i want add sound card to domain xml when guest start,after google,i found libvirt provide hook function. i follow the instruction to make a python,and boot a guest,but after use "virsh edit" its still dont have sound card config /etc/libvirt/hooks/qemu: #!/usr/bin/python import sys import re import os hooklog = '/tmp/hook.log' log = open(hooklog, 'w') stdinxml = sys.stdin.readlines() if sys.argv[2] == 'start': log.write("hook start,domain name: %s \n" % sys.argv[1]) maxslot=-1 for line in stdinxml: slotm = re.search("slot='(?P<slotnum>0x[0-9a-fA-F]{2})'", line) if slotm: slotnum = int(slotm.group('slotnum'),0) if slotnum > maxslot: maxslot = slotnum if '</devices>' in line: log.write("insert sound card config \n") slotnum = maxslot + 1 line = " <sound model='ich6'>\n" line = line + " <address type='pci' domain='0x0000' bus='0x00' slot='0x%0.2X' function='0x0'/>\n" % slotnum line = line + " </sound>\n" line = line + " </devices>\n" stdoutxml = ''.join(line) sys.stdout.write(stdoutxml) tail -f /tmp/hook.log: hook start,domain name: instance-00000222 insert sound card config tail /var/log/libvirt/libvirtd.log: 2014-04-16 07:13:39.159+0000: 52199: warning : qemuDomainObjTaint:1377 : Domain id=81 name='instance-00000222' uuid=974d62b7-f316-4f20-a91c-d11cb85980fe is tainted: high-privileges in these log,hook script seems to executed,but not effective. can anyone tell me where is wrong?