Host Virtual DLAT Entries
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
A design having a hardware assist which allows the creation and usage of host virtual directory look-aside table (DLAT) entries while in a start interpretive execution (SIE) mode results in a performance gain for guest virtual DLAT trap in a system that runs under VM/XA. The address check boundary (ACB) bit in the DLAT is defined as the host bit 1 to distinguish between host entries and guest entries. After the first DLAT trap 2 in SIE the host addresses for the guest segment table entries and page table entries would be resolved. For succeeding references a virtual read is executed to fetch the guest entries. A storage microword-readhost is defined to use a host bit from the DLAT to provide a DLAT miss branch 3 instead of a DLAT miss trap.