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You're reading from  Linux Device Driver Development - Second Edition

Product typeBook
Published inApr 2022
PublisherPackt
ISBN-139781803240060
Edition2nd Edition
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Author (1)
John Madieu
John Madieu
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John Madieu

John Madieu is an embedded Linux and kernel engineer living in Paris, France. His main activities consist of developing device drivers and Board Support Packages (BSPs) for companies in domains such as IoT, automation, transport, healthcare, energy, and the military. John is the founder and chief consultant at LABCSMART, a company that provides training and services for embedded Linux and Linux kernel engineering. He is an open source and embedded systems enthusiast, convinced that it is only by sharing knowledge that we can learn more. He is passionate about boxing, which he practiced for 6 years professionally, and continues to channel this passion through training sessions that he provides voluntarily.
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Handling module parameters

Similar to a user program, a kernel module can accept arguments from the command line. This allows us to dynamically change the behavior of the module according to the given parameters, which can help a developer not have to indefinitely change/compile the module during a test/debug session. In order to set this up, we should first declare the variables that will hold the values of command-line arguments and use the module_param() macro on each of these. The macro is defined in include/linux/moduleparam.h (this should be included in the code too – #include <linux/moduleparam.h>) as follows:

module_param(name, type, perm);

This macro contains the following elements:

  • name: The name of the variable used as the parameter.
  • type: The parameter's type (bool, charp, byte, short, ushort, int, uint, long, and ulong), where charp stands for character pointer.
  • perm: This represents the /sys/module/<module>/parameters/<...
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Linux Device Driver Development - Second Edition
Published in: Apr 2022Publisher: PacktISBN-13: 9781803240060

Author (1)

author image
John Madieu

John Madieu is an embedded Linux and kernel engineer living in Paris, France. His main activities consist of developing device drivers and Board Support Packages (BSPs) for companies in domains such as IoT, automation, transport, healthcare, energy, and the military. John is the founder and chief consultant at LABCSMART, a company that provides training and services for embedded Linux and Linux kernel engineering. He is an open source and embedded systems enthusiast, convinced that it is only by sharing knowledge that we can learn more. He is passionate about boxing, which he practiced for 6 years professionally, and continues to channel this passion through training sessions that he provides voluntarily.
Read more about John Madieu