recent qemu (git resp) with param like: #>qemu-kvm -S -no-user-config -nodefaults -nographic -M none -qmp monarg -pidfile pidfile will just hangs forever. no any output or errors . and when libvirt Try to get caps via QMP qemuCaps. it run above command. so virCommandProcessIO call poll() will be hangs forever. i patch the libvirt (git resp) with : diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 50712b0..915edaa 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -2377,7 +2377,6 @@ virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps, virCommandClearCaps(cmd); virCommandSetGID(cmd, runGid); virCommandSetUID(cmd, runUid); - if (virCommandRun(cmd, &status) < 0) goto cleanup; diff --git a/src/util/vircommand.c b/src/util/vircommand.c index ac56a63..84738f9 100644 --- a/src/util/vircommand.c +++ b/src/util/vircommand.c @@ -1824,6 +1824,7 @@ virCommandProcessIO(virCommandPtr cmd) int i; struct pollfd fds[3]; int nfds = 0; + int pfds = 0; if (cmd->inpipe != -1) { fds[nfds].fd = cmd->inpipe; @@ -1846,8 +1847,8 @@ virCommandProcessIO(virCommandPtr cmd) if (nfds == 0) break; - - if (poll(fds, nfds, -1) < 0) { + pfds = poll(fds, nfds, -1); + if ( pfds< 0) { if (errno == EAGAIN || errno == EINTR) continue; virReportSystemError(errno, "%s", @@ -1855,10 +1856,22 @@ virCommandProcessIO(virCommandPtr cmd) goto cleanup; } - for (i = 0; i < nfds ; i++) { - if (fds[i].revents & (POLLIN | POLLHUP | POLLERR) && + for (i = 0; i < pfds ; i++) { + if (fds[i].revents & (POLLHUP | POLLRDHUP | POLLERR | POLLNVAL)) + { + if (fds[i].fd == errfd) { + VIR_DEBUG("hangup on stderr"); + } else if (fds[i].fd == outfd) { + VIR_DEBUG("hangup on stdout"); + } else { + VIR_DEBUG("hangup on stdin"); + } + errfd = -1; + } + + if (fds[i].revents & (POLLIN | POLLHUP | POLLRDHUP | POLLERR | POLLNVAL) && (fds[i].fd == errfd || fds[i].fd == outfd)) { - char data[1024]; + char data[1024*2]; char **buf; size_t *len; int done; So everythings is OK. i use gentoo OS. qemu git source and libvirt git source.