Question

so far i have only used file operational structure in device driver.
Using system call open & read , write.

How to open device driver & transmit data using net_device_ops ?
Is there reference example on net for the user program to interact with it ?

http://lnxpps.de/rpie/mcp2515_mod.c

Answer 1

I’m not sure I understand the question, so let me know if my answer doesn’t make sense.

I see you have defined functions for .ndo_open, .ndo_stop, and .ndo_start_xmit. .ndo_open is called by the kernel when you configure the interface using ifconfig up or use ifconfig to assign an address to the interface. .ndo_stop is called by the kernel when you remove the module or if you shutdown the interface using ifconfig down.

ifconfig is described here: http://linux.die.net/man/8/ifconfig

.ndo_start_xmit is called by the kernel network stack when a socket is used to transmit a packet. So, to transmit data using .ndo_start_xmit you’ll need to create a socket, assign an appropriate destination address, and send the data via the socket. If you’re using IP, there are tools you can use send packets easily, such as netperf or iperf.