Hi,
I am new bee to snapshot feature and how to use it correctly. My requirement is
simple, in that I want to snapshot the running VM and save the snapshot file.
Using the snapshot file, I want to boot the VM directly to snapshot state.I
came across the qemu monitors "savevm" and "loadvm" commands. The following are
the steps I follow to create snapshot and load the snapshot,Step 1: Launch VM
using below command,
qemu-system-arm -M arm-machine -m 512M -name my_name -kernel main.rbx -serial
pty -serial vc -serial vc -serial vc -drive
if=none,format=qcow2,file=/home/sridhar/qemu_disk_image/dummy.qcow2
Step 2: Save the snapshot (issue savevm from qemu monitor)
--> savevm my_snapshot
Step 3 Launch the VM using snapshot image saved in step 2,
qemu-system-arm -M arm-machine -m 512M -name my_name -kernel main.rbx -serial
pty -serial vc -serial vc -serial vc -drive
if=none,format=qcow2,file=/home/sridhar/qemu_disk_image/dummy.qcow2 -loadvm
my_snapshot
With this approach, I am seeing that RAM contents are not getting saved when I
issue "savevm" command. I have copied the part of the file, when the function
"ram_control_save_page" returns "RAM_SAVE_CONTROL_NOT_SUPP" and hence the page
is not getting saved.
size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
ram_addr_t offset, size_t size,
uint64_t *bytes_sent)
{
if (f->hooks && f->hooks->save_page) {
int ret = f->hooks->save_page(f, f->opaque, block_offset,
offset, size, bytes_sent);
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_sent && *bytes_sent > 0) {
qemu_update_position(f, *bytes_sent);
} else if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
return ret;
}
return RAM_SAVE_CONTROL_NOT_SUPP;
}
Is there anything that I am missing here in the understanding "savevm" and
"loadvm" commands?
Thanks
