Xen on PowerPC
Xen is an Open Source Hypervisor thats allows multiple instances of a modified operating system to run on a single physical system. Xen was designed for the x86 architecture, which lacked CPU extensions necessary to minimize hypervisor impact to OS code and system performance. The PowerPC architecture, as embodied in IBM's PowerPC 970 implementation, added hypervisor-enabling features to the processor architecture to reduce the performance overhead of IBM's enterprise hypervisor. These extensions differ in philosophy from the design points reached by the Xen project. This paper describes some of the architectural differences between the two environments, and some of the challenges faced in porting the Xen hypervisor to the PowerPC architecture. Particular difficulties include Xen's memory-sharing model, its concept of address spaces, and our attempt to support the IBM enterprise hypervisor binary interface so that current PowerPC Linux kernels can run without modification.
Hollis Blanchard learned computer architecture and operating systems through PowerPC Linux, and has been developing for the Linux kernel for six years, four of those while working for IBM.
Jimi has been programming computers since he was able to find a Radio Shack store manager that would let him play with the TRS-80 that no one ever wanted to buy. He currently is a member IBM's TJ Watson Research Laboratory where he tinkers with Hypervisors, Processors, K42 Research OS, Linux, Simulators, and Tool-chains. Prior to IBM he worked on other OSes for other companies.