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This article will explain in detail how to deal with terminal sharing in the Linux system. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

In the Linux system, multiple devices can share an interrupt number, and interrupt handlers that share the same interrupt form a linked list, and even programs that do not produce interrupts will be executed.

Shared handlers are similar to non-shared handlers in registration and operation, but there are three main differences:

* the parameter flags of request_irq () must set the SA_SHIRQ flag.

* the dev_id parameter must be unique for each registered interrupt handler. A pointer to any device structure meets this requirement; the device structure is usually chosen because it is unique and may be used by interrupt handlers. You cannot pass a null value to a shared handler.

* the interrupt handler must be able to tell whether its device is actually causing an interrupt. This requires not only the support of the hardware, but also the relevant processing logic in the processor. If the hardware does not support this function, the interrupt handler will be at a loss as to whether it is the corresponding device or other devices that share the interrupt line.

All drivers that share the breaklines must meet the above requirements. As long as any device is not shared according to the rules, the break line cannot be shared. When you specify the SA_SHIRQ flag to call request_irq (), you can succeed only if the break line is not currently registered, or if all registered handlers on that line specify SA_SHIRQ. Note that 2.6 is different from previous kernels in that shared handlers can be mixed with SA_ INTERRUPT. After the kernel receives an interrupt, it invokes each handler registered on the interrupt line in turn. Therefore, a handler must know whether it is responsible for the interrupt. If the device associated with it does not cause an interrupt, the handler should exit immediately. This requires the hardware device to provide a status register (or similar mechanism) so that the interrupt handler can check. There is no doubt that most hardware provides this functionality.

This is the end of the article on "how to deal with terminal sharing in the Linux system". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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