Re: [libvirt] [PATCH 2/2] Add support for QEMU -add-fd support detection

From: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; Add support for QEMU -add-fd command line parameter detection. This intentionally rejects qemu 1.2, where 'add-fd' QMP did not allow full control of set ids, and where there was no command line counterpart, but accepts qemu 1.3. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- v1 was here: https://www.redhat.com/archives/libvir-list/2013-January/msg02056.html Okay, so most of v2 is mine, but I kept Stefan as author for his contribution in adding just one capability named QEMU_CAPS_ADD_FD. src/qemu/qemu_capabilities.c | 22 +++++++++++++++++++++- src/qemu/qemu_capabilities.h | 1 + 2 files changed, 22 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 29693c3..0820fe4 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -1,7 +1,7 @@ /* * qemu_capabilities.c: QEMU capabilities generation * - * Copyright (C) 2006-2012 Red Hat, Inc. + * Copyright (C) 2006-2013 Red Hat, Inc. * Copyright (C) 2006 Daniel P. Berrange * * This library is free software; you can redistribute it and/or @@ -39,6 +39,7 @@ #include "virnodesuspend.h" #include "qemu_monitor.h" +#include <fcntl.h> #include <sys/stat.h> #include <unistd.h> #include <sys/wait.h> @@ -203,6 +204,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST, "usb-serial", /* 125 */ "usb-net", + "add-fd", ); @@ -1961,10 +1963,28 @@ qemuCapsProbeQMPCommands(qemuCapsPtr caps, qemuCapsSet(caps, QEMU_CAPS_DRIVE_MIRROR); else if (STREQ(name, "blockdev-snapshot-sync")) qemuCapsSet(caps, QEMU_CAPS_DISK_SNAPSHOT); + else if (STREQ(name, "add-fd")) + qemuCapsSet(caps, QEMU_CAPS_ADD_FD);

VIR_FREE(name); } VIR_FREE(commands); + /* QMP add-fd was introduced in 1.2, but did not support + * management control of set numbering, and did not have a + * counterpart -add-fd command line option. We require the + * add-fd features from 1.3 or later. */ + if (qemuCapsGet(caps, QEMU_CAPS_ADD_FD)) { + int fd = open("/dev/null", O_RDONLY); + if (fd < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("unable to probe for add-fd")); + return -1; + } + if (qemuMonitorAddFd(mon, 0, fd, "/dev/null") < 0) + qemuCapsClear(caps, QEMU_CAPS_ADD_FD); + VIR_FORCE_CLOSE(fd); + } +