Block devices and character Devices

I/O devices are generally divided into two categories: Block devices and character devices. Block devices store information in blocks of a fixed size. Each block has its own address. The size of a data block is usually between 512 bytes and 32768 bytes. The basic feature of Block devices is that each block can be read and written independently of other blocks. A disk is the most common block device. In most UNIX operating systems, Block devices only support block-based access, such as disks. kylin supports accessing Block devices in character mode, that is, it supports reading/writing disks and other Block devices in character units. Therefore, Block devices, such as disks, In the/dev directory appear as character devices. Therefore, the differences between character devices and Block devices are mainly reflected in the management method in the Kylin kernel, the operation method and the kernel/Device Driver Interface.