On Thu, Feb 21, 2008 at 02:36:10PM +0000, Daniel P. Berrange wrote:
On Thu, Feb 21, 2008 at 09:26:38AM -0500, Daniel Veillard wrote:
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,
I think it is worthwhile - the 'default to Xen' behavious is a major cause of pain for people initially using libvirt, particularly since KVM is becoming the defacto standard for Linux platforms. I'd see the following levels of customization:
- If a non-NULL URI is passed in virConnectOpen, use that - Else if LIBVIRT_DEFAULT_URI is set use that URI - Else probe each registered driver in order until one succeeds
For the latter I think we could add a 'probe' method to the internal driver API table. Then we can just call 'probe' on each driver in turn until we find one which is available on the system.
Yup, that's even better than ad-hoc attempt at detecting, it really should go in the driver.
At the same time it could be worth having a public API to 'detect drivers' which will call probe for each driver and return a list of all drivers which are available. This allows an app to easily ask libvirt what it supports - because long term we'll definitely get hosts supporting many drivers at once. We can also advertise this list of supported drivers using the Avahi mDNS broadcasts we do from the remote daemon.
That can be done in a second step, less urgent IMHO but useful too, Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/