How about a more helpful error message? Perhaps libvirtd could notice that dnsmasq is already running and say "please disable dnsmasq on interface xyz". Or maybe dnsmasq itself could be noticing that?
How about a more helpful error message? Perhaps libvirtd could notice that dnsmasq is already running and say "please disable dnsmasq on interface xyz". Or maybe dnsmasq itself could be noticing that?