Ethernet Controller I211 —Introduction
16
1.7.2 Receive Data Flow
Table 1-12 lists a high level description of all data/control transformation steps needed for receiving
Ethernet packets.
Table 1-12. Receive Data Flow
Step Description
1
The host creates a descriptor ring and configures one of the I211's receive queues with the address location,
length, head, and tail pointers of the ring (one of available Rx queues).
2
The host initializes descriptors that point to empty data buffers. The host places these descriptors in the correct
location at the appropriate Rx ring.
3 The host updates the appropriate queue tail pointer (RDT).
4
The I211's DMA senses a change of a specific RDT and as a result sends a PCIe request to fetch the descriptors
from host memory.
5
The descriptors content is received in a PCIe read completion and is written to the appropriate location in the
descriptor queue internal cache.
6 A packet enters the Rx MAC. The Rx MAC checks the CRC of the packet.
7 The MAC forwards the packet to an Rx filter.
8
If the packet matches the pre-programmed criteria of the Rx filtering, it is forwarded to the Rx FIFO. VLAN and
CRC are optionally stripped from the packet and L3/L4 checksum are checked and the destination queue is fixed.
9
The receive DMA fetches the next descriptor from the internal cache of the appropriate queue to be used for the
next received packet.
10
After the entire packet is placed into the Rx FIFO, the receive DMA posts the packet data to the location indicated
by the descriptor through the PCIe interface. If the packet size is greater than the buffer size, more descriptors are
fetched and their buffers are used for the received packet.
11
When the packet is placed into host memory, the receive DMA updates all the descriptor(s) that were used by
packet data.
12
After enough descriptors are gathered for write back or the interrupt moderation timer expires or the packet
requires immediate forwarding, the receive DMA writes back the descriptor content along with status bits that
indicate the packet information including what off loads were done on that packet.
13
After the interrupt moderation timer completes or an immediate packet is received, the I211 initiates an interrupt
to the host to indicate that a new received packet is already in host memory.
14
Host reads the packet data and sends it to the TCP/IP stack for further processing. The host releases the
associated buffers and descriptors once they are no longer in use.
剩余531页未读，继续阅读
tylgzhy
- 粉丝: 0
- 资源: 4
我的内容管理
收起
- 我的资源
快来上传第一个资源
我的收益 登录查看自己的收益
我的积分
登录查看自己的积分
我的C币
登录后查看C币余额
我的收藏 
我的下载 
下载帮助
会员权益专享
最新资源
- zigbee-cluster-library-specification
- JSBSim Reference Manual
- c++校园超市商品信息管理系统课程设计说明书(含源代码) (2).pdf
- 建筑供配电系统相关课件.pptx
- 企业管理规章制度及管理模式.doc
- vb打开摄像头.doc
- 云计算-可信计算中认证协议改进方案.pdf
- [详细完整版]单片机编程4.ppt
- c语言常用算法.pdf
- c++经典程序代码大全.pdf
- 单片机数字时钟资料.doc
- 11项目管理前沿1.0.pptx
- 基于ssm的“魅力”繁峙宣传网站的设计与实现论文.doc
- 智慧交通综合解决方案.pptx
- 建筑防潮设计-PowerPointPresentati.pptx
- SPC统计过程控制程序.pptx
资源上传下载、课程学习等过程中有任何疑问或建议，欢迎提出宝贵意见哦~我们会及时处理！
点击此处反馈
