December 2011
Intermediate to advanced
485 pages
15h 47m
English
Content preview from OS X and iOS Kernel ProgrammingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Types of Memory
The kernel deals with multiple types of memory, so understanding the difference is key to implementing a successful driver or kernel extension.
The types of memory can be categorized as:
- CPU physical address
- bus physical address
- user and kernel virtual addresses
In addition to the three types of memory addresses, the amount of addressable memory differs between architectures and can be from 32-bit to 64-bit. Memory may also be ordered differently depending on the architecture and can be of little or big endian.
The following sections will discuss the importance and usage of each type of memory as it applies to kernel programming.
CPU Physical Address
A physical address refers to the addressing system used by the CPU to access ...