15.5. Example Address Map¶
This sample address map (for an Intel processor-based system) describes a machine that has 128 MiB of RAM, 640 KiB of base memory and 127 MiB of extended memory. The base memory has 639 KiB available for the user and 1 KiB for an extended BIOS data area. A 4-MiB Linear Frame Buffer (LFB) is based at 12 MiB. The memory hole created by the chip set is from 8 MiB to 16 MiB. Memory-mapped APIC devices are in the system. The I/O Unit is at FEC00000 and the Local Unit is at FEE00000. The system BIOS is remapped to 1 GB-64 KiB.
The 639-KiB endpoint of the first memory range is also the base memory size reported in the BIOS data segment at 40:13. The following table shows the memory map of a typical system.
Base (Hex) |
Length |
Type |
Description |
|---|---|---|---|
0000 0000 |
639 KiB |
AddressRangeMemory |
Available Base memory. Typically the same value as is returned using the INT 12 function. |
0009 FC00 |
1 KiB |
AddressRangeReserved |
Memory reserved for use by the BIOS(s). This area typically includes the Extended BIOS data area. |
000F 0000 |
64 KiB |
AddressRangeReserved |
System BIOS |
0010 0000 |
7 MiB |
AddressRangeMemory |
Extended memory, which is not limited to the 64-MiB address range. |
0080 0000 |
4 MiB |
AddressRangeReserved |
Chip set memory hole required to support the LFB mapping at 12 MiB. |
0100 0000 |
60 MiB |
AddressRangeMemory |
Baseboard RAM relocated above a chip set memory hole. |
04C0 0000 |
60 MiB |
AddressRangePersistentMemory |
Persistent memory that has non-volatile attributes located in this region. |
FEC0 0000 |
4 KiB |
AddressRangeReserved |
I/O APIC memory mapped I/O at FEC00000. |
FEE0 0000 |
4 KiB |
AddressRangeReserved |
Local APIC memory mapped I/O at FEE00000. |
FFFF 0000 |
64 KiB |
AddressRangeReserved |
Remapped System BIOS at end of address space. |