The QoS table showed the running VM's bandwidth while an edit changes the
definition for the next start. Each row posts average, peak and burst,
so an edit wrote the running values back over a pending change, and a
direction added while the VM ran had no row. The table shows the
persistent definition now. An edit also kept only the posted values and
dropped an inbound floor; it now updates them and keeps the rest.
Enabling hot plug on a stopped VM wrote every vCPU up to the maximum as
enabled, so a VM with 2 of 4 vCPUs booted with 4. The current vCPUs stay
enabled now; libvirt adds the rest as disabled hotpluggable vCPUs.
Only a running VM counted as active, so a paused one (or one blocked,
PM-suspended or shutting down) had its maximum and current memory written
for the next boot and nothing applied live. Every active VM now has its
current memory changed live and in its definition and keeps its maximum;
a paused guest takes the new size once resumed. The quota check follows
the same rule. Checked on a real guest: paused, shrunk, resumed, then
grown back.
A volume of an LVM or iSCSI pool can be attached: by its own path, with
the format its volume reports (raw when the pool knows none). Detaching
a disk takes each definition's own description of it, so a disk only in
the persistent definition goes too. Every NIC type can be a boot device;
bridge and direct NICs were dropped from the boot order. The video model
is a value, never parsed as XML. QoS changes clear the page's read cache.
The NIC model "default" leaves the choice to libvirt instead of writing
model "default", and rt18139 is rtl8139: a VM with either did not start
(checked on a RHEL 10 host). A migration corrects the default NIC type
setting.
