StackGhost: sparc/sparc64-specific buffer overflow protection stackghost.cerias.purdue.edu/stackghost.pdf Register window architectures: Sparc v6/v7/v8 and UltraSparc Each time a function call is made, the latter 3 sets "rotate" The processor has a limited set of registers on-chip.. so cpu traps to SPILL & FILL handlers in the kernel to store registers to memory, or refetch registers from memory -- on the stack.