Unlike VMware, which builds a complete virtual machine, Xen is a hypervisor, a layer that
doesn??™t quite go that far. This technology vastly improves the performance of guest operating
systems in tests to nearly native performance. This requires a special Xen version of
each supported OS kernel. openSUSE implements this is by using the standard kernel for a
standard installation, putting the Xen kernel into /boot, and then using the grub bootloader
application to boot to either the Xen kernel or the standard kernel.
Xen developers have ported several open source kernels, including the 2.4 and 2.6 Linux
kernels, NetBSD Unix, FreeBSD Unix, and the Plan9 OS, so you can use Xen today to run
several Linux distributions side by side with a copy of FreeBSD to spare. This might be
Xen: The Future of Virtualization? 239
11
entertaining for some users, but is especially useful to programmers hoping to solve distribution-
related problems. It??™s also useful when testing pre-release versions of distributions
like openSUSE.
The key question for many users is whether Windows will join the list of supported OSs
at some point.
Pages:
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534