DOL File Format – Memory Map

Where a program’s sections go

Introduction

The addresses in a DOL are the virtual addresses the PowerPC uses. Main memory appears twice: at 0x80000000 through the cache, and at 0xC0000000 without it; the hardware registers sit at 0xCC000000 and above, and the Wii adds a second memory and the Hollywood registers. The tables follow the Yet Another GameCube Documentation (YAGCD, chapter 4) and WiiBrew “Memory map”, read through page summaries (our words).

Address ranges

FromToNameWhat it is
0x800000000x817FFFFFMEM1, cachedThe GameCube’s 24 MiB of main memory (physical 0x00000000 to 0x017FFFFF) and the Wii’s MEM1. Where a DOL is loaded.
0xC00000000xC17FFFFFMEM1, uncachedThe same memory, not cached.
0x900000000x93FFFFFFMEM2, cachedWii only: 64 MiB (physical 0x10000000 to 0x13FFFFFF).
0xD00000000xD3FFFFFFMEM2, uncachedWii only: the same 64 MiB, not cached.
0xC8000000—EFBThe embedded framebuffer of the graphics chip: YAGCD gives 2 MiB, WiiBrew 3 MiB (to 0xC8300000).
0xCC0000000xCC008003Hardware registersThe memory-mapped registers; see hardware registers. WiiBrew marks the end of the range as unchecked.
0xCD0000000xCD008000Hollywood registersWii only: shared with the Starlet processor.
0xE00000000xE0003FFFLocked cache16 KiB of the L2 cache, usable as memory (YAGCD: “L2 Cache”; the locked cache instruction is dcbz_l).
0xFFF00000—IPLThe boot ROM, mapped here at start-up (YAGCD: 1 MiB; WiiBrew also lists a 64-byte EXI boot code mirror at 0xFFF00100).

The viewer accepts a DOL section in the first four rows. The uncached and cached addresses of one physical memory are treated as the same memory when it looks for overlaps.

Low memory: the OS globals

The first 256 bytes of main memory hold values the system and the disc fill in before a program runs. The table lists what YAGCD (section 4.2.1, “OS globals”) names at these addresses. The names starting OS_ are labels this viewer uses; the page gives descriptions.

AddressSizeLabelMeaning
0x800000004OS_GAME_CODEThe game code, four characters.
0x800000042OS_COMPANYThe company code.
0x800000061OS_DISC_NUMBERThe disc number.
0x800000071OS_VERSIONThe game’s version.
0x800000081OS_STREAMINGAudio streaming flag.
0x800000091OS_STREAM_BUFFER_SIZEAudio streaming buffer size.
0x8000001C4OS_DVD_MAGICThe DVD magic word, 0xC2339F3D.
0x800000204OS_BOOT_MAGICThe boot magic word: 0x0D15EA5E means a normal boot.
0x800000244OS_BOOT_VERSIONVersion, usually 1.
0x800000284OS_MEMORY_SIZEPhysical memory size: 0x01800000 is 24 MiB.
0x8000002C4OS_CONSOLE_TYPEConsole type.
0x800000304OS_ARENA_LOThe low end of the memory arena.
0x800000344OS_ARENA_HIThe high end of the memory arena.
0x800000384OS_FST_LOCATIONWhere the file system table is in memory.
0x8000003C4OS_FST_MAX_LENGTHThe maximum length of the file system table.
0x800000404OS_DEBUGGER_FLAGThe debugger flag.
0x800000CC4OS_TV_MODEThe video mode.
0x800000F84OS_BUS_CLOCKThe bus clock speed.
0x800000FC4OS_CPU_CLOCKThe CPU clock speed.

The rest of the 256 bytes is not listed here. In a DOL’s disassembly, a load or store whose address is built with lis r3, 0x8000 and lands on one of these is noted with the label; the same offsets through the uncached window 0xC0000000 are named too.

Not described

Known, not yet covered

  • Reference: the BATs and page tables that create the windows above, the rest of the OS globals (YAGCD lists more, and the fetch tool’s summary may not have given them all), the memory the IOS reserves on the Wii (the upper 12 to 16 MiB of MEM2 per WiiBrew) and the ARAM.

Unknown

  • The end of the Broadway register range: WiiBrew marks 0xCC008003 as unchecked.

Links

Reference