Recompiling My Custom Kernel And My .config Is Set To Old Config Every Time

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Introduction

Recompiling a custom kernel can be a daunting task, especially when encountering issues that seem to defy explanation. One such issue is when the .config file is set to its old configuration every time, despite making changes to the kernel source code. In this article, we will delve into the world of kernel compilation and explore the possible reasons behind this phenomenon.

Understanding the Kernel Compilation Process

Before we dive into the issue at hand, it's essential to understand the kernel compilation process. The kernel compilation process involves several stages, including:

  1. Configuring the kernel: This is the first step in the kernel compilation process, where the user selects the desired kernel configuration using the .config file.
  2. Compiling the kernel: Once the kernel configuration is set, the kernel source code is compiled into a binary image.
  3. Installing the kernel: The compiled kernel binary is then installed on the system, replacing the existing kernel.

The Issue of .config Being Set to Old Config Every Time

Now that we have a basic understanding of the kernel compilation process, let's focus on the issue at hand. When recompiling a custom kernel, it's not uncommon to encounter issues where the .config file is set to its old configuration every time. This can be frustrating, especially when you've made changes to the kernel source code and expect the new configuration to be reflected in the compiled kernel.

Possible Reasons Behind the Issue

There are several possible reasons behind this issue, including:

  • Kernel configuration cache: The kernel configuration cache is a temporary file that stores the kernel configuration settings. If the cache is not properly cleared, it can cause the .config file to be set to its old configuration every time.
  • Dirty kernel source code: If the kernel source code is not properly cleaned up after making changes, it can cause the .config file to be set to its old configuration every time.
  • Incorrect kernel configuration file: If the kernel configuration file is not properly updated, it can cause the .config file to be set to its old configuration every time.

Troubleshooting the Issue

To troubleshoot the issue, follow these steps:

  1. Clear the kernel configuration cache: Run the command make mrproper to clear the kernel configuration cache.
  2. Clean up the kernel source code: Run the command make clean to clean up the kernel source code.
  3. Update the kernel configuration file: Run the command make oldconfig to update the kernel configuration file.
  4. Recompile the kernel: Run the command make to recompile the kernel.

Conclusion

Recompiling a custom kernel can be a complex process, and encountering issues like the .config file being set to its old configuration every time can be frustrating. However, by understanding the kernel compilation process and troubleshooting the issue, you can overcome this problem and successfully recompile your custom kernel.

Additional Tips and Tricks

Here are some additional tips and tricks to help you overcome the issue:

  • Use the make command with the -j option: The -j option allows you to specify the number of parallel jobs to run during the compilation process. This can significantly speed up the compilation process.
  • Use the make command with the O option: The O option allows you to specify the output directory for the compiled kernel binary.
  • Use the make command with the C option: The C option allows you to specify the number of clean passes to run during the compilation process.

Common Issues and Solutions

Here are some common issues and solutions to help you overcome the issue:

  • Issue: Kernel compilation fails due to missing dependencies: Solution: Run the command make -j to specify the number of parallel jobs to run during the compilation process.
  • Issue: Kernel compilation fails due to incorrect kernel configuration file: Solution: Run the command make oldconfig to update the kernel configuration file.
  • Issue: Kernel compilation fails due to dirty kernel source code: Solution: Run the command make clean to clean up the kernel source code.

Kernel Compilation Best Practices

Here are some kernel compilation best practices to help you overcome the issue:

  • Use the make command with the -j option: The -j option allows you to specify the number of parallel jobs to run during the compilation process.
  • Use the make command with the O option: The O option allows you to specify the output directory for the compiled kernel binary.
  • Use the make command with the C option: The C option allows you to specify the number of clean passes to run during the compilation process.
  • Clear the kernel configuration cache: Run the command make mrproper to clear the kernel configuration cache.
  • Clean up the kernel source code: Run the command make clean to clean up the kernel source code.

Conclusion

Q: What is the kernel configuration cache, and how can I clear it?

A: The kernel configuration cache is a temporary file that stores the kernel configuration settings. You can clear it by running the command make mrproper. This will delete the kernel configuration cache and force the kernel configuration to be re-read from the .config file.

Q: Why is my kernel configuration file not being updated?

A: There are several reasons why your kernel configuration file may not be being updated. One possible reason is that the kernel configuration cache is not being cleared properly. Try running the command make mrproper to clear the cache and then re-run the kernel configuration process.

Q: How can I troubleshoot issues with my kernel compilation?

A: To troubleshoot issues with your kernel compilation, try the following steps:

  1. Clear the kernel configuration cache: Run the command make mrproper to clear the kernel configuration cache.
  2. Clean up the kernel source code: Run the command make clean to clean up the kernel source code.
  3. Update the kernel configuration file: Run the command make oldconfig to update the kernel configuration file.
  4. Recompile the kernel: Run the command make to recompile the kernel.

Q: What is the difference between make and make oldconfig?

A: The make command is used to compile the kernel, while the make oldconfig command is used to update the kernel configuration file. If you want to recompile the kernel with the same configuration settings, use the make command. If you want to update the kernel configuration file, use the make oldconfig command.

Q: How can I speed up the kernel compilation process?

A: To speed up the kernel compilation process, try the following:

  1. Use the -j option: The -j option allows you to specify the number of parallel jobs to run during the compilation process. This can significantly speed up the compilation process.
  2. Use the O option: The O option allows you to specify the output directory for the compiled kernel binary.
  3. Use the C option: The C option allows you to specify the number of clean passes to run during the compilation process.

Q: What are some common issues that can occur during kernel compilation?

A: Some common issues that can occur during kernel compilation include:

  • Kernel compilation fails due to missing dependencies: Try running the command make -j to specify the number of parallel jobs to run during the compilation process.
  • Kernel compilation fails due to incorrect kernel configuration file: Try running the command make oldconfig to update the kernel configuration file.
  • Kernel compilation fails due to dirty kernel source code: Try running the command make clean to clean up the kernel source code.

Q: How can I ensure that my kernel configuration file is up-to-date?

A: To ensure that your kernel configuration file is up-to-date, try the following:

  1. Clear the kernel configuration cache: Run the command make mrproper to clear the kernel configuration cache.
  2. Clean up the kernel source code: Run the command make clean to clean up the kernel source code.
  3. Update the kernel configuration file: Run the command make oldconfig to update the kernel configuration file.

Q: What are some kernel compilation best practices that I should follow?

A: Some kernel compilation best practices that you should follow include:

  • Use the -j option: The -j option allows you to specify the number of parallel jobs to run during the compilation process.
  • Use the O option: The O option allows you to specify the output directory for the compiled kernel binary.
  • Use the C option: The C option allows you to specify the number of clean passes to run during the compilation process.
  • Clear the kernel configuration cache: Run the command make mrproper to clear the kernel configuration cache.
  • Clean up the kernel source code: Run the command make clean to clean up the kernel source code.

Conclusion

Recompiling a custom kernel can be a complex process, and encountering issues like the .config file being set to its old configuration every time can be frustrating. However, by understanding the kernel compilation process, troubleshooting the issue, and following kernel compilation best practices, you can overcome this problem and successfully recompile your custom kernel.