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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
</span><span lang="JA" style="font-size:10.0pt">王瘢雹哲</span><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> [mailto:wangzhe5004@gmail.com]
<br>
<b>Sent:</b> Monday, June 18, 2012 9:32 PM<br>
<b>To:</b> Jeff Haran<br>
<b>Cc:</b> kernelnewbies<br>
<b>Subject:</b> Re: A confusion about invoking my syscall<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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<p class="MsoNormal">2012/6/19 Jeff Haran <<a href="mailto:jharan@bytemobile.com" target="_blank">jharan@bytemobile.com</a>><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:kernelnewbies-bounces@kernelnewbies.org" target="_blank">kernelnewbies-bounces@kernelnewbies.org</a> [mailto:<a href="mailto:kernelnewbies-bounces@kernelnewbies.org" target="_blank">kernelnewbies-bounces@kernelnewbies.org</a>]
<b>On Behalf Of </b>??<br>
<b>Sent:</b> Monday, June 18, 2012 6:40 PM<br>
<b>To:</b> kernelnewbies<br>
<b>Subject:</b> A confusion about invoking my syscall</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hello everyone:<br>
<br>
I append a simple syscall in kernel. and the function is as follows:<br>
<br>
asmlinkage long sys_mysyscall(long data)<br>
{<br>
printk("This is my syscall!\n");<br>
return data;<br>
}<br>
<br>
and i test it sucessfully in user space . and the test program:<br>
<br>
#include <linux/unistd.h>
<br>
#include <syscall.h><br>
#include <sys/types.h><br>
#include <stdio.h><br>
<br>
<br>
<br>
int main(void)<br>
{<br>
long n = 0,m = 0,pid1,pid2;<br>
n = syscall(345,190);// #define __NR_mysyscall 345<br>
printf("n = %ld\n",n);<br>
pid1 = syscall(SYS_getpid); //getpid<br>
printf("pid = %ld\n",pid1);<br>
pid2 = syscall(20); //getpid<br>
printf("pid = %ld\n",pid2);<br>
return 0;<br>
}<br>
and the result:<br>
n = 190<br>
pid = 4097<br>
pid = 4097<br>
<br>
but if the test program is:<br>
#include <linux/unistd.h><br>
#include <syscall.h><br>
#include <sys/types.h><br>
#include <stdio.h><br>
<br>
<br>
<br>
int main(void)<br>
{<br>
long n = 0,m = 0,pid1,pid2;<br>
n = syscall(345,190);// #define __NR_mysyscall 345<br>
printf("n = %ld\n",n);<br>
m = syscall(SYS_mysyscall,190);<br>
printf("m = %ld\n",m);<br>
pid1 = syscall(SYS_getpid); //getpid<br>
printf("pid = %ld\n",pid1);<br>
pid2 = syscall(20); //getpid<br>
printf("pid = %ld\n",pid2);<br>
return 0;<br>
}<br>
and the result:<br>
wanny@wanny-C-Notebook-XXXX:~/syscall/src$ gcc test1.c <br>
test1.c: In function ‘main’:<br>
test1.c:13:14: error: ‘SYS_mysyscall’ undeclared (first use in this function)<br>
test1.c:13:14: note: each undeclared identifier is reported only once for each function it appears in<br>
<br>
<br>
why i can't invoke my syscall with "SYS_mysyscall"?<br>
<br>
Thanks in advance!<o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#1F497D">Because it appears you never defined the symbol SYS_mysyscall.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#1F497D"> I think so,but where shoud i defne the symbol SYS_mysyscall ?</span><span style="color:#888888"> <o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#1F497D"> and where is the symbol </span><span style="color:#888888">SYS_getpid defined? <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="color:#1F497D">On my system /usr/include/bits/syscall.h, which is</span><span style="color:#1F497D"> </span><span style="color:#1F497D">being included in your program
because it includes syscall.h.<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Jeff Haran<o:p></o:p></span></p>
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