Where is the Ring Buffer in linux kernel networking?

Question

I know when you recv data from NIC, there is a ring buffer that NIC DMA data into it, and some NIC supports multiple ring buffer. But I wonder where does the ring buffer store, in which struct, or should I manually alloc a ring buffer when writing a Network Driver?

where does the ring buffer store, and what does it look like, better if show me the source code, thank you a lot.

Answer 1

image it:

your question ---- where does the ring buffer store, in which struct, or should I manually alloc a ring buffer when writing a Network Driver?

• it's created by net driver, the ring buffer, using kernel's fifo data structor, and its memory is allocated through kernel's method, thus located in kernel's data segment.

• the kernel(without net driver) called net driver to pull up the nic(hardware), and the net driver manage the ring buffer for the kernel's ip protocal stack to use.

• when data come from nic, nic do 2 things(which is not drawn in the picture above):

  1. save data through DMA into the ring buffer
  2. hardware interrupt: tell cpu(the kernel thread) to recv data from the ring buffer