Various technologies and techniques are disclosed for providing software accessible metadata on a cache of a central processing unit. The metadata can include at least some bits for each virtual address, at least some bits for each cache line, and at least some bits for the cache overall. An instruction set architecture on the central processing unit is provided that includes additional instructions for interacting with the metadata. New side effects that are introduced into an operation of the central processing unit by a presence of the metadata and the additional instructions. The metadata can be accessed by at least one software program to facilitate an operation of the software program.