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[英]Read/Write system call reads/writes data from/to which buffer

原文 2013-08-22 09:42:17 2 2 c/ linux/ serial-port

I am working with serial port programming and i have following doubt please clear it 我正在使用串行端口编程，并且我有以下疑问，请清除它

Does Read/Write system call reads and writes data directly from/to UART buffer? 读/写系统调用是否直接在UART缓冲区中读写数据？
Which buffer does Rx and Tx of " /proc/tty/driver/serial " refers to. / proc / tty / driver / serial的 Rx和Tx指的是哪个缓冲区。

Please clarify. 请澄清。

2 个解决方案

read() and write() access data via a so called file-descriptor return by a call to open() . read()和write()通过所谓的文件描述符（通过调用open()返回write()访问数据。

open() gets passed in the name of a serial device. open()以串行设备的名称传递。

Serial devices could be named "/dev/ttySX" with X={0..N} . 串行设备可以使用X={0..N}命名为"/dev/ttySX" 。

Why are you worried about: 您为什么担心：

Does Read/Write system call reads and writes data directly from/to UART buffer? 读/写系统调用是否直接在UART缓冲区中读写数据？

The kernel takes care of the actual read/write calls to a file regardless if its a device or a data file, in the case of device, IOCTL calls will be made to the device in question and handle it behind the scenes. 内核会处理对文件的实际读/写调用，而不管文件是设备还是数据文件，如果是设备，则将对有问题的设备进行IOCTL调用，并在后台进行处理。

Which buffer does Rx and Tx of "/proc/tty/driver/serial" refers to. “ / proc / tty / driver / serial”的Rx和Tx指的是哪个缓冲区。

Again, that is handled by the kernel and related IOCTL calls to the serial driver by way of device descriptor to the actual serial port. 同样，这是由内核和相关IOCTL调用（通过设备描述符到实际串行端口）对串行驱动程序进行处理的。

If still in doubt, a refresher on serial port programming under Un*x environments such as Linux/FreeBSD would be recommended. 如果仍然不确定，建议在诸如Linux / FreeBSD之类的Un * x环境下对串行端口编程进行复习。