[2012-03-12]

From running openSuSE 12, we see virt-manager being used to give an easy gui to the KVM system.
This runs well.  Back on Gentoo, a simple emerge on libvirt and virt-manager gave clean installation 
but not an immediately working application.  

Sun's [Oracle's] "VirtualBox" on the other hand is also Free, (though needing kernel modules
outside the default kernel tree, which could sometimes cause trouble), and gives a nicer interface
and apparently more functionality, e.g. usb[-2.0].  In one way, the principle of kvm, using existing 
methods such as 'br' for standard network bridging etc, might seem more sensible, efficient and 
"the unix way";  but the vmware-like method of virtualbox, putting all this functionality into its 
own modules, has certain advantages of easy one-step setup without interfering with other parts of 
the system.

Just load the virtualbox modules:
 	for f in vbox{drv,netadp,netflt}; do modprobe $f ; done 
and run the VirtualBox command.  


2012-04-04.

Now have been trying VirtualBox on the normal desktop, and comparing with virt-manager.

Gentoo emerge output (including options) for relevant packages:

app-emulation/qemu-kvm-1.0-r3  USE="aio alsa curl ncurses opengl sasl sdl threads vhost-net xattr -bluetooth -brltty -debug -fdt -pulseaudio -qemu-ifup (-rbd) -smartcard -spice -static -test -tls -usbredir -vde -xen" QEMU_SOFTMMU_TARGETS="x86_64 -arm -cris -i386 -m68k -microblaze -mips -mips64 -mips64el -mipsel -ppc -ppc64 -ppcemb -sh4 -sh4eb -sparc -sparc64" QEMU_USER_TARGETS="-alpha -arm -armeb -cris -i386 -m68k -microblaze -mips -mipsel -ppc -ppc64 -ppc64abi32 -sh4 -sh4eb -sparc -sparc32plus -sparc64 -x86_64" 0 kB
app-emulation/libvirt-0.9.10-r4  USE="libvirtd lxc nfs nls policykit python qemu sasl udev virtualbox -avahi -caps -debug -iscsi -lvm -macvtap -numa -openvz -parted -pcap -phyp (-selinux) -uml -virt-network -xen" 0 kB
app-emulation/virt-manager-0.9.1  USE="policykit sasl -gnome-keyring -spice" 0 kB


app-emulation/virtualbox-4.1.8  USE="additions alsa java opengl pam python qt4 sdk vnc -doc -extensions -headless -pulseaudio -vboxwebsrv" 0 kB
app-emulation/virtualbox-modules-4.1.8  USE="-pax_kernel" 0 kB



--- libvirt, virt-manager

virt-manager is a GTK front-end to "libvirt".  libvirt, in turn, is a general library 
for managing virtualisation: it can deal with QEMU (including the KVM [kernel virtual machine]
form that we're considering) and with Xen and VirtualBox (and others?).

To run with KVM, only some real 


--- VirtualBox

This is a single "package".  It has several kernel modules (see above), all outside the normal
kernel tree but nevertheless open and GPL2, like the rest of virtualbox.  No trouble compiling
the modules so far, even on newest gentoo kernels.

Images default to the ~/.VirtualBox/Machines directory, and everything is very obvious from 
the GUI.  The GUI uses QT rather than GTK, so it's vastly more visually pleasing, responsive, and 
better set up for re-finding already used paths.