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Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

You're reading from   Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization Create user-kernel interfaces, work with peripheral I/O, and handle hardware interrupts

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Product type Paperback
Published in Mar 2021
Publisher Packt
ISBN-13 9781801079518
Length 452 pages
Edition 1st Edition
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Author (1):
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Kaiwan N. Billimoria Kaiwan N. Billimoria
Author Profile Icon Kaiwan N. Billimoria
Kaiwan N. Billimoria
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Table of Contents (11) Chapters Close

Preface 1. Section 1: Character Device Driver Basics
2. Writing a Simple misc Character Device Driver FREE CHAPTER 3. User-Kernel Communication Pathways 4. Working with Hardware I/O Memory 5. Handling Hardware Interrupts 6. Working with Kernel Timers, Threads, and Workqueues 7. Section 2: Delving Deeper
8. Kernel Synchronization - Part 1 9. Kernel Synchronization - Part 2 10. Other Books You May Enjoy

Enabling and disabling IRQs

Typically, it's the core kernel (and/or arch-specific) code that handles low-level interrupt management. This includes doing things such as masking them as and when required. Nevertheless, some drivers, as well as the OS, require fine-grained control when enabling/disabling hardware interrupts. As your driver or module code runs with kernel privileges, the kernel provides (exported) helper routines that allow you to do exactly this:

Brief comment API or helper routine
Disable/enable all interrupts on the local processor
Unconditionally disables all interrupts on the local (current) processor core. local_irq_disable()
Unconditionally enables all interrupts on the local (current) processor core. local_irq_enable()
Saves the state (interrupt mask) of, and then disables all interrupts on  the local (current) processor core. The state is saved in the flags parameter that's passed. local_irq_save(unsigned long flags);
Restores the...
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