realtime programming

gaihua · 10-01-2006, 12:05 AM

I did install Fedora 5 distribution my my computer. I did try to do some realtime programing now. However, I can't pass the compiler because the glibc doesn't support all realtime commands. I can't pass it because gcc don't know the shm_open() and sem_wait(), etc. Anybody know how to make them work??

Denes · 10-02-2006, 11:35 AM

Are you talking about using shared memory and a cross process semaphore in Linux? If so check out the book Advanced Linux Programming (you can find it for free on the web), Chapter 5 - Interprocess communication. Section 5.1 discusses using shared memory, section 5.2 discusses interprocess semaphores.

I hope you know that FC5 is not a real time distribution and does not have real time extensions built in, but depending on your real time requirements it may work for you.

gaihua · 10-05-2006, 07:40 AM

Thank you, Denes. I can use gcc -lrt programm.c to pass the complier. Could we install some library or complier under the FC5 to make it work for realtime programming?

Denes · 10-05-2006, 10:53 AM

There is a library out there called RTAI which has promise but I have never personally used it, although I know someone who has and they had a rough time with certain hardware incompabilities. I believe there are others.

There is a Linux distribution devoted specifically to real time called RedHawk, but it is not free.

There is also another one called LynxOS (also not free) that has a POSIX layer for application compatibility. I have used this OS and it works but only supports limited hardware since it's device drivers are not Linux compatible.

Anyway, as I said before, Linux will generally give you good, but not guaranteed performance. And again it all depends on your real time requirements.

gearheadgeek · 08-09-2007, 10:29 AM

Quote:

Originally Posted by Denes

If so check out the book Advanced Linux Programming (you can find it for free on the web), Chapter 5 - Interprocess communication. Section 5.1 discusses using shared memory,

This only talks about Sys V shared memory - how about a pointer for Posix shared memory?

asprakash · 08-11-2007, 02:59 AM

RTLinux and RTAI provides you the real time linux capabilities. But you need to compile a separate kernel and patch the rtlinux.
frankly tel you its a little bit tough job for beginners, initially.
Did you tried, -lrt option?
You should have to install glibc-2.2 or later version for supporting this real time libraries.