System calls and library calls

I have wondered for sometime what the difference is between system calls (found in section 2 of the man pages) and library calls (in section 3). Its simple...

system calls are provided by the system and are executed in the system kernel. They are entry points into the kernel and are therefore NOT linked into your program. These are not portable calls.
Library calls include the ANSI C standard library and are therefore portable. These functions are linked into your program.

It is worth noting that, because system calls are part of the O/S. The program has to make a context switch to the kernel when they are called and because of this, they have a high startup overhead. The upside is that the time executing these routines is assigned to the OS and not the user program.

Top

See also:

file: /Techref/language/ccpp/CREF/LIBRARIES/syscalls.htm, 1KB, , updated: 2003/3/20 10:39, local time: 2012/5/25 07:38,

^{38.107.179.234:LOG IN}

©2012 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?

Please DO link to this page! Digg it! / MAKE! /

<A HREF="http://www.piclist.com/techref/language/ccpp/CREF/LIBRARIES/syscalls.htm"> System calls and library calls</A>

Did you find what you needed?

"No. I'm looking for: "
"No. Take me to the search page."
"No. Take me to the top so I can drill down by catagory"
"No. I'm willing to pay for help, please refer me to a qualified consultant"
"No. But I'm interested. me at when this page is expanded."

Check out Peter Cousens EXCELLENT
Calculator 7-seg LED chars, port values, resistor color codes and common values, ohms law, wavelength / frequency, RMS and Peak, max value for x bits, etc...