Depending on when in a system’s lifecycle these issues are publicized a hardware revision might not occur. While it may be possible to mitigate some of these bugs in software, the issues can only be properly fixed via a hardware revision. Early code execution can be an easy way dump the entirety of a boot ROM. The 3DS’s “sighax” or the Wii’s “trucha” bug are two notable examples. The downside of more complex boot ROMs is that they often contain security vulnerabilities that can allow code execution early in the boot process. More complex boot ROMs may be multiple stages, with the earlier stages being progressively more difficult to dump. Such is the case for the Game Boy, which completely removes all traces of the boot ROM from memory before handing any control over to the game. On some systems accessing the boot ROM from software is simply not possible without hardware modifications. However, these protections make it difficult to dump the boot ROMs. But due to the complexity of these boot ROMs many emulators actually require them to be provided to run at all. Thus many emulators that use a boot ROM require users to obtain a copy separately from the emulator.įurther, many systems contain protections to prevent the boot ROM from being directly accessed or dumped.
Since the boot ROM is actual code and not a system design, it is potentially copyrightable and leads to concerns with distribution. There are advantages and disadvantages to both approaches, but the most notable disadvantage to the boot ROM approach is that it necessitates having a copy of the boot ROM itself. But from an accuracy-focused, low-level emulation perspective, starting the emulation from a clean slate and run the boot ROM directly is often more desirable. One approach is to initialize the emulated state to reflect the state of an already booted system. When emulating a system, there are two ways to emulate the boot process.
This is usually referred to as the boot ROM. On many systems, especially on specialized systems such as video game consoles, there is a fixed set of initialization routines for the boot process stored in read-only memory inside the system. Once these tasks, generally referred to as booting, are complete, control passes over to the main system. A computer must perform a series of initialization tasks when turned on before it becomes ready for use.
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