Does qemu emulator have checkpoint function?

A savevm snapshot should do what you want. The short answer is that you need to set up a QCOW2 disk for the snapshots to be saved to, and then in the monitor you can use the 'savevm' command to take the snapshot. Then the command line '-loadvm' option will let you resume from there. This all works fine in emulation of AArch64.

https://translatedcode.wordpress.com/2015/07/06/tricks-for-debugging-qemu-savevm-snapshots/ has a more detailed tutorial.

Minimal example

Peter's answer just worked for me, but let me provide a fully reproducible example.

I have fully automated everything at: https://github.com/cirosantilli/linux-kernel-module-cheat/tree/1e0f0b492855219351b0bfa2eec4d3a6811fcaaa#snapshot

The key step is to convert the image to qcow2 as explained at: https://docs.openstack.org/image-guide/convert-images.html

cd buildroot/output.x86_64~/images qemu-img convert -f raw -O qcow2 rootfs.ext2 rootfs.ext2.qcow2 

And the final QEMU command used was:

./buildroot/output.x86_64~/host/usr/bin/qemu-system-x86_64 -m 128M -monitor telnet::45454,server,nowait -netdev user,hostfwd=tcp::45455-:45455,id=net0 -smp 1 -M pc -append 'root=/dev/vda nopat nokaslr norandmaps printk.devkmsg=on printk.time=y console=ttyS0' -device edu -device virtio-net-pci,netdev=net0 -drive file=./buildroot/output.x86_64~/images/rootfs.ext2.qcow2,if=virtio,format=qcow2 -kernel ./buildroot/output.x86_64~/images/bzImage -nographic 

To test it out, login into the VM, and run:

i=0; while true; do echo $i; i=$(($i + 1)); sleep 1; done 

Then on another shell, open the monitor:

telnet localhost 45454 savevm my_snap_id 

The counting continues. Then, if we load the vm:

loadvm my_snap_id 

the counting goes back to where we saved. This shows that CPU and memory states were reverted.

We can also verify that the disk state is also reversed. Guest:

echo 0 >f 

Monitor:

savevm my_snap_id 

Guest:

echo 1 >f 

Monitor:

loadvm my_snap_id 

Guest:

cat f 

And the output is 0.