Arguments in a virtual machine configuration file are a way to extend the capability of the VM beyond just the default. For example, sound is not enabled for a VM by default. In order to give a VM the ability to play audio/video, an argument has to be passed through the VM configuration file. The following are some examples of arguments that can be used in a Proxmox VM configuration file. Arguments can be added in the following format: 

args: -<device_arguments_1> -<device_arguments_2> . . . . 
ballon: 512 
bootdisk: virtio0 
cores: 1 
ide2: none,media=cdrom 
. . . . 
. . . . 

Enable a serial device in a VM using the following code:

args: -serial /dev/ttyS0 

Enable sound in a Windows XP VM using the following code:

args: -device AC97,addr=0x18 

Enable sound in Windows 7 and later VMs using the following code:

args -device intel-hda,id=sound5,bus=pci.0,addr=0x18 -device had-micro,id=sound5-codec0,bus=sound5.0,cad=0 -device had-duplex,id=sound5-codec1,bus=sound5.0,cad=1 

Enable UUID in a VM using this line of code:

args -uuid fl234a93-20d32-2398-129032ds-2322 

Enable support for aio=native in a VM:

args: -drive file=/dev/VGGRP/VOL,if=virtio,index=1,cache=none,aio=native