Hi experts，

When I used qemu6.0 to boot a VM, then I found that it will hang after I
execute "reboot" command. With a long time waiting, It didn't reboot and
leave the message as blow:
------------cut here------------
root@qemux86-64:~# reboot

Broadcast message from root@qemux86-64 (ttyS0) (Fri Jul  9 09:09:31 2021):

The system is going down for reboot NOW!
INIT: Switching to runlevel: 6
INIT: Sending processes configured via /etc/inittab the TERM signal
Stopping syslogd/klogd: stopped syslogd (pid 255)
stopped klogd (pid 258)
done
Deconfiguring network interfaces... ifdown: interface lo not configured
done.
Sending all processes the TERM signal...
Sending all processes the KILL signal...
Unmounting remote filesystems...
Deactivating swap...
Unmounting local filesystems...
[   38.388532] EXT4-fs (vda): re-mounted. Opts: (null)
Rebooting... [   38.534593] reboot: Restarting system
[   38.534844] reboot: machine restart



The command booting VM I used is "

/path/to/qemu-system-x86_64 -device 
virtio-net-pci,netdev=net0,mac=52:54:00:12:35:02 -netdev 
user,id=net0,hostfwd=tcp::2222-:22,hostfwd=tcp::2323-:23,tftp=/path/to/images/qemux86-64 
-object rng-random,filename=/dev/urandom,id=rng0 -device 
virtio-rng-pci,rng=rng0 -drive 
file=/path/to/core-image-minimal-qemux86-64-20210707062347.rootfs.ext4,if=virtio,format=raw 
-usb -device usb-tablet -cpu IvyBridge -machine q35 -smp 4 -m 256 
-serial mon:stdio -serial null -nographic -kernel 
/path/to/bzImage--5.10.41.bin -append root=/dev/vda rw  reboot=a 
mem=256M ip=dhcp console=ttyS0 console=ttyS1 oprofile.timer=1 
tsc=reliable no_timer_check rcupdate.rcu_expedited=1
"


I also tried the qemu5.2, It still has this issue. Did I miss something? 
Could you please give me some advises? Thanks!



Regards,
Yanfei