QEMU is a generic and open source machine emulator and virtualizer.

When used as a machine emulator, QEMU can run OSes and programs made for 
one machine (e.g. an ARM board) on a different machine (e.g. your own PC). 
By using dynamic translation, it achieves very good performances.

qemu-kvm achieves near native performances by leveraging the kvm-kmod
modules and executing the guest code directly on the host CPU.
Slackware provides pre-built 32/64 bit x86 kvm-kmod modules or you can
build different versions with the kvm-kmod package.
qemu-kvm code has been merged back into qemu since version 1.3.0.

By default, this script builds only the x86 and arm emulation targets
for qemu; if you prefer to build all supported targets, do this:

  TARGETS=all ./qemu.SlackBuild

We patch the installed udev rules to require membership in "users" 
group instead of a custom "kvm" group to uses /dev/kvm.  If you prefer
something different, then run the build script like this:
  
  KVMGROUP=group ./qemu.SlackBuild

Don't forget to load the 'kvm-intel' or 'kvm-amd' module (depending on 
your processor) prior to launching qemu-system-x86_64 with kvm enabled.

spice and usbredir are optional dependencies.