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有点不清楚LZ你想问啥。下面是E1000硬件手册里关于CHECKSUM部分
2.7.1 Checksum Offloading
The Ethernet controller provides the ability to offload the IP, TCP, and UDP checksum requirements
from the software device driver. For common frame types, the hardware automatically
calculates, inserts, and checks the appropriate checksum values normally handled by software.
For transmits, every Ethernet packet might have two checksums calculated and inserted by the
Ethernet controller. Typically, these would be the IP checksum, and either the TCP or UDP
checksum. The software device driver specifies which portions of the packet are included in the
checksum calculations, and where the calculated values are inserted via descriptors (refer to
Section 3.3.5 for details).
For receives, the hardware recognizes the packet type and performs the checksum calculations and
error checking automatically. Checksum and error information is provided to software through the
receive descriptors (refer to Section 3.2.9 for details).
ref:
http://download.intel.com/design ... s/8254x_GBe_SDM.pdf |
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