On 02/10/2010 07:23 PM, Ed Swierk wrote:
On Wed, Feb 10, 2010 at 1:02 AM, Daniel P. Berrange <berrange@redhat.com> wrote:
Mostly what Alex already said :-)
The libvirt APIs are split into several functional areas
- virDomain - guest management - virInterface - host network interface configuration - virStorage - storage manangement - virNetwork - virtual networking
The goal is that an app should be able to accomplish all its virtualization management tasks without needing any other remote access to the host via SSH or other systems. Many of the APIs for those areas I mention above require knowledge of what physical devices are present on the machine. For example, assigning a PCI or USB device to a guests requires that you know what PCI / USB devices the host has. Setting up a storage pool requires knowing what disks are available. Configuring network interfaces requires knowing what NICs are available, etc. So 'virNodeDev' APIs provide the missing link that lets you discover the information about a host that you need in order to use the other APIs.
Thanks, Daniel and Alex, that helps a lot.
I'm still not clear about the purpose of the node device XML format, and the nodedev-create virsh command. What does it mean to "create a device" on a node, if the node device info is gathered via udev or hal from the actual hardware? Is this to fill in gaps in udev's or hal's knowledge of the hardware?
The nodedev-create function is currently only used to create NPIV virtual adapters. It's true in general that 'creating' a node device doesn't really make sense, since a node device is actually physical hardware, hence the very limited application ATM. Similarly nodedev-destroy destroys NPIV virtual adapters. - Cole