<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML ><HEAD ><TITLE >_syscallN macro</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Implementing a System Call on Linux 2.6 for i386" HREF="index.html"><LINK REL="PREVIOUS" TITLE="testmycall.c (new user space source file to be created)" HREF="x156.html"><LINK REL="NEXT" TITLE="Testing our new system call" HREF="x204.html"></HEAD ><BODY CLASS="sect1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Implementing a System Call on Linux 2.6 for i386</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x156.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x204.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="sect1" ><H1 CLASS="sect1" ><A NAME="AEN173" ></A >16. _syscallN macro</H1 ><P ></P ><OL TYPE="1" ><LI ><P >_syscall0(int,mycall) indicates that:</P ></LI ><LI ><P >The name of the system call is mycall.</P ></LI ><LI ><P >It takes zero arguments.</P ></LI ><LI ><P >It returns an int.</P ></LI ></OL ><P ></P ><P ></P ><OL TYPE="1" ><LI ><P >_syscall1(int,mycall,int,number) indicates that:</P ></LI ><LI ><P >The name of the system call is mycall.</P ></LI ><LI ><P >It takes one argument.</P ></LI ><LI ><P >The argument is an int named number.</P ></LI ><LI ><P >It returns an int.</P ></LI ></OL ><P ></P ><P >When you expand _syscall1(long,mycall,int,i), you get the following code:</P ><P >long mycall(int i)</P ><P >{</P ><P >return syscall(__NR_mycall, i);</P ><P >}</P ><P ></P ><P >But the definition of _syscallN macros are different in the kernel. You can look at /usr/src/linux/include/asm-i386/unistd.h for the definition.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x156.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x204.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >testmycall.c (new user space source file to be created)</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" > </TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Testing our new system call</TD ></TR ></TABLE ></DIV ></BODY ></HTML >