some times qemu command line using wrong tapfds and vhostfds

[humanux]

in qemu_vm.py make_qemu_commands()

# If nothing changed and devices exists, return imediatelly                
if (name is None and params is None and root_dir is None and self.devices is not None): 
      return self.devices

unfortunately these check ignore tap fds change, some times guest tap fds will change, for example.

1. boot a guest then shutdown it (nic.tapfds=22)
2. boot another guest with same params,( nic.tapfds=28 may be), will raise error like:

emu: -netdev tap,id=id9DXhqO,vhost=on,vhostfd=23,fd=22: TUNGETIFF ioctl() failed: Operation not permitted\nTUNSETOFFLOAD ioctl() failed: Operation not permitted\nqemu: -netdev tap,id=id9DXhqO,vhost=on,vhostfd=23,fd=22: vhost-net requested but could not be initialized\nqemu: -netdev tap,id=id9DXhqO,vhost=on,vhostfd=23,fd=22: Device 'tap' could not be initialized")

need update nic.tapfds and vhostfds before return self.device, or update them during generate qemu command line.

[humanux]

@jzupka please help to fix this issue.

[jzupka]

@humanux hi, I'll take a look on that.

[jzupka]

@humanux I try to create patch which recreate system dependent devs (nic, redirs, and what will be necessary more).

[jzupka]

@humanux After quick fix of this problem I'll try to prepare better solution which totally splits preparation of qemu and system specific (create fd etc) things.

[humanux]

@jzupka thanks for your quickly reply. wait your fix patch