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Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
2841e6756d
libvirt was able to set the host_mtu option when an MTU was explicitly given in the interface config (with <mtu size='n'/>), set the MTU of a libvirt network in the network config (with the same named subelement), and would automatically set the MTU of any tap device to the MTU of the network. This patch ties that all together (for networks based on tap devices and either Linux host bridges or OVS bridges) by learning the MTU of the network (i.e. the bridge) during qemuInterfaceBridgeConnect(), and returning that value so that it can then be passed to qemuBuildNicDevStr(); qemuBuildNicDevStr() then sets host_mtu in the interface's commandline options. The result is that a higher MTU for all guests connecting to a particular network will be plumbed top to bottom by simply changing the MTU of the network (in libvirt's config for libvirt-managed networks, or directly on the bridge device for simple host bridges or OVS bridges managed outside of libvirt). One question I have about this - it occurred to me that in the case of migrating a guest from a host with an older libvirt to one with a newer libvirt, the guest may have *not* had the host_mtu option on the older machine, but *will* have it on the newer machine. I'm curious if this could lead to incompatibilities between source and destination (I guess it all depends on whether or not the setting of host_mtu has a practical effect on a guest that is already running - Maxime?) Likewise, we could run into problems when migrating from a newer libvirt to older libvirt - The guest would have been told of the higher MTU on the newer libvirt, then migrated to a host that didn't understand <mtu size='blah'/>. (If this really is a problem, it would be a problem with or without the current patch). |
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| .gnulib@94386a1366 | ||
| build-aux | ||
| daemon | ||
| docs | ||
| examples | ||
| gnulib | ||
| include/libvirt | ||
| m4 | ||
| po | ||
| src | ||
| tests | ||
| tools | ||
| .ctags | ||
| .dir-locals.el | ||
| .gitignore | ||
| .gitmodules | ||
| .mailmap | ||
| AUTHORS.in | ||
| autobuild.sh | ||
| autogen.sh | ||
| bootstrap | ||
| bootstrap.conf | ||
| cfg.mk | ||
| ChangeLog-old | ||
| config-post.h | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LESSER | ||
| HACKING | ||
| libvirt-admin.pc.in | ||
| libvirt-lxc.pc.in | ||
| libvirt-qemu.pc.in | ||
| libvirt.pc.in | ||
| libvirt.spec.in | ||
| Makefile.am | ||
| Makefile.nonreentrant | ||
| mingw-libvirt.spec.in | ||
| README | ||
| README-hacking | ||
| run.in | ||
| TODO | ||
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>