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On Linux each network device *can* (but not necessarily *does*) have an attribute called phys_port_id which can be read from the file of that name in the netdev's sysfs directory. The examples I've seen have been a many-digit hexadecimal number (as an ASCII string). This value can be useful when a single PCI device is associated with multiple netdevs (e.g a dual port Mellanox SR-IOV NIC - this card has a single PCI Physical Function (PF), and that PF has two netdevs associated with it (the "net" subdirectory of the PF in sysfs has two links rather than the usual single link to a netdev directory). Each of the PF netdevs has a different phys_port_id. The Virtual Functions (VF) are similar - the PF (a PCI device) has "n" VFs (also each of these is a PCI device), each VF has two netdevs, and each of the VF netdevs points back to the VF PCI device (with the "device" entry in its sysfs directory) as well as having a phys_port_id matching the PF netdev it is associated with. virNetDevGetPhysPortID() simply attempts to read the phys_port_id for the given netdev and return it to the caller. If this particular netdev driver doesn't support phys_port_id, it returns NULL (*not* a NULL-terminated string, but a NULL pointer) but still counts it as a success.
Libvirt API for virtualization
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.
For some of these hypervisors, it provides a stateful management daemon which runs on the virtualization host allowing access to the API both by non-privileged local users and remote users.
Layered packages provide bindings of the libvirt C API into other languages including Python, Perl, PHP, Go, Java, OCaml, as well as mappings into object systems such as GObject, CIM and SNMP.
Further information about the libvirt project can be found on the website:
License
The libvirt C API is distributed under the terms of GNU Lesser General
Public License, version 2.1 (or later). Some parts of the code that are
not part of the C library may have the more restrictive GNU General
Public License, version 2.1 (or later). See the files COPYING.LESSER
and COPYING for full license terms & conditions.
Installation
Libvirt uses the GNU Autotools build system, so in general can be built and installed with the usual commands. For example, to build in a manner that is suitable for installing as root, use:
$ ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var
$ make
$ sudo make install
While to build & install as an unprivileged user
$ ./configure --prefix=$HOME/usr
$ make
$ make install
The libvirt code relies on a large number of 3rd party libraries. These will
be detected during execution of the configure script and a summary printed
which lists any missing (optional) dependencies.
Contributing
The libvirt project welcomes contributions in many ways. For most components the best way to contribute is to send patches to the primary development mailing list. Further guidance on this can be found on the website:
https://libvirt.org/contribute.html
Contact
The libvirt project has two primary mailing lists:
- libvirt-users@redhat.com (for user discussions)
- libvir-list@redhat.com (for development only)
Further details on contacting the project are available on the website: