Institute for the Development of Emerging Architectures, L.l.c.

Gary N Hammon

Koichi Yamada

Rajiv Gupta

Jonathan Kent Ross

William R Bryg

Stephen G Burger

James O Hays

A method and apparatus pre-validate regions in a virtual addressing scheme by storing both the virtual region number (VRN) bits and region identifiers (RIDs) in translation lookaside buffer (TLB) entries. By storing both the VRN bits and RIDs in TLB entries, the region registers can be bypassed when performing most TLB accesses, thereby removing region registers the critical path of the TLB look-up process and enhancing system performance. A TLB in accordance with the present invention includes entries having a valid field, a region pre-validation valid (rpV) field, a virtual region number (VRN) field, a virtual page number (VPN) field, a region identifier (RID) field, a protection and access attributes field, and a physical page number (PPN) field. In addition, a set of region registers contains the RIDs that are active at any given time. When a virtual-to-physical entry is established for a page in a region having an RID stored in a region register, the RID and VRN are stored in the appropriate fields of the TLB entry. In addition, the valid field is set and the rpV field is set to indicate that the TLB entry contains an active VRN-to-RID mapping, thereby pre-validating the region. When a physical address is translated into a virtual address, a VRN and a VPN are extracted from the virtual address and provided to the TLB. The TLB is searched to find an entry having a set valid field, a set rpV field, and VRN and VPN fields containing entries matching the VRN and VPN extracted from the virtual address. If such an entry is found, the protection and access attributes field is used to determine whether the requested access is allowed. If the requested access is allowed, the PPN from the PPN field of the TLB entry is combined with an offset from the virtual address to produce a physical address that is used to complete the memory access.

Growing community of inventors

Campbell, CA, United States of America

Gary N Hammon