Patent ID: 8041923
Filing Date: 2011-10-18
Classification: G06F

Abstract:
1. A computer program product for performing a load page table entry address function in a computer system of a machine architecture, said computer system configured to translate a virtual address into a translated address of a block of data in main storage, the computer system having a hierarchy of translation tables for translation of said virtual address, said load page table entry function defined for said machine architecture, the computer program product comprising: a storage medium readable by said computer system, said computer readable medium storing instructions for performing: obtaining a machine instruction defined for said machine architecture and containing an opcode for a Load Page Table Entry Address instruction, said machine instruction further comprising an M field, a first field identifying a first general register and a second field identifying a second general register; and executing said machine instruction comprising: obtaining from said second register a virtual address to be translated; based on said M field, determining an initial address of a hierarchy of address translation tables, said hierarchy of address translation tables comprising a segment table; based on said initial address, performing dynamic address translation of said virtual address to obtain a segment table entry address of a segment table entry of said segment table; responsive to an enhanced dynamic address translation (eDAT) facility being enabled wherein said segment table entry comprises a format control field, wherein a not-enabled value of the format control field indicates the segment table entry consists of a first set of fields and an address of a page table, wherein an enabled value of the format control field indicates the segment table entry consists of the first set of fields, a second set of fields and an absolute address of a large block of main storage, determining whether the format control field consists of the enabled value or the not-enabled value; and responsive to determining the format control field in said segment table entry has an enabled value, saving said segment table entry address in said first general register.