vnc: 0.903 network: 0.884 device: 0.865 socket: 0.784 performance: 0.699 semantic: 0.673 graphic: 0.616 files: 0.586 boot: 0.494 PID: 0.354 debug: 0.333 other: 0.319 permissions: 0.296 KVM: 0.295 VNC/RFB: QEMU reports incorrect name (length) If the name of a machine (as set with the -name argument) has a length longer than 1024, (RFB) VNC clients will not receive a correct RFB ServerInit message. I suspect this is the problem: https://github.com/qemu/qemu/blob/master/ui/vnc.c#L2463 The return value of snprintf is used as the value for the name-length field in the ServerInit message. This is problematic for names that were truncated to 1024, as the length will now be bigger than the actual name. I think a quick fix would be to simply report min(size,1024) to the client... The right fix here is to switch to use g_strdup_printf and avoid a fixed length stack buffer entirely. Fix has been committed: http://git.qemu.org/?p=qemu.git;a=commitdiff;h=97efe4f961dcf5a0126