1. DEVICE DRIVER VINOD KAMATH CS691X PROJECT WORK

2. Introduction How to write/install device drivers Systems, Kernel Programming Character, Block and Network devices

3. Tasks involved Building and Running modules Character device drivers

4. Building device driver module Module vs. Applications –Appln - single task –Module - register for future Compiling and Loading –___KERNEL__, MODULE –insmod,rmmod –Global var-Symtab Do in Kernel space (not User space) –response time; block/network devs

5. Character device drivers Scull - Simple Char. Util. for Loading Localities –Acts on mem. Area as though it is a device –Demonstrate interface betn. Kernel and Char drivers –n devices for n mem. areas Major/Minor no.- (un)register chr_dev

6. Design and implementation of Scull File operations/structure –Device id. By file structure –Kenerl uses file ops. To access drivers functions Open and Close –Initialize device, usage count, Memory –Device-memory Link List Read and Write –Transfer data from Kernel-User Testing/Debugging –cp, cat, dd wls-l > dev/scull0

7. Examples-Hello World #define MODULE #include int init_module (void) {printk( Hello, World\n); return 0} void cleanup_module {printk( Goodbye, cruel World\n);}

8. Examples-Scull #define MODULE, __KERNEL__ #include …. Struct file_operations d0_fops = {r,w,o,c } int init_module (void) {malloc, reg do_fops} void cleanup_module (unreg, free...);l

9. Conclusions Writing device drivers is not for faint heart/Adventure Very careful with Kernel codes

10. Future work Try Advanced drivers, Scheduling Understand principle for multi user