Memory

This document describes how the kernel organizes and manages the memory.

Pages

TODO

Isolation

Each process has its own 64-bit address space, preventing it from accessing other processes' data. The memory is made of pages, which must be either be allocated or mapped using virtual memory segments.

Abstract memory segments

An abstract memory segment (AMS) is an identifier which refers to a segment of memory which doesn't actually exist. To be used, they must be mapped in a process' memory to be accessed like regular memory. The kernel then intercepts all memory accesses to these mappings and handle them, depending on their nature which cover three cases:

• Mapping existing memory pages to others, or sharing them with other processes ;
• Mapping a device's memory into the process' own memory space ;
• Making a virtual memory space handled by signals

An AMS can then be mapped at multiple places in a process' memory, or shared with other processes. The kernel handles mappings to get optimal performances and reduce the number of memory accesses as much as possible.