Hardware/Main Memory

From WiiBrew
Jump to: navigation, search
Start Address End Address Physical Address Size Description
0x00000000 0x017FFFFF 0x00000000 24 MB MEM1 Memory
0x10000000 0x13FFFFFF 0x10000000 64 MB MEM2 Memory
0x0D000000 0x0D000000 Hardware Registers
0x0D400000 0x0D400000 Internal SRAM
0x0D800000 0x0D800000 Hardware Registers
0xFFF00000 0xFFFFFFFF Internal SRAM (mirror)

Hollywood I/O registers are at 0x0D80xxxx (Starlet private) and 0x0D00xxxx (shared with the Broadway). That is to say, the contents of 0x0D80xxxx are selectively mirrored to 0x0D0xxxxx. The Broadway "sees" 0x0D00xxxx when it tries to access 0x0D80xxxx (that address bit is forced to zero). This changes depending on some of the registers (e.g. when MIOS is active). Starlet private peripherals, however, live in 0x0D0yxxxx for y!=0 and the Broadway can't see them.

The GDDR3 is at 0x10000000, 64MB of it; a configurable range is exclusive for use by the Starlet (IOS reserves the top 12MB), the rest is shared with the Broadway.

0x0D0xxxxx may be an AMBA AHB bus.

The Starlet internal SRAM (96kB) mappings are weird (someone wikify this):

SRAM and BOOT0 map into two main canonical areas (with tons of mirrors):
 - 0x0d400000 - 0x0d41ffff
 - 0xfffe0000 - 0xffffffff

Mirrors of note:

0xfff00000-0xfff1ffff is equivalent to 0x0d400000-0x0d41ffff.
This is actually mirrored until 0xfffe0000 (or 0xffff0000 if you count half a mirroring block), where the mapping starts to differ.

BOOT0 runs from 0xffff0000 and loads BOOT1 into 0x0d400000, with HOLLYWOOD[0x60]&0x20 off
BOOT1 runs from 0xfff00000 and 0x0d400000, with HOLLYWOOD[0x60]&0x20 off
(BOOT1 seems to be compiled at 0x0d400000 but is called at 0xfff00000, so the program flow continuously switches between them as it goes through jump tables or back out through the stack and relative jumps)
BOOT2LOADER runs from MEM1, switches HOLLYWOOD[0x60]&0x20 on, then loads BOOT2
BOOT2/IOS runs from 0xffff0000, switches off BOOT0, then uses 0xfffe0000 as data RAM too, with HOLLYWOOD[0x60]&0x20 on

These are the maps:

--- BOOT0 enabled ---

 HOLLYWOOD[0x60]&0x20 clear     HOLLYWOOD[0x60]&0x20 set

 fff00000                       fff00000
 0d400000     fffe0000          0d400000     fffe0000
+---------+  +---------+       +---------+  +---------+  +00000
|         |  |         |       |         |  |         |
|         |  |         |       |         |  |         |
|         |  |         |       |         |  |         |
| SRAM A  |  | SRAM A  |       |         |  |  BOOT0  |  +08000
|         |  |         |       |         |  |   x8    |
|         |  |         |       |         |  |         |
|         |  |         |       |         |  |         |
+---------+  +---------+       |  BOOT0  |  +---------+  +10000
|         |  |         |       |   x16   |  |         |
| SRAM B  |  |         |       |         |  |         |
|         |  |         |       |         |  |         |
+---------+  |  BOOT0  |       |         |  | SRAM A  |  +18000
|         |  |   x8    |       |         |  |         |
|  JUNK   |  |         |       |         |  |         |
|         |  |         |       |         |  |         |
+---------+  +---------+       +---------+  +---------+  +20000

--- BOOT0 disabled ---

 HOLLYWOOD[0x60]&0x20 clear     HOLLYWOOD[0x60]&0x20 set

 fff00000                       fff00000
 0d400000     fffe0000          0d400000     fffe0000
+---------+  +---------+       +---------+  +---------+  +00000
|         |  |         |       |         |  |         |
|         |  |         |       | SRAM B  |  | SRAM B  |
|         |  |         |       |         |  |         |
| SRAM A  |  | SRAM A  |       +---------+  +---------+  +08000
|         |  |         |       |         |  |         |
|         |  |         |       |  JUNK   |  |  JUNK   |
|         |  |         |       |         |  |         |
+---------+  +---------+       +---------+  +---------+  +10000
|         |  |         |       |         |  |         |
| SRAM B  |  | SRAM B  |       |         |  |         |
|         |  |         |       |         |  |         |
+---------+  +---------+       | SRAM A  |  | SRAM A  |  +18000
|         |  |         |       |         |  |         |
|  JUNK   |  | JUNK    |       |         |  |         |
|         |  |         |       |         |  |         |
+---------+  +---------+       +---------+  +---------+  +20000