Memory map

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The GameCube has one 24MB bank of 1T SRAM that is used for all code and data, spread across two external chips; there is also a chip containing 16MB of ARAM, which could be used for storing data (though it was not directly mapped into memory, instead only being accessible via DSP).

The Wii moves all 24MB of 1T-SRAM (referred to as MEM1) inside the Hollywood package, and adds an additional 64MB of GDDR3 RAM (MEM2). During normal operation, IOS reserves the upper 12-16MB of MEM2 for its own use; the rest can freely be used for code or data by running PPC code. MEM1 is slightly faster than MEM2. The Wii does not have the ARAM chip; instead, DSP can access MEM1 or MEM2. When using MIOS, the bottom 16 MB of MEM2 is used to emulate ARAM; the Tweezer Attack allowed accessing the rest of MEM2.

The IOS Heap range is usually 0x933E0000 – 0x93400000, as shown in registers 0x80003130(Start), 0x80003134(End). Pointers in this area are often passed back and forth between IOS and code running on Broadway. The top of MEM2 memory is allocated to IOS, and protected from access by some Hollywood Registers.

Start Address End Address Physical Address Physical End Address Size Description
0x80000000 0x817FFFFF 0x00000000 0x017FFFFF 24 MB MEM1 Memory (Cached)
0xC0000000 0xC17FFFFF 0x00000000 0x017FFFFF 24 MB MEM1 Memory (Uncached)
0x90000000 0x93FFFFFF 0x10000000 0x13FFFFFF 64 MB MEM2 Memory (Cached)
0xD0000000 0xD3FFFFFF 0x10000000 0x13FFFFFF 64 MB MEM2 Memory (Uncached)
0xCD000000 0xCD008000 0x0D000000 0x0D008000 32 KB Hollywood Registers (shared with Starlet)
Not Mapped Not Mapped 0x0C000000[check] 0x0C008003[check] 32 KB Broadway hardware registers
Not Mapped Not Mapped 0xFFF00100 0xFFF0013F 64 bytes EXI boot code mirror

Broadway / IOS Global Memory Locations

Address Size (Typical) Value Description
0x80000000 4 0x52535045 Game Code 'RSPE' (Wii Sports)
0x80000004 2 0x3031 (01) Maker code
0x80000006 1 0 Disc Number (multidisc games)
0x80000007 1 ? Disc Version
0x80000008 1 ? Disc Streaming flag
0x80000009 1 ? Disc Streaming buffer size
0x80000018 4 0x5D1C9EA3 Disc layout magic (Wii)
0x8000001C 4 0xC2339F3D Disc layout magic (GC)
0x80000020 4 0x0D15EA5E Nintendo Standard Boot Code.
0x80000024 4 0x00000001 Version (set by apploader)
0x80000028 4 0x01800000 Memory Size (Physical) 24MB
0x8000002C 4 0x00000023 Production Board Model
0x80000030 4 0x00000000 Arena Low
0x80000034 4 0x817FEC60 Arena High
0x80000038 4 0x817FEC60 Start of FST (varies in all games)
0x8000003C 4 0x00001394 Maximum FST Size (varies in all games)
0x80000040 4 ? Beginning of the DB global struct
0x80000044 4 ? DB marked exception mask
0x80000048 4 0x81340000 DB exception destination
0x8000004C 4 ? DB return address
0x80000060 0x24 OSDBIntegrator Debugger Hook Hook to be jumped to by debugged exceptions, but is disabled in production software. If nothing is written to it, SDK titles will write the 0x20 bytes of instructions here.
0x800000C0 4 ? Current OSContext instance (real mode)
0x800000C4 4 0xffffff00 User interrupt mask
0x800000C8 4 0 Revolution OS interrupt mask
0x800000CC 4 0 Value indicating the current video mode. 0 = NTSC, 1 = PAL, 2 = MPAL
0x800000D4 4 ? Current OSContext instance (translated mode)
0x800000D8 4 0 OSContext to save FPRs to (NULL if floating point mode hasn't been used since the last interrupt)
0x800000DC 4 ? Pointer to the earliest created OSThread
0x800000E0 4 ? Pointer to the most recently created OSThread
0x800000E4 4 ? Pointer to the current OSThread
0x800000EC 4 0x81800000 Dev Debugger Monitor Address (If present)
0x800000F0 4 0x01800000 Simulated Memory Size
0x800000F4 4 0x817FDF80 Pointer to data read from partition's bi2.bin, set by apploader, or the emulated bi2.bin created by the NAND Boot Program
0x800000F8 4 0x0E7BE2C0 Console Bus Speed
0x800000FC 4 0x2B73A840 Console CPU Speed
0x80000100 0x1700 Exception handlers (0x100 bytes reserved for each handler)
0x80001800 0x1800 Unused exception handler area, the SDK does not use or clear it. It is often used by homebrew to store persistent code here like Gecko OS's code handler, Bluebomb or The Homebrew Channel's reload stub, which libogc jumps to upon homebrew exit.
0x80003000 0x3c ? Exception vector area
0x80003040 4 ? __OSInterrupt table.
0x800030C0 8 ? EXI Probe start times, for both channels 0 and 1.
0x800030C8 4 ? Related to Nintendo's dynamic linking system (REL). Pointer to the first loaded REL file.
0x800030CC 4 ? Related to Nintendo's dynamic linking system (REL). Pointer to the last loaded REL file.
0x800030D0 4 0 Pointer to a REL module name table, or 0. Added to the name offset in each REL file.
0x800030D8 8 0x005498F053407000 System time, measured as time since January 1st 2000 in units of 1/40500000th of a second.
0x800030E4 2 ? __OSPADButton. Apploader puts button state of GCN port 4 at game start here for Gamecube NR disc support
0x800030E6 2 ? DVD Device Code Address
0x800030E8 4 ? Debug-related info
0x800030F0 4 0x00000000 DOL Execute Parameters
0x80003100 4 ? Physical MEM1 size
0x80003104 4 ? Simulated MEM1 size
0x8000310C 4 ? MEM1 Arena Start (start of usable memory by the game)
0x80003110 4 ? MEM1 Arena End (end of usable memory by the game)
0x80003118 4 0x04000000 Physical MEM2 size. (0x3118-0x314C are set by IOS upon reload.)
0x8000311C 4 0x04000000 Simulated MEM2 size.
0x80003120 4 0x93400000 End of MEM2 addressable to PPC.
0x80003124 4 0x90000800 Usable MEM2 Start (start of usable memory by the game)
0x80003128 4 0x933E0000 Usable MEM2 End (end of usable memory by the game)
0x80003130 4 0x933E0000 IOS IPC Buffer Start
0x80003134 4 0x93400000 IOS IPC Buffer End
0x80003138 4 0x00000011 Hollywood Version
0x80003140 4 0x00090204 IOS version (090204 = IOS9, v2.4)
0x80003144 4 0x00062507 IOS Build Date (62507 = 06/25/07 = June 25, 2007)
0x80003148 4 0x93600000 IOS Reserved Heap Start
0x8000314C 4 0x93620000 IOS Reserved Heap End
0x80003158 4 0x0000FF16 GDDR Vendor Code
0x8000315C 1 0x80 During the boot process, u32 0x315c is first set to 0xdeadbeef by IOS in the boot_ppc syscall. The value is set to 0x80 by the NAND Boot Program to indicate that it was loaded by the boot program (and probably 0x81 by apploaders)
0x8000315D 1 0? "Enable legacy DI" mode? 0x81 = false, anything else means true (though typically set to 0x80). Required to be set when loading Gamecube apploader.
0x8000315E 2 0x0113 "Devkit boot program version", written to by the system menu. The value carries over to disc games. 0x0113 appears to mean v1.13.
0x80003160 4 0x00000000 Init semaphore (1-2 main() waits for this to clear)
0x80003164 4 0x00000000 GC (MIOS) mode flag, set to 1 by boot2 when MIOS triggers a shutdown; the System Menu reads this and turns off the console if it is set to 1 and state.dat is set appropriately.
0x80003180 4 0x52535045 Game ID 'RSPE' Wii Sports ID. If these 4 bytes don't match the ID at 80000000, WC24 mode in games is disabled.
0x80003184 1 0x80 Application type. 0x80 for disc games, 0x81 for channels.
0x80003186 1 0x00 Application type 2. Appears to be set to the when a game loads a channel (e.g. Mario Kart Wii loading the region select menu will result in this being 0x80 from the disc and the main application type being 0x81, or the Wii Fit channel transitioning to the Wii Fit disc will result in this being 0x81 and the main type being 0x80).
0x80003188 4 0x00351011 Minimum IOS version (2 bytes for the major version, 2 bytes for the title version)
0x8000318C 4 0x00000000 Title Booted from NAND (Launch Code)
0x80003190 4 0x00000000 Title Booted from NAND (Return Code)
0x80003194 4 0x00000000 While reading a disc, the system menu reads the first partition table (0x20 bytes from 0x00040020) and stores a pointer to the data partition entry. When launching the disc game, it copies the partition type to 0x3194. The partition type for data partitions is 0, so typically this location always has 0.
0x80003198 4 data partition offset While reading a disc, the system menu reads the first partition table (0x20 bytes from 0x00040020) and stores a pointer to the data partition entry. When launching the disc game, it copies the partition offset to 0x3198.
0x8000319C 1 0x80 Set by the apploader to 0x80 for single-layer discs and 0x81 for dual-layer discs (determined by whether 0x7ed40000 is the value at offset 0x30 in the partition's bi2.bin; it seems that that value is 0 for single-layer discs). Early titles' apploaders do not set it at all, leaving the value as 0. This controls the out-of-bounds Error #001 read for titles that do make such a read: they try to read at 0x7ed40000 for dual-layer discs and 0x460a0000 for single-layer discs.
0x80003400 0x400 "BS1" boot code
0x80003F00 0x132c100 (~19.2MB) Standard application executable area
0x81330000 0x4d0000 (~4.8MB) Loader executable area, also used by a NAND Boot Program

By convention, applications should use the 0x80003F00 – 0x81330000 area for executable code and data loaded as part of their ELF/DOL, while loaders should use from 0x81330000 onwards. Applications can use the loader area and MEM2 as data work space once they are running, but they should restrict the sections contained in the DOL or ELF to the executable area only, since MEM2 is reserved as work area for the loader at that time. To preserve "return to loader" functionality, applications should never use the 0x80001800-0x80003000 area.