The HyperNews Linux KHG Discussion Pages

Note: Re: Network Device Drivers

Forum: Device Drivers
Keywords: network driver prototype functions
Date: Wed, 22 May 1996 16:23:09 GMT
From: Paul Gortmaker <>

> I don't know anything about this topic. The kernel source 
> includes a skeleton.c file that can get you started. 
> Someone has promised to write this section, so check back
> sometime... 

Hrrm, who was that? (just curious...)

Somebody asked me about a year or so ago as to what the basics
of a net driver would look like.  I haven't seen Alan's article
in linux journal, so this may be useless in comparison. 
Regardless, here it is anyway. 


1) Probe:
        called at boot to check for existence of card. Best if it
        can check un-obtrsively by reading from memory, etc. Can
        also read from i/o ports. Writing to i/o ports in a probe
        is *not* allowed as it may kill another device.
        Some device initialization is usually done here (allocating
        i/o space, IRQs,filling in the dev->??? fields etc.)

2) Interrupt handler:
        Called by the kernel when the card posts an interrupt.
        This has the job of determining why the card posted
        an interrupt, and acting accordingly. Usual interrupt
        conditions are data to be rec'd, transmit completed,
        error conditions being reported.

3) Transmit function
        Linked to dev->hard_start_xmit() and is called by the
        kernel when there is some data that the kernel wants
        to put out over the device. This puts the data onto
        the card and triggers the transmit.

4) Receive function
        Called by the interrupt handler when the card reports
        that there is data on the card. It pulls the data off
        the card, packages it into a sk_buff and lets the
        kernel know the data is there for it by doing a

5) Open function
        linked to dev->open and called by the networking layers
        when somebody does "ifconfig <device_name> up" -- this
        puts the device on line and enables it for Rx/Tx of

Someday, perhaps I will have the time to write a proper
document on the subject....   Naaaaahhhhhh.


1. More: Re: Network Device Drivers by Neal Tucker
1. More: network driver info by Neal Tucker
-> Idea: Network Driver Desprately Needed by Paul Atkinson
2. Question: Transmit function by Joerg Schorr
1. More: Re: Transmit function by Paul Gortmaker
-> Question: Skbuff by Joerg Schorr