Xen Dom0, are we making progress?

[Matthew Dillon]

:Virtual kernels are a cool idea, but I (and I believe practically anyone
:using FreeBSD for non-development work) would much rather see a Xen-like
:functionality (to be precise: ability to run foreign kernels and
:Windows; qemu is too slow) than just a variation of the native kernel.

    There is certainly a functionality there that people will find useful,
    but you also have to realize that Xen involves two or more distinct
    operating systems which will multiply the number of bugs you have to
    deal with and create major compatibility issues with the underlying
    hardware, making it less then reliable.

    Really only the disk and network I/O can be made reliably compatible
    in a Xen installation.  Making sound cards, video capture cards, 
    encryption cards, graphics engines, and many other hardware features
    work well with the guest operating system will not only be difficult,
    but it will also be virtually unmaintainable in that environment over
    the long term.  Good luck getting anything more then basic application
    functionality out of it.

    For example, you would have no problem running pure network applications
    such as web and mail servers on the guest operating system, but the
    moment you delve outside of that box and into sound and high quality 
    (or high performance) video, things won't be so rosy.

    I don't see much of an advantage in having multi-OS hardware 
    virtualization for any serious deployment.  It would be interesting and
    useful on a personal desktop, at least within the scope of the limited
    hardware compatibility, but at the same time it will also lock you into
    software and OS combinations that aren't likely to extend into the
    future, and which will be a complete an utter nightmare to maintain.
    Any failure at all could lead to a completely unrecoverable system.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>