Virtual Memory

The ARM926EJ-S MMU is used to map NOR, SDRAM and peripherals in memory.

Virtual memory is split into 1MB sections.

The Translation Table Base Register (CP15 register c2) contains the address of an array of 4096 words, each one describes a section.

The MMU allows both reads and writes on all mentioned sections, the others will trigger an exception for any access.

0x00000000-0x000FFFFF (1MB) - NOR

boot1 ?

• Physical address : 0xA4000000-0xA40FFFFF
• not cached, not buffered

0x10000000-0x11EFFFFF (31MB) - SDRAM

First 31MB of RAM

• Physical address : 0x10000000-0x11EFFFFF
• write-back cache

0x11F00000-0x11FFFFFF (1MB) - SDRAM

Last 1MB of RAM

• Physical address : 0x11F00000-0x11FFFFFF
• not cached, not buffered

0x12000000-0x17FFFFFF (96MB)

Unknown

• Physical address : 0x12000000-0x17FFFFFF
• not cached, not buffered

0x18000000-0x180FFFFF (1MB) - alias of SDRAM

• Physical address : 0x11E00000-0x11EFFFFF (alias of 0x11E00000-0x11EFFFFF virtual address)
• write-back cache

0x8FF00000-0x901FFFFF (3MB) - Memory-mapped I/O ports

• Physical address : 0x8FF000000-0x901FFFFF
• not cached, not buffered

0xA0000000-0xA00FFFFF (1MB)

I/O ?

• Physical address : 0xA0000000-0xA00FFFFF
• not cached, not buffered

0xA4000000-0xA40FFFFF (1MB) - alias of NOR

• Physical address : 0xA4000000-0xA40FFFFF (alias of 0x00000000-0x000FFFFF virtual address)
• not cached, not buffered

0xA9000000-0xA90FFFFF (1MB)

I/O ?

• Physical address : 0xA9000000-0xA90FFFFF
• not cached, not buffered

0xAC000000-0xAC0FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xAC000000-0xAC0FFFFF
• not cached, not buffered

0xB0000000-0xB00FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xB0000000-0xB00FFFFF
• not cached, not buffered

0xB4000000-0xB40FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xB4000000-0xB40FFFFF
• not cached, not buffered

0xB8000000-0xB80FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xB8000000-0xB80FFFFF
• not cached, not buffered

0xBC000000-0xBC0FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xBC000000-0xBC0FFFFF
• not cached, not buffered

0xC0000000-0xC00FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xC0000000-0xC00FFFFF
• not cached, not buffered

0xC4000000-0xC40FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xC4000000-0xC40FFFFF
• not cached, not buffered

0xC8000000-0xC80FFFFF (1MB)

I/O ?

• Physical address : 0xC8000000-0xC80FFFFF
• not cached, not buffered

0xCC000000-0xCC0FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xCC000000-0xCC0FFFFF
• not cached, not buffered

0xDC000000-0xDC0FFFFF (1MB) - Memory-mapped I/O ports

• Physical address : 0xDC000000-0xDC0FFFFF
• not cached, not buffered