Hi, I tested "virsh setvcpus" command and it did not work like the following: # virsh setvcpus RHEL5.5GA_Guest.img 2 error: internal error unable to execute QEMU command 'cpu_set': The command cpu_set has not been ound # Has this problem been fixed already on upstream ? o Test environment Host OS: RHEL6.0 (x86_64) qemu-kvm: 0.12.1.2-2.113.el6 libvirt : 0.8.1-27.el6 Guetst OS: RHEL5.5 o GDB output (gdb) b qerror_report_internal Breakpoint 1 at 0x497a50: file qerror.c, line 412. (gdb) c Continuing. [New Thread 0x7f726a9fc710 (LWP 23964)] Breakpoint 1, qerror_report_internal ( file=0x57e9d0 "/builddir/build/BUILD/qemu-kvm-0.12.1.2/monitor.c", linenr=4427, func=0x582af0 "handle_qmp_command", fmt=0x57ee90 "{ 'class': 'CommandNotFound', 'data': { 'name': %s } }") at qerror.c:412 412 { (gdb) bt #0 qerror_report_internal ( file=0x57e9d0 "/builddir/build/BUILD/qemu-kvm-0.12.1.2/monitor.c", linenr=4427, func=0x582af0 "handle_qmp_command", fmt=0x57ee90 "{ 'class': 'CommandNotFound', 'data': { 'name': %s } }") at qerror.c:412 #1 0x00000000004133ae in handle_qmp_command (parser=<value optimized out>, tokens=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4427 #2 0x0000000000495d52 in json_message_process_token (lexer=0x1ab5d70, token=0x22037b0, type=JSON_OPERATOR, x=61, y=9170) at json-streamer.c:56 #3 0x0000000000495ab3 in json_lexer_feed_char (lexer=0x1ab5d70, ch=125 '}') at json-lexer.c:299 #4 0x0000000000495be7 in json_lexer_feed (lexer=0x1ab5d70, buffer=0x7ffff19b4510 "}F\232\001", size=1) at json-lexer.c:322 #5 0x00000000004124d2 in monitor_control_read (opaque=<value optimized out>, buf=<value optimized out>, size=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/monitor.c:4478 #6 0x00000000004b6b8a in qemu_chr_read (opaque=0x19a43a0) at qemu-char.c:154 #7 tcp_chr_read (opaque=0x19a43a0) at qemu-char.c:2072 #8 0x000000000040b4af in main_loop_wait (timeout=1000) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4234 #9 0x0000000000428a2a in kvm_main_loop () at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2133 #10 0x000000000040e5cb in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4444 #11 main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:6601 (gdb) Thanks Ken'ichi Ohmichi