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[Libvir] RFC: Supporting serial & parallel ports for QEMU (and improving Xen)
by Daniel P. Berrange 26 Feb '08

26 Feb '08

One user's feature request for our QEMU driver is to support serial ports. Easy you might think... you'd be wrong :-) On Xen we have very simple approach. When creating a guest simply add <console/> And it'll cause a serial port to be setup with an autoallocated pty, so you get back <console pty='/dev/pts/5'/> In retrospect calling it 'console' was dumb, but hey we're stuck with that now and its only a tiny naming issue so I don't mind really. We can do the same thing with QEMU quite easily. QEMU, however, supports many many many more ways to hooking up the serial port to Dom0. Indeed so does Xen fullyvirt, but we don't expose this ability. Parallel ports have identical config syntax to serial ports so we might as well deal with both at once. So, here's a stripped down version of the QEMU docs: [quote http://fabrice.bellard.free.fr/qemu/qemu-doc.html#SEC10] `-serial dev' Redirect the virtual serial port to host character device dev. The default device is vc in graphical mode and stdio in non graphical mode. This option can be used several times to simulate up to 4 serials ports. Use -serial none to disable all serial ports. Available character devices are: vc Virtual console pty [Linux only] Pseudo TTY (a new PTY is automatically allocated) none No device is allocated. null void device /dev/XXX [Linux only] Use host tty, e.g. `/dev/ttyS0'. The host serial port parameters are set according to the emulated ones. /dev/parportN [Linux only, parallel port only] Use host parallel port N. Currently only SPP parallel port features can be used. file:filename Write output to filename. No character can be read. stdio [Unix only] standard input/output pipe:filename name pipe filename COMn [Windows only] Use host serial port n udp:[remote_host]:remote_port[@[src_ip]:src_port] This implements UDP Net Console. tcp:[host]:port[,server][,nowait][,nodelay] The TCP Net Console has two modes of operation. telnet:host:port[,server][,nowait][,nodelay] The telnet protocol is used instead of raw tcp sockets. unix:path[,server][,nowait] A unix domain socket is used instead of a tcp socket. [/quote] I don't see any reason to not support all/most of these options. The things I don't like here is that /dev/XXX, vs /dev/parportN, vs COMn differences for connecting guest <-> host passthrough of the devices. I figure it could be simpler if it was just represented as 'n' and we'd translate that to be /dev/ttyS[n] or /dev/parport[n] or COM[n] as needed. The question as ever is how to represent this in XML. For serial ports we'll stick with '<console>', while parallel ports we might as well use a better named '<parallel>'. Next up, I think should use a 'type' attribute on this element to determine the main way ot connecting the device, and then more type specific attributes or sub-elements as needed. If 'type' was not specified then use a default of 'pty', since that gives compatability with existing practice. As an illustrative example /* * Parse the XML definition for a character device * * Top level node will be <console> or <parallel>, but all attributes * and sub-elements are identical. * * type=vc|pty|null|host|file|pipe|udp|tcp|telnet, default is pty * * <console type='vc'/> * * <console type='pty' pty='/dev/pts/3'/> * * <console type='null'/> * * <console type='host' port='3'/> * * <console type='file' path='/some/file'/> * * <console type='pipe' path='/some/file'/> * * <console type='udp'> * <sendto port='12356'/> * </console> * * <console type='udp'> * <sendto addr='127.0.0.1' port='12356'/> * </console> * * <console type='udp'> * <sendto addr='127.0.0.1' port='12356'/> * <bind port='12356'/> * </console> * * <console type='udp'> * <sendto addr='127.0.0.1' port='12356'/> * <bind addr='127.0.0.1' port='12356'/> * </console> * * <console type='tcp'> * <listen port='12356'/> * </console> * * <console type='tcp'> * <listen addr='127.0.0.1' port='12356'> * <nowait/> * <nodelay/> * </listen> * </console> * * <console type='tcp'> * <connect addr='127.0.0.1' port='12356'> * <nodelay/> * </connect> * </console> * * <console type='telnet'> * <listen addr='127.0.0.1' port='12356'/> * </console> * * <console type='telnet'> * <connect addr='127.0.0.1' port='12356'/> * </console> * */ BTW, the udp, tcp, telnet options are only available on QEMU >= 0.9.0. We already have ability to detect / validate that for both Xen & QEMU drivers. NB, whereever there are IP addresses, hostnames can be used too, hence I call the attriute 'addr' instead of 'ip' Regards, Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=|

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[Libvir] How to stop 'make install' clobbering /etc/libvirt/libvirtd.conf
by Richard W.M. Jones 26 Feb '08

26 Feb '08

Currently 'make install' clobbers configuration files, in particular /etc/libvirt/libvirtd.conf. It shouldn't. Does anyone know how to persuade automake to stop it from doing this? As far as I can see the only way would be to write a custom install rule. Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://et.redhat.com/~rjones/virt-top

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[Libvir] default hypervisor selection
by Daniel Veillard 26 Feb '08

26 Feb '08

While going though the ovirt installation steps I got annoyed with the need to add "-c qemu:///system" each time we are trying to start a virsh command if using KVM. The dfault setup is basically to assume a Xen hypervisor if the URI is not specified, this is glued in the do_open internal opening routine associated to the opening of connections: -------------------------------------- static virConnectPtr do_open (const char *name, virConnectAuthPtr auth, int flags) { int i, res; virConnectPtr ret = NULL; xmlURIPtr uri; /* Convert NULL or "" to xen:/// for back compat */ if (!name || name[0] == '\0') name = "xen:///"; -------------------------------------- In one hand this is the default behaviour of the library, but in my opinion it's not very smart. We should be able to be smarter than that, for example: - if /proc/xen doesn't exist (on linux, or /dev/xen on Solaris) well we should not do that we are pretty sure we will get an error when trying to connect - if /proc/vz is present, well it's very likely that if the kernel has been compiled with OpenVZ support, it's likely to be used as the default virtualization - if there is a kvm module loaded well we should probably use qemu:///system if running as root or qemu:///session otherwise I guess on Solaris an easy heuristic would allow to pick the right hypervisor by default too. At some point we may have multiple hypervisor support simultaneously on a linux system thanks to pv_ops, but right now it doesn't make too much sense to force a default Xen connection even when we know it won't work. For a virsh specific solution there is the VIRSH_DEFAULT_CONNECT_URI environment variable, but it's not really user friendly and not very generic, What do people think ? I would be tempted to provide a patch to change do_open() behaviour on linux in the case name is NULL or "", and then check what hypervisor might be present and running, Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/

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[Libvir] [Discussion] 0/4 Implement DHCP host mappings for virtual networks
by Richard W.M. Jones 25 Feb '08

25 Feb '08

This is a series of patches to implement DHCP IP & hostname mappings for libvirt virtual networks. ** NOTE: This patch is not to be applied. There is some memory corruption bug which I'm still tracking down. What this patch allows you to do is to create a table of IP address to host (defined by its hardware / MAC address) for each virtual network. Optionally you can also assign a hostname. When a host starts up and requests an IP address through DHCP, if it is in this table then it gets the fixed IP address from the table and, optionally, a fixed hostname. Four new API calls are added. Two are required to list the contents of the mapping table. Two more allow you to add and delete a mapping. The mapping table is semi-permanent. It is stored in /var/lib/libvirt/hosts-<networkname>.conf and survives across libvirtd restarts. The implementation simply uses dnsmasq's --dhcp-hostsfile flag. Refer to the dnsmasq(1) manual page. Rich. -- Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/ Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 03798903

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[Libvir] [PATCH] Avoid new "make syntax-check" failures.
by Jim Meyering 25 Feb '08

25 Feb '08

With recent changes, I introduced some new "make syntax-check" failures. Also, there were two remaining invalid uses of write(2). This fixes all that. Avoid new "make syntax-check" failures. * .x-sc_avoid_write: Exempt src/util-lib.c, too. * Makefile.maint (sc_unmarked_diagnostics): Filter out false positives. * src/storage_backend_fs.c (virStorageBackendFileSystemVolCreate): Use safewrite, not write. * src/storage_backend_logical.c (virStorageBackendLogicalBuildPool): Likewise. --- .x-sc_avoid_write | 1 + Makefile.maint | 6 +++++- src/storage_backend_fs.c | 2 +- src/storage_backend_logical.c | 2 +- 4 files changed, 8 insertions(+), 3 deletions(-) diff --git a/.x-sc_avoid_write b/.x-sc_avoid_write index 72a196d..fe38d83 100644 --- a/.x-sc_avoid_write +++ b/.x-sc_avoid_write @@ -1,2 +1,3 @@ ^src/util\.c$ ^src/xend_internal\.c$ +^src/util-lib\.c$ diff --git a/Makefile.maint b/Makefile.maint index fe964a5..0c3acf8 100644 --- a/Makefile.maint +++ b/Makefile.maint @@ -304,6 +304,9 @@ err_func_re = \ # Look for diagnostics that aren't marked for translation. # This won't find any for which error's format string is on a separate line. +# The sed filters eliminate false-positives like these: +# _("...: " +# "%s", _("no storage vol w..." sc_unmarked_diagnostics: @grep -nE \ '\<(vshError|error) \([^"]*"[^"]*[a-z]{3}' $$($(CVS_LIST_EXCEPT)) \ @@ -312,7 +315,8 @@ sc_unmarked_diagnostics: exit 1; } || : @{ grep -nE '\<$(err_func_re) *\(.*;$$' $$($(CVS_LIST_EXCEPT)); \ grep -A1 -nE '\<$(err_func_re) *\(.*,$$' $$($(CVS_LIST_EXCEPT)); } \ - | grep '[ ]"' && \ + | sed 's/_("[^"][^"]*"//;s/[ ]"%s"//' \ + | grep '[ ]"' && \ { echo '$(ME): found unmarked diagnostic(s)' 1>&2; \ exit 1; } || : diff --git a/src/storage_backend_fs.c b/src/storage_backend_fs.c index 9425cbc..1d540e1 100644 --- a/src/storage_backend_fs.c +++ b/src/storage_backend_fs.c @@ -854,7 +854,7 @@ virStorageBackendFileSystemVolCreate(virConnectPtr conn, int bytes = sizeof(zeros); if (bytes > remain) bytes = remain; - if ((bytes = write(fd, zeros, bytes)) < 0) { + if ((bytes = safewrite(fd, zeros, bytes)) < 0) { virStorageReportError(conn, VIR_ERR_INTERNAL_ERROR, _("cannot fill file '%s': %s"), vol->target.path, strerror(errno)); diff --git a/src/storage_backend_logical.c b/src/storage_backend_logical.c index a70c087..f8a075d 100644 --- a/src/storage_backend_logical.c +++ b/src/storage_backend_logical.c @@ -287,7 +287,7 @@ virStorageBackendLogicalBuildPool(virConnectPtr conn, strerror(errno)); goto cleanup; } - if (write(fd, zeros, sizeof(zeros)) != sizeof(zeros)) { + if (safewrite(fd, zeros, sizeof(zeros)) < 0) { virStorageReportError(conn, VIR_ERR_INTERNAL_ERROR, _("cannot clear device header %s"), strerror(errno)); -- 1.5.4.2.185.gf5f8

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[Libvir] Error - when compiling sample libvirt program - Failed to find libvirt proxy
by Sunil Lingappa 25 Feb '08

25 Feb '08

Hello Everybody I am trying to compile the sample program which is present at the libvirt.org sample program section. I am running the program which is used to retrieve domain information. While i am able to compile it with success, when i run it i get the following error : *" failed to find libvirt_proxy " * But the output is still displayed. Can anybody please help me how to overcome this error message. find below the patch level info : rpm -qa | grep libvirt libvirt-devel-0.2.0-0.16 libvirt-0.2.0-0.16 libvirt-python-0.2.0-0.16 Thanks & Best Regards Sunil

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[Libvir] [PATCH] 1/2: Move safewrite and saferead to a separate file.
by Jim Meyering 25 Feb '08

25 Feb '08

Move safewrite and saferead to a separate file. We currently use safewrite from inside libvirt and don't want to publish any such function name. However, we do want to use it in applications like virsh, libvirtd and libvirt_proxy that link with libvirt. To that end, this change moves that function definition (along with the nearly identical saferead) into a new file, util-lib.c. To avoid maintaining separate copies of even such small functions, we simply include that new file from util.c. Then, the separate applications that need to use safewrite simply compile and link with util-lib.c. Of course, this does mean that each of those applications will containing two copies of these functions. However, the functions are so small that it's not worth worrying about that. * src/util.c (saferead, safewrite): Move function definitions to util-lib.c and include that .c file. * src/util-lib.c (saferead, safewrite): New file. Functions from src/util.c with slight change (s/int r =/ssize_t r =/) to reflect read/write return type. * src/util-lib.h: Declare the two moved functions. * src/util.h: Remove declarations. Include src/util-lib.h. * proxy/Makefile.am (libvirt_proxy_SOURCES): Add src/util-lib.c. * qemud/Makefile.am (libvirtd_SOURCES): Likewise. * src/Makefile.am (virsh_SOURCES): Add util-lib.c. Remove some SP-before-TAB. Signed-off-by: Jim Meyering <meyering(a)redhat.com> --- proxy/Makefile.am | 6 +++- proxy/libvirt_proxy.c | 16 ++++---------- qemud/Makefile.am | 3 +- src/Makefile.am | 16 +++++++------- src/util-lib.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++ src/util-lib.h | 16 +++++++++++++++ src/util.c | 43 ++------------------------------------- src/util.h | 10 ++++---- 8 files changed, 95 insertions(+), 67 deletions(-) create mode 100644 src/util-lib.c create mode 100644 src/util-lib.h diff --git a/proxy/Makefile.am b/proxy/Makefile.am index ff9a3eb..68e3317 100644 --- a/proxy/Makefile.am +++ b/proxy/Makefile.am @@ -12,11 +12,13 @@ libexec_PROGRAMS = libvirt_proxy libvirt_proxy_SOURCES = libvirt_proxy.c @top_srcdir@/src/xend_internal.c \ @top_srcdir@/src/xen_internal.c @top_srcdir@/src/virterror.c \ @top_srcdir@/src/sexpr.c @top_srcdir@/src/xml.c \ - @top_srcdir@/src/xs_internal.c @top_srcdir@/src/buf.c @top_srcdir@/src/uuid.c + @top_srcdir@/src/xs_internal.c @top_srcdir@/src/buf.c \ + @top_srcdir@/src/util-lib.c \ + @top_srcdir@/src/uuid.c libvirt_proxy_LDFLAGS = $(WARN_CFLAGS) libvirt_proxy_DEPENDENCIES = libvirt_proxy_LDADD = install-exec-hook: chmod u+s $(DESTDIR)$(libexecdir)/libvirt_proxy -endif \ No newline at end of file +endif diff --git a/proxy/libvirt_proxy.c b/proxy/libvirt_proxy.c index d96d3db..a22ba6c 100644 --- a/proxy/libvirt_proxy.c +++ b/proxy/libvirt_proxy.c @@ -2,7 +2,7 @@ * proxy_svr.c: root suid proxy server for Xen access to APIs with no * side effects from unauthenticated clients. * - * Copyright (C) 2006, 2007 Red Hat, Inc. + * Copyright (C) 2006, 2007, 2008 Red Hat, Inc. * * See COPYING.LIB for the License of this software * @@ -26,6 +26,7 @@ #include "internal.h" #include "proxy_internal.h" +#include "util.h" #include "xen_internal.h" #include "xend_internal.h" #include "xs_internal.h" @@ -317,19 +318,12 @@ proxyWriteClientSocket(int nr, virProxyPacketPtr req) { return(-1); } -retry: - ret = write(pollInfos[nr].fd, (char *) req, req->len); + ret = safewrite(pollInfos[nr].fd, (char *) req, req->len); if (ret < 0) { - if (errno == EINTR) { - if (debug > 0) - fprintf(stderr, "write socket %d to client %d interrupted\n", - pollInfos[nr].fd, nr); - goto retry; - } fprintf(stderr, "write %d bytes to socket %d from client %d failed\n", req->len, pollInfos[nr].fd, nr); - proxyCloseClientSocket(nr); - return(-1); + proxyCloseClientSocket(nr); + return(-1); } if (ret == 0) { if (debug) diff --git a/qemud/Makefile.am b/qemud/Makefile.am index db6adb1..1e1f861 100644 --- a/qemud/Makefile.am +++ b/qemud/Makefile.am @@ -42,6 +42,7 @@ libvirtd_SOURCES = \ qemud.c internal.h \ remote_protocol.h remote_protocol.c \ remote.c \ + $(srcdir)/../src/util-lib.c \ event.c event.h #-D_XOPEN_SOURCE=600 -D_XOPEN_SOURCE_EXTENDED=1 -D_POSIX_C_SOURCE=199506L @@ -151,4 +152,4 @@ uninstall-init: endif # DBUS_INIT_SCRIPTS_RED_HAT -endif # WITH_LIBVIRTD \ No newline at end of file +endif # WITH_LIBVIRTD diff --git a/src/Makefile.am b/src/Makefile.am index 7bbf816..1da0d73 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -51,21 +51,21 @@ CLIENT_SOURCES = \ conf.c conf.h \ xm_internal.c xm_internal.h \ remote_internal.c remote_internal.h \ - bridge.c bridge.h \ - iptables.c iptables.h \ - uuid.c uuid.h \ - qemu_driver.c qemu_driver.h \ + bridge.c bridge.h \ + iptables.c iptables.h \ + uuid.c uuid.h \ + qemu_driver.c qemu_driver.h \ qemu_conf.c qemu_conf.h \ openvz_conf.c openvz_conf.h \ - openvz_driver.c openvz_driver.h \ + openvz_driver.c openvz_driver.h \ nodeinfo.h nodeinfo.c \ storage_conf.h storage_conf.c \ storage_driver.h storage_driver.c \ storage_backend.h storage_backend.c \ - storage_backend_fs.h storage_backend_fs.c \ + storage_backend_fs.h storage_backend_fs.c \ util.c util.h -SERVER_SOURCES = \ +SERVER_SOURCES = \ ../qemud/remote_protocol.c ../qemud/remote_protocol.h if WITH_STORAGE_LVM @@ -100,7 +100,7 @@ libvirt_la_CFLAGS = $(COVERAGE_CFLAGS) bin_PROGRAMS = virsh -virsh_SOURCES = virsh.c console.c console.h +virsh_SOURCES = virsh.c console.c console.h util-lib.c virsh_LDFLAGS = $(WARN_CFLAGS) $(COVERAGE_LDFLAGS) virsh_DEPENDENCIES = $(DEPS) virsh_LDADD = $(LDADDS) $(VIRSH_LIBS) diff --git a/src/util-lib.c b/src/util-lib.c new file mode 100644 index 0000000..92496cd --- /dev/null +++ b/src/util-lib.c @@ -0,0 +1,52 @@ +/* + * common, generic utility functions + * + * Copyright (C) 2006, 2007, 2008 Red Hat, Inc. + * See COPYING.LIB for the License of this software + */ + +#include <config.h> + +#include <unistd.h> +#include <errno.h> + +#include "util-lib.h" + +/* Like read(), but restarts after EINTR */ +int saferead(int fd, void *buf, size_t count) +{ + size_t nread = 0; + while (count > 0) { + ssize_t r = read(fd, buf, count); + if (r < 0 && errno == EINTR) + continue; + if (r < 0) + return r; + if (r == 0) + return nread; + buf = (char *)buf + r; + count -= r; + nread += r; + } + return nread; +} + +/* Like write(), but restarts after EINTR */ +ssize_t safewrite(int fd, const void *buf, size_t count) +{ + size_t nwritten = 0; + while (count > 0) { + ssize_t r = write(fd, buf, count); + + if (r < 0 && errno == EINTR) + continue; + if (r < 0) + return r; + if (r == 0) + return nwritten; + buf = (const char *)buf + r; + count -= r; + nwritten += r; + } + return nwritten; +} diff --git a/src/util-lib.h b/src/util-lib.h new file mode 100644 index 0000000..4a14810 --- /dev/null +++ b/src/util-lib.h @@ -0,0 +1,16 @@ +/* + * private utility functions + * + * Copyright (C) 2008 Red Hat, Inc. + * See COPYING.LIB for the License of this software + */ + +#ifndef __UTIL_LIB_H__ +#define __UTIL_LIB_H__ + +#include <sys/types.h> + +int saferead(int fd, void *buf, size_t count); +ssize_t safewrite(int fd, const void *buf, size_t count); + +#endif diff --git a/src/util.c b/src/util.c index 19131a7..67cb0b8 100644 --- a/src/util.c +++ b/src/util.c @@ -1,7 +1,7 @@ /* * utils.c: common, generic utility functions * - * Copyright (C) 2006, 2007 Red Hat, Inc. + * Copyright (C) 2006, 2007, 2008 Red Hat, Inc. * Copyright (C) 2006 Daniel P. Berrange * Copyright (C) 2006, 2007 Binary Karma * Copyright (C) 2006 Shuveb Hussain @@ -46,6 +46,8 @@ #include "buf.h" #include "util.h" +#include "util-lib.c" + #define MAX_ERROR_LEN 1024 #define virLog(msg...) fprintf(stderr, msg) @@ -276,45 +278,6 @@ virExecNonBlock(virConnectPtr conn, #endif /* __MINGW32__ */ -/* Like read(), but restarts after EINTR */ -int saferead(int fd, void *buf, size_t count) -{ - size_t nread = 0; - while (count > 0) { - int r = read(fd, buf, count); - if (r < 0 && errno == EINTR) - continue; - if (r < 0) - return r; - if (r == 0) - return nread; - buf = (unsigned char *)buf + r; - count -= r; - nread += r; - } - return nread; -} - -/* Like write(), but restarts after EINTR */ -ssize_t safewrite(int fd, const void *buf, size_t count) -{ - size_t nwritten = 0; - while (count > 0) { - int r = write(fd, buf, count); - - if (r < 0 && errno == EINTR) - continue; - if (r < 0) - return r; - if (r == 0) - return nwritten; - buf = (unsigned char *)buf + r; - count -= r; - nwritten += r; - } - return nwritten; -} - int __virFileReadAll(const char *path, int maxlen, diff --git a/src/util.h b/src/util.h index 7080ed0..23a016d 100644 --- a/src/util.h +++ b/src/util.h @@ -25,14 +25,14 @@ #define __VIR_UTIL_H__ #include "internal.h" +#include "util-lib.h" -int virExec(virConnectPtr conn, char **argv, int *retpid, int infd, int *outfd, int *errfd); -int virExecNonBlock(virConnectPtr conn, char **argv, int *retpid, int infd, int *outfd, int *errfd); +int virExec(virConnectPtr conn, char **argv, int *retpid, + int infd, int *outfd, int *errfd); +int virExecNonBlock(virConnectPtr conn, char **argv, int *retpid, + int infd, int *outfd, int *errfd); int virRun(virConnectPtr conn, char **argv, int *status); -int saferead(int fd, void *buf, size_t count); -ssize_t safewrite(int fd, const void *buf, size_t count); - int __virFileReadAll(const char *path, int maxlen, char **buf); -- 1.5.4.2.185.gf5f8

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[Libvir] Proposal: More script hooks for <interface type='ethernet'>
by Charles Duffy 25 Feb '08

25 Feb '08

I have a few issues with <interface type='ethernet'>: - The requirement that either (1) the tap device already exists and has a constant name, or (2) the tap device can be created by the current user without privilege escalation doesn't work for places where the user wants to - dynamically generate tap devices - ...but is running kvm without privileges to do so. (this is particularly likely now that write privileges to /dev/net/tap are not enough, and the user needs CAP_NET_ADMIN to create a tap device). Allowing a target script to be specified (which is responsible for gaining any privileges necessary) which runs *before* the tap device is opened and would resolve this. - A qemu-ifup script can be specified, but not a qemu-ifdown replacement. Before looking to use libvirt, I had kvm's invocation wrapped by a script which did appropriate privilege escalation (ifname=$(sudo tunctl -b -u $USER), with sudo configured with the NOPASSWORD flag for this request -- though plenty of other approaches are certainly possible). It would be ideal if more hooks were available... for instance: <interface type='ethernet'>  <target script='/usr/local/bin/make-me-a-tap-device'/>  <script path='/etc/qemu-ifup-mynet'/>  <script-down path='/etc/qemu-ifdown-mynet'/> </interface> Working around this means that I would need to preallocate the tap devices and assign them to specific VMs (boo! hiss!) or that (if I wrapped libvirt's invocation to have the tap device created just ahead of time and its name substituted into interface/@dev) 3rd-party libvirt-based management tools couldn't be used (which would defeat the point of switching to libvirt from my homegrown script collection in the first place). So -- does the proposed syntax extension look reasonable?

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[Libvir] Libparted history contribution
by Matt Davis 24 Feb '08

24 Feb '08

Hello, I am sending this email out to various programs that use libparted for partition table manipulation. If you are on the libparted devel list, you probably have caught word of this. I have implemented some functionality that allows parted to maintain a list of disk changes, allowing for a user to undo/redo changes before they are actually committed, or written, to disk. This "History" is a safety feature, and a library change vs usefulness might not be wanted by you all. I was just querying to see if such functionality, as an addition to libparted, would be welcomed? In any case, it might be useful for me to wrap it up into its own library, possibly something such as libparted-utilities or extras. While the changes I have implemented can exist outside of the library, I figured it might be something other projects might find useful. But making any library changes, especially when many well-known projects use such a library, is a serious decision. If this is a worthy change I would like to hear your feedback. Thanks -Matt

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[Libvir] Why QEMU?
by Anton Protopopov 23 Feb '08

23 Feb '08

Hi, all. When I executing virsh to connect to openvz I get the following: [root@localhost ~]# virsh -c openvz:///system libvir: QEMU error : cannot create bridge 'virbr0' : File exists Failed to autostart network 'default': cannot create bridge 'virbr0' : File existsWelcome to virsh, the virtualization interactive terminal. Type: 'help' for help with commands 'quit' to quit virsh # ... But I didn't want to connect to QEMU... Anton

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