|Jolitz Heritage ]||
Berkeley UNIX Virtual Memory System Strategy
The current Berkeley UNIX virtual memory management subsystem was originally designed for use with a VAX, and as such has no support for page directories. For that matter, the 386 doesn't know of such VAX concepts as P0 and P1 address spaces for instruction/data and stack nor of pagetable-length registers. Currently, these are simulated in 386BSD. However, work is underway to revise the entire virtual memory system to permit more generalized operation over all supported Berkeley UNIX platforms, now that the demands of each platform have been made obvious.
Portions of the VAX were simulated by employing code, written by Mike Hibler at the University of Utah, which supports the 68030 paging memory management. Because the 386 code is so similar, we used a conditional compilation that shares 68030 and 386 versions interchangeably -- an odd couple indeed.
Copyrightę1994 Willaim & Lynne Jolitz