Memory Services



The memory services is responsible for managing physical memory, GDT descriptors and LDT descriptors. It manages physical memory via a table called the PAM.

Page Allocation Map

This table has a word entry for each physical page. The entry normally contains the descriptor number for the code that owns the page. Exceptions to this are:

If the entry contains a descriptor number, the lower 2 bits contain the type of allocation:

System Page Directory

This is the address of a page used for a normal page directory (see intel's programmers guides). It maps common memory (first 1Gb of physical memory) to the linear space. The memory manager can use this as a template when creating address spaces for applications. It is also used by system tasks (drivers, etc).

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Copyright 1998, Brendan Trotter