CODEWITHSUNDEEP
linuxlinux-kernellinux-device-driver
Zeeshan Haris
Zeeshan Haris

Reputation: 21

How does the Linux Operating System understand the underlying hardware?

I want to learn how Linux OS understands the underlying hardware.Can anyone suggest me where to start for getting this understanding,As of now i just know the '/dev' sub-directory plays a vital role in that.

It has the device special files which are like a portal to the device driver which then takes it to the physical device.

I read somewhere that Udev daemon listens to the netlink socket to collect this information and Udev device manager detects addition and removal of devices as they occur.

But with these i am just not satisfied with the thought of how Linux reads the hardware.

Please let me know where to start to understand this, i am so thankful to anyone trying to help.

Upvotes: 0

Views: 475

Answers (1)

user2699113
user2699113

Reputation: 4509

I think at first you need to find out how the memory mapping works. What is the address space and how it relates to physical memory. Then you could read about how the hardware is mapped in address space and how to access it. It is a big amount of docs to read. Some of those information are in Linux Documentation Project.

Additionally some knowledge about electronic would be helpful.

In general - Linux for communication with devices needs some "channel" of communication. This channel may be for example ISA, PCI, USB, etc bus. For example PCI devices are memory mapped devices and Linux kernel communicates with them via memory accesses. So first Linux needs to see given device in some memory area and then it is able to configure this device and do some communication with it.

In case of USB devices it is a little bit complicated because USB devices are not memory mapped. You need to configure USB host first to be able to communicate with USB devices. Every communication with USB device is achieved via USB host.

There are also devices which are not connected via ISA, PCI or USB. They are connected directly to the processor and visible under some memory address. This solution is usually implemented in embedded devices. For example ARM processors use this approach.

Regarding udev - it is user-space application which listens for events from Linux kernel and helps other applications with recognizing device addition and configuration.

Upvotes: 4

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