Memory Organization
Memory zones
- DMA memory: first 16MB of main memory
- Kernel attempts to make memory available in this region for legacy hardware
- Normal memory: between 16MB and 896MB on the IA-32 architecture
- Stores user data and most kernel data
- High memory: > 896MB on the IA-32 architecture
- Contains memory that the kernel does not permanently map to its address space
Bounce buffer
- Allocates low memory temporarily for I/O
- Data is “bounced” to high memory after I/O completes