Executables (CORE.GT3/CORE.GT4)

Starting from GT3, the game is split between two executables:

• SCES_517.19 (or any other game code) - Bootstrap executable
• CORE.GT3/CORE.GT4/CORE.TT - Main executable.

Note

Some older GT4-engine builds such as GT4 First Preview or Tourist Trophy Demo does not use a bootstrap executable.

Bootstrap executable

The bootstrap executable serves as a way to launch and verify the CORE/main executable through different sources (in order):

1. HostSource - HOST - Using host, host:/tmp/CORE.GT4
2. CardSource - MCARD 0 - Using memory card 1
3. CardSource - MCARD 1 - Using memory card 2
4. DiskSource - DISK - Using CORE.GT4 at the root of the disk

Here is a flowchart of the boot process after a suitable CORE.GT4 has been located.

Boot process flowchart (click to expand)

graph TD
  Start[Start] --> OpenCore[Attempt to open CORE from various sources] --> CRCCheck;
  CRCCheck{CRC Matches?} ---->|No| Failed;
  CRCCheck --> GT4OCheck

  GT4OCheck{Is GT4O?} ----> Decrypt[Decrypt CORE] ----> Decompress
  GT4OCheck --> Decompress

  Decompress[Decompress CORE] --> ReadHeader[Read header]
  ReadHeader --> HeaderHashCheck

  HeaderHashCheck{Computed hash matches with header?} ---->|No| Failed;
  HeaderHashCheck --> OverlapCheck

  OverlapCheck{Defined segments overlap?} ---->|Yes| Failed;
  OverlapCheck --> ValidEntrypointCheck

  ValidEntrypointCheck{Is valid entrypoint address?} ---->|No| Failed;
  ValidEntrypointCheck --> END

  END(["✔️ Ready to go, pass arguments and entry to ExecPS2"])
  style END fill:#00BB00

  Failed["❌ Failed, invalid Image"]
  style Failed fill:#CC0000

```

---

CORE executable

This is the main executable after the bootstrap has successfully validated it.

Refer to the CORE format for how it is laid out more in detail.

Tip

PDTools.GT4ElfBuilderTool can process a CORE file to an ELF file for easier use in IDA or Ghidra.