Understanding the LoadProhibited Error

Oct 13, 2025 by wbrum.org 4 views

Introduction

When working with FreeRTOS, a popular real-time operating system (RTOS) for microcontrollers, developers may encounter various errors and stack traces. One such error is the "LoadProhibited" stack trace error, which can be frustrating and challenging to resolve. In this article, we will delve into the causes and solutions of the LoadProhibited stack trace error in FreeRTOS, providing a comprehensive guide for developers to overcome this issue.

Understanding the LoadProhibited Error

The LoadProhibited error occurs when the FreeRTOS kernel attempts to access a memory location that is not allowed. This can happen due to various reasons, including:

Memory corruption: When memory is corrupted, the kernel may attempt to access invalid memory locations, leading to the LoadProhibited error.
Stack overflow: A stack overflow occurs when the stack size is exceeded, causing the kernel to access memory locations outside the stack, resulting in the LoadProhibited error.
Incorrect memory allocation: Incorrect memory allocation can lead to memory corruption, causing the LoadProhibited error.

Analyzing the Stack Trace

To diagnose the LoadProhibited error, it is essential to analyze the stack trace. The stack trace provides valuable information about the sequence of function calls that led to the error. By examining the stack trace, developers can identify the source of the error and take corrective action.

Example Stack Trace

The following is an example stack trace for the LoadProhibited error:

LoadProhibited (0x4000d3c0)
  at 0x4000d3c0: vPortYieldWithTimeOut (0x4000d3c0)
  at 0x4000d3c0: vTaskDelete (0x4000d3c0)
  at 0x4000d3c0: vTaskDelete (0x4000d3c0)
  at 0x4000d3c0: vTaskDelete (0x4000d3c0)
  ...

Causes of the LoadProhibited Error

Based on the stack trace, the causes of the LoadProhibited error can be identified as:

Recursive function calls: The vTaskDelete function is called recursively, leading to a stack overflow.
Incorrect memory allocation: The vPortYieldWithTimeOut function attempts to access memory locations outside the stack, resulting in the LoadProhibited error.

Solutions to the LoadProhibited Error

To resolve the LoadProhibited error, the following solutions can be applied:

Prevent recursive function calls: Ensure that functions do not call themselves recursively, as this can lead to a stack overflow.
Correct memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.
Increase stack size: If the stack size is exceeded, increase the stack size to prevent stack overflows.

Best Practices for Preventing LoadProhibited Errors

To prevent LoadProhibited errors, follow these best practices:

Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.

Conclusion

In conclusion, the LoadProhibited stack trace error in FreeRTOS can be caused by various factors, including memory corruption, stack overflow, and incorrect memory allocation. By analyzing the stack trace and applying the solutions outlined in this article, developers can overcome the LoadProhibited error and ensure the reliability and stability of their FreeRTOS-based applications.

Additional Resources

For further information on FreeRTOS and the LoadProhibited error, refer to the following resources:

FreeRTOS documentation: The official FreeRTOS documentation provides detailed information on the kernel and its features.
FreeRTOS forums: The FreeRTOS forums offer a platform for developers to discuss FreeRTOS-related issues and share knowledge.
FreeRTOS examples: The FreeRTOS examples provide code examples and demonstrations of FreeRTOS features and applications.

Code Example

The following code example demonstrates how to prevent recursive function calls and correct memory allocation:

#include <FreeRTOS.h>
#include <task.h>
void vTaskDelete(void *pvParameter)
{
// Prevent recursive function calls
if (pvParameter == NULL)
{
return;
}
// Correct memory allocation
void *pvStack = pvPortMalloc(1024);
if (pvStack == NULL)
{
    return;
}

// Perform task deletion
vTaskDelete(pvStack);

}
int main(void)
{
// Create a task
xTaskCreate(vTaskDelete, "Task Delete", 1024, NULL, 1, NULL);
// Start the FreeRTOS scheduler
vTaskStartScheduler();

return 0;

}

Q: What is the LoadProhibited error in FreeRTOS?

A: The LoadProhibited error is a stack trace error that occurs when the FreeRTOS kernel attempts to access a memory location that is not allowed. This can happen due to various reasons, including memory corruption, stack overflow, and incorrect memory allocation.

Q: What are the common causes of the LoadProhibited error?

A: The common causes of the LoadProhibited error include:

Recursive function calls: When functions call themselves recursively, it can lead to a stack overflow and the LoadProhibited error.
Incorrect memory allocation: When memory is allocated incorrectly, it can lead to memory corruption and the LoadProhibited error.
Stack overflow: When the stack size is exceeded, it can lead to a stack overflow and the LoadProhibited error.

Q: How can I prevent the LoadProhibited error?

A: To prevent the LoadProhibited error, follow these best practices:

Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.

Q: What is the difference between a stack overflow and a LoadProhibited error?

A: A stack overflow occurs when the stack size is exceeded, causing the kernel to access memory locations outside the stack. A LoadProhibited error occurs when the kernel attempts to access a memory location that is not allowed, which can be due to various reasons including memory corruption, stack overflow, and incorrect memory allocation.

Q: How can I diagnose the LoadProhibited error?

A: To diagnose the LoadProhibited error, analyze the stack trace. The stack trace provides valuable information about the sequence of function calls that led to the error. By examining the stack trace, developers can identify the source of the error and take corrective action.

Q: What are the symptoms of the LoadProhibited error?

A: The symptoms of the LoadProhibited error include:

Kernel panic: The kernel may panic and crash, resulting in a stack trace error.
System freeze: The system may freeze, preventing any further execution.
Data corruption: Data may become corrupted, leading to unpredictable behavior.

Q: Can the LoadProhibited error be prevented entirely?

A: While it is not possible to prevent the LoadProhibited error entirely, following best practices and implementing stack overflow protection can significantly reduce the likelihood of the error occurring.

Q: What are the consequences of ignoring the LoadProhibited error?

A: Ignoring the LoadProhibited error can lead to:

System crashes: The system may crash, resulting in data loss and unpredictable behavior.
Data corruption: Data may become corrupted, leading to unpredictable behavior.
Security vulnerabilities: Ignoring the LoadProhibited error can lead to security vulnerabilities, allowing malicious actors to exploit the system.

Q: How can I troubleshoot the LoadProhibited error?

A: To troubleshoot the LoadProhibited error, follow these steps:

Analyze the stack trace: Examine the stack trace to identify the source of the error.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.

Q: What are the best practices for preventing the LoadProhibited error?

A: The best practices for preventing the LoadProhibited error include:

Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.
Follow coding standards: Follow coding standards and best practices to prevent memory corruption and incorrect memory allocation.

Q: Can the LoadProhibited error be fixed after it occurs?

A: While it is possible to fix the LoadProhibited error after it occurs, it is often more challenging and time-consuming than preventing the error in the first place. To fix the error, follow these steps:

Analyze the stack trace: Examine the stack trace to identify the source of the error.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.

Q: What are the long-term consequences of ignoring the LoadProhibited error?

A: Ignoring the LoadProhibited error can lead to long-term consequences, including:

System instability: The system may become unstable, leading to unpredictable behavior.
Data corruption: Data may become corrupted, leading to unpredictable behavior.
Security vulnerabilities: Ignoring the LoadProhibited error can lead to security vulnerabilities, allowing malicious actors to exploit the system.

Q: Can the LoadProhibited error be prevented in embedded systems?

A: Yes, the LoadProhibited error can be prevented in embedded systems by following best practices and implementing stack overflow protection. Additionally, using a memory debugger can help detect memory corruption and incorrect memory allocation.

Q: What are the best practices for preventing the LoadProhibited error in embedded systems?

A: The best practices for preventing the LoadProhibited error in embedded systems include:

Use a memory debugger: Utilize a memory debugger to detect memory corruption and incorrect memory allocation.
Implement stack overflow protection: Implement stack overflow protection to prevent stack overflows and LoadProhibited errors.
Verify memory allocation: Verify that memory is allocated correctly and that the kernel is not attempting to access memory locations outside the stack.
Follow coding standards: Follow coding standards and best practices to prevent memory corruption and incorrect memory allocation.