MediEvil CUSA11227: Emulation Failure On MacOS

Introduction

In this article, we delve into the emulation status of MediEvil (CUSA11227) on the shadPS4 emulator, specifically focusing on an error encountered on macOS. Emulation, the process of mimicking one system on another, can be complex, and this report highlights a specific hurdle in running MediEvil on a macOS environment using shadPS4. We'll dissect the error, the setup used, and what this means for the broader emulation community. Understanding these issues is crucial for the continued development and refinement of emulators, allowing more players to experience classic games on modern systems. This article serves as a comprehensive overview for both enthusiasts and developers interested in the intricacies of PlayStation 4 emulation.

Checklist and Setup

Before diving into the specifics of the error, let’s review the checklist followed to ensure a consistent and reproducible testing environment. This meticulous approach is essential in the emulation community to accurately identify and address issues. The checklist includes several critical steps, each designed to eliminate potential variables that could lead to inaccurate results. By adhering to these guidelines, we can ensure that the error reported is directly related to the emulation process and not influenced by external factors. This systematic approach not only helps in troubleshooting but also in fostering trust within the community regarding the accuracy of the findings.

Key Steps in the Checklist

• Latest Major Release: The testing was conducted on the latest major release of shadPS4 (version 0.12.5), ensuring that the results reflect the most stable and up-to-date version of the emulator. This is crucial because nightly builds, while containing the newest features, may also introduce instability. Using a major release provides a solid foundation for testing and reporting.
• Officially Released Game: The game in question, MediEvil, is an officially released PlayStation 4 title. This is important because homebrew or unofficial games may not adhere to the same standards and could introduce unique issues not representative of the emulator's performance with commercial titles. Testing with official releases ensures that the emulator is evaluated under typical usage conditions.
• No Duplicate Issues: A thorough check was performed to confirm that no other issues had been opened for the same game and operating system combination. This prevents redundancy and helps maintain a clean and organized issue tracking system. It also ensures that developers can focus on unique problems without wasting time on previously reported issues.
• Owned Game Copy: The game dump was created from a legally owned copy of MediEvil. This is a fundamental ethical consideration in the emulation community. Supporting developers by purchasing their games is crucial for the industry's health. Emulation should be seen as a way to preserve and enjoy games, not as a means of piracy.
• Unmodified Game Dump: The game dump was unmodified, meaning no patches were applied, and the game was not repackaged into a FPKG format. Modifying the game files can introduce unpredictable behavior, making it difficult to determine whether an error is due to the emulator or the modifications. Keeping the game dump in its original state ensures a clean testing environment.
• Firmware Libraries: The PlayStation 4's firmware libraries were correctly dumped and placed in the shadPS4 'sys_modules' folder. These libraries are essential for the emulator to function correctly, as they contain the system-level code required to run PlayStation 4 games. Ensuring these files are present and correctly placed is a critical step in the setup process.
• Logging Type: The logging type was set to “sync” rather than “async.” Synchronous logging ensures that all log messages are written in real-time, providing a more accurate and complete record of the emulation process. This is vital for debugging, as it allows developers to trace the execution flow and identify the exact point where an error occurs.
• Default Settings: No manual settings were enabled that would alter emulation behavior. This includes settings such as “isPS4Pro,” “isDevKit,” and “Vblank Frequency.” Sticking to default settings provides a baseline for testing, ensuring that the results are representative of the emulator's standard performance.

Game Information

• Game Name: MediEvil
• Game Serial: CUSA11227
• Game Version: 1.02

These details provide specific identification of the game being emulated, which is essential for accurate reporting and issue tracking. Knowing the game version is particularly important, as different versions may have different behaviors or issues. This information helps developers narrow down the scope of the problem and potentially identify version-specific bugs.

Emulator Version and Operating System

• Used Emulator Version: 0.12.5
• Operating System: macOS

Specifying the emulator version and operating system is crucial for reproducibility. Errors can be specific to certain versions of the emulator or operating systems, so this information helps developers replicate the issue and identify its root cause. It also allows users to determine if the error they are experiencing is a known issue with a specific configuration.

Current Status: Nothing

The “Current Status: Nothing” indicates that the game did not progress beyond the initial loading phase. This is a critical piece of information, as it suggests that the error occurs very early in the emulation process, potentially before the game's main code even begins to execute. Understanding when the failure occurs helps developers focus their efforts on the relevant parts of the emulator's codebase.

Error Details

Error Message

The primary error encountered is:

[Debug] <Critical> memory.cpp:433 operator(): Assertion Failed!
Attempted to access invalid address 0x4000000000

This error message is highly informative, providing several key insights into the nature of the problem. Let's break it down:

• [Debug] : This indicates that the error is a critical issue encountered during a debug build of the emulator. Critical errors are severe and typically prevent the emulator from functioning correctly.
• memory.cpp:433 operator(): This pinpoints the location of the error within the emulator's codebase. Specifically, it occurred in the memory.cpp file, on line 433, within the operator() function. This suggests the error is related to memory management, which is a common area for issues in emulation.
• Assertion Failed!: An assertion failure indicates that a condition expected to be true was actually false. Assertions are used in programming to catch unexpected states and are often used during development to help identify bugs.
• Attempted to access invalid address 0x4000000000: This is the most crucial part of the error message. It reveals that the emulator attempted to access a memory address (0x4000000000) that is considered invalid. Invalid memory access is a common cause of crashes and errors in software, as it can lead to reading or writing to memory that is not allocated or protected.

Interpretation

This error strongly suggests a memory management issue within the shadPS4 emulator when running MediEvil on macOS. The emulator is attempting to access a memory address that is outside the allowed range, leading to the assertion failure and subsequent crash. This could be due to a variety of factors, such as:

• Incorrect Memory Mapping: The emulator may be incorrectly mapping the PlayStation 4's memory space onto the host system's memory space.
• Buffer Overflow: A buffer overflow could be occurring, where data is written beyond the bounds of an allocated memory buffer, leading to corruption and invalid memory access.
• Pointer Errors: There may be errors in the use of pointers, such as dereferencing a null or dangling pointer.
• Memory Leaks: While less likely to cause an immediate crash, memory leaks can eventually lead to memory exhaustion and other issues.

Description: Black Window and Closure

The user described the experience as seeing a black window for a split second before the emulator closes. This behavior aligns with the memory access error. A black window often indicates that the application has started but has not yet rendered anything to the screen, or that the rendering process has failed. The immediate closure suggests a critical error that the emulator cannot recover from, such as the memory access violation reported.

Screenshots: No Response

The lack of screenshots is not surprising given the nature of the error. Since the emulator crashes almost immediately, there is likely no opportunity to capture a meaningful screenshot. This further reinforces the idea that the issue occurs very early in the game's execution.

Log File Analysis

The provided log file, shad_log.txt, is a valuable resource for further analysis. A detailed examination of the log file can provide additional context and potentially pinpoint the exact sequence of events leading to the error. Log files often contain a wealth of information, including:

• Initialization Sequences: The log may show the emulator's initialization process, including the loading of libraries and the setup of memory regions.
• System Calls: System calls made by the game can be logged, providing insight into the game's interaction with the emulated operating system.
• Error Messages: In addition to the primary error message, the log may contain other related error messages or warnings that shed light on the issue.
• Call Stack: A call stack, if available, can show the sequence of function calls that led to the error, helping developers trace the execution flow.

By analyzing the log file, developers can gain a deeper understanding of the error and identify potential areas for improvement in the emulator's code.

Conclusion and Next Steps

The error report for MediEvil (CUSA11227) on shadPS4 running macOS highlights a critical memory access violation. The emulator attempts to access an invalid memory address, leading to an assertion failure and subsequent crash. This issue occurs very early in the game's execution, preventing it from progressing beyond the initial loading phase. The detailed error message and the provided log file offer valuable information for developers to investigate and address the problem.

Potential Next Steps

1. Log File Analysis: Developers should thoroughly analyze the shad_log.txt file to identify the exact sequence of events leading to the error.
2. Code Review: A review of the memory.cpp file, particularly around line 433, is warranted to identify potential memory management issues.
3. Debugging: Using debugging tools, developers can step through the emulator's code and inspect memory contents to pinpoint the source of the invalid memory access.
4. Testing on Other Platforms: Testing MediEvil on other operating systems and hardware configurations may help determine if the issue is specific to macOS or more general.
5. Community Collaboration: Sharing the findings and collaborating with the wider emulation community can lead to new insights and potential solutions.

Addressing this memory access violation is crucial for improving the compatibility and stability of shadPS4. By systematically investigating the error and implementing appropriate fixes, developers can enhance the emulator's performance and allow more users to enjoy PlayStation 4 games on their systems.

External resources for learning more about game emulation and debugging:

• Emulation General Wiki: Emulation General Wiki

By providing detailed reports and actively participating in the emulation community, users play a vital role in the ongoing development and improvement of emulators like shadPS4. This collaborative effort ensures that classic games are preserved and made accessible to future generations.