How to call timer interrupt service routine on fedora core 4?

[liuyijun]

Hi,
I'm using fedora core 4. I'm doing my school project that requires me to write program in C and run on linux. I need to call timer interrupt service routine in the program, found a code that seems to be able to do it in windows, but when i compiled it in fedora, gcc doesn't recognise <dos.h> and <bios.h> that's included in the code.
Anyone knows how to call timer interrupt that gcc recognizes? Urgently need help! Thanks.

[markkuk]

All interrupt handling in Linux is done by the kernel. You can't "call timer interrupt" in an user-level program, you must use the POSIX timer functions like timer_create(), timer_gettime() and timer_delete().
See "man timer_create" and the Single Unix Specification

[liuyijun]

Thank you. I did some read-up on that. Tried out some example codes, unfortunately POSIX functions like clock_gettime etc don't seem to be supported in my time.h, looks like it requires POSIX.4? I tried out another function setitmer() and this one works ok. I suppose they are under different category of POSIX? Where or how can i download the POSIX.4 include files?

[markkuk]

The Fedora Core 4 time.h header declares clock_gettime(), timer_create() and all other POSIX timer functions. You don't need to download anything.
What's the exact error message you get when you try to use those functions?
Are you linking your code with librt? (-lrt)

[liuyijun]

I checked the time.h, some of the functions, eg clock_gettime() and timer_create() are declared as extern. When compiled, the error message is "undefined reference in clock_gettime".

Prior to this, i was trying to install rtai onto fedora 4 and ran some patches on the kernel following the instructions in http://www.cs.rose-hulman.edu/~ellis...9-adeos-howto/, with linux-2.6.11.tar.gz and adeos-linux-2.6.11-i386-r13.patch, i was able to proceed till the make all
step just before step 3 build RTAI stuff. During the make all step, i encountered a few errors after a long wait:
In file included from drivers/i2c/algos/i2c-algo-bit.c:31:
include/linux/i2c.h:58: error: array type has incomplete element type
include/linux/i2c.h:197: error: array type has incomplete element type
make[3]: *** [drivers/i2c/algos/i2c-algo-bit.o] Error 1
make[2]: *** [drivers/i2c/algos] Error 2
make[1]: *** [drivers/i2c] Error 2
make: *** [drivers] Error 2

and thus couldn't proceed anymore. would these patches overwrite the original libraries?

[markkuk]

Originally Posted by liuyijun

I checked the time.h, some of the functions, eg clock_gettime() and timer_create() are declared as extern. When compiled, the error message is "undefined reference in clock_gettime".

This means you aren't linking with the necessary library. Add -lrt to the gcc command line.

[liuyijun]

ah... it works now. Thank you very much for your advice. You've provided a great help!