This is workaround for missing libxl/libvirt functionality: QubesOS/qubes-issues#1426
Also it should improve system shutdown time, as this is the situation
where all the VMs are shutting down simultaneously.
FixesQubesOS/qubes-issues#1425
Mostly done. Things still using xenstore/not working at all:
- DispVM
- qubesutils.py (especially qvm-block and qvm-usb code)
- external IP change notification for ProxyVM (should be done via RPC
service)
This makes easier to import right objects in submodules (only one
object). This also implement lazy connection - at first access, not at
module import, which speeds up tools, which doesn't need runtime
information (like qvm-prefs or qvm-service). In the future this will
ease migration from xenstore to QubesDB.
Also implement "offline mode" - operate on qubes.xml without connecting
to VMM - raise exception at such try.
This is needed to run tools during installation, where only minimal
set of services are started, especially no libvirt.
When netvm and firewallvm is shut down, netvm handling code will
try to revoke firewallvm access to external IP. But if netvm shutdown
happens in the meantime, xenstore will throw ENOENT error.
