Patent ID: 8117417

Claim:
A computer program product for translation of a virtual address into a translated address of a block of data in main storage in a computer system of a machine architecture, the computer program product comprising: a computer storage medium readable by said computer system, said computer storage medium storing instructions for performing: obtaining a virtual address of a desired block of main storage to be translated; obtaining an initial origin address of a translation table of a hierarchy of translation tables, said hierarchy of translation tables comprising a segment table; based on the obtained initial origin address and said virtual address, obtaining a segment table entry from said segment table; in response to an enhanced dynamic address translation (eDAT) facility being enabled, determining whether a format control field in said segment table entry has an enabled value; and in response to said format control field having the enabled value, performing: obtaining from said segment table entry an absolute address of a large block of main storage comprising a plurality of 4 Kilobyte (K byte) blocks, each 4 (K byte) block within said large block of main storage having an associated storage key, each storage key comprising a change bit, wherein a translated address of the desired block within said large block of main storage comprises a combination of said absolute address and a page index portion of said virtual address, the combination identifying a desired 4K byte block of main storage; determining whether a change recording override field in said segment table entry has an enabled value; performing a store operation associated with said virtual address to said 4K byte block; and in response to said change recording override field being disabled, performing: setting a first change bit of a first storage key associated with said 4K byte block to 1, to indicate that said 4K byte block has been modified.