How / from where to start on Solaris Driver developement?

Question

Hi,
'm a User domain developer, want to also learn about driver developement.
Please give me pointers so that I can start with
Thanks,
-Vikrant

Answer 1

First of all you should download the following two documents:
- Writing Device Drivers
- STREAMS Programming Guide
If you want to develop USB drivers you must have USBA 1.0 installed (Solaris 8/9 has 0.8 as default) and additionally download the "USB DDK" from Sun.
A device driver is an object file (created by "ld -r ..."). You cannot decide if you use 32 or 64 bit. On a 64 bit OS you MUST use 64 bit code.
If you use GCC: On Sparc machines 64 bit code is generated using "-m64", not using "-xarch=v9".
The driver must provide three functions: "_init", "_info" and "_fini" (see first document).
There are two types of drivers:
1) Streams drivers (described in the second document) are drivers for stream devices. These are all devices that implement a character stream and can be used with "streamio" ioctls. Examples are: All terminals and serial ports, printer ports, mice, keyboards, ...
These devices communicate with the system calls (e.g. read, write, ioctl) using special data packets. Therefore programming Streams drivers is very different from writing other drivers.
All streams devices are character devices.
You can also write streams modules (see man streamio, I_PUSH). Such modules are "filters" that can modify the data between the device driver and the application.
2) Other drivers. They may be character or block devices. These drivers have different functions for different function calls. Example: The "ioctl" function call will call the function "MyDriver_Ioctl" of your driver.
I think writing a non-streams driver is way more simple than writing a streams driver. I had some system crashes when running instable self-written streams drivers. However some drivers must be streams drivers e.g. if you want to use the device as a terminal device or if you want to push modules using I_PUSH.
Unlike Linux the OS detects the presence of hardware and decides when to load a driver. You create the file /kernel/drv/NameOfYourDriver.conf with driver settings. This file also contains the information that your driver does not require hardware (e.g. ram disks). You must add your driver to the system by typing "add_drv NameOfYourDriver". Use the "-i" option to tell the system which hardware is handled by your driver.
Martin