Memory Management System Redesign

I won’t lie, memory management is the most frustrating thing in OS design for me. It takes the most time and debugging it is nevertheless exhausting. I have, however, redesigned it to be more generic than before and relax much more arch. dependent code.

The New Design

Physical Memory Management

AquilaOS uses zoned buddy memory allocation technique, which is used in Linux and many *BSDs. Currently we only have two zones ZONE_DMA and ZONE_NORMAL which have identical functionality to that found in Linux.

Virtual Memory Management

In the new design, the kernel deals with a one level of paging while the archticture handles the intermediate paging levels. Now each process has defined memory mapped regions wich is either lazily loaded from file, lazily allocated or lazily copied on fork. This allows for very efficient memory use (even the stack is allocated on demand). And finally, AquilaOS has no more memory leaks.