Differences between an io-net driver and an io-pkt driver

The good news is that io-net and io-pkt drivers are actually pretty similar. There are a few fundamental differences, which we'll discuss below.

One major difference between io-net and io-pkt is that in io-net, an npkt is used as the fundamental packet buffer, while in io-pkt, an mbuf is used instead. For information about some handy mbuf macros that are defined in <sys/mbuf.h>, see the NetBSD documenation at http://netbsd.gw.com/cgi-bin/man-cgi?mbuf++NetBSD-current.

Any network driver can be divided up into the following functional areas:

• Initialization
• Transmit
• Receive
• Link State Change Handling
• Control (e.g. devctl() and ioctl())
• Shutdown

It can be helpful to look at the source (see the Networking project on our Foundry 27 website, http://community.qnx.com) to io-net and io-pkt drivers for the same hardware, and contrast the differences. For example, for PCI, you could compare speedo or i82544, and for non-PCI, you could compare mpc85xx.