Date: Fri, 5 Feb 1999 11:22:47 -0500 (EST) From: Ilhwan Kwon <ik26+@andrew.cmu.edu> To: freebsd-hackers@freefall.cdrom.com Subject: [help] creating system calls Message-ID: <EqilfLe00Ui503yG00@andrew.cmu.edu>
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Hi.
I am trying to write my own system call functions for BSD.
I am trying to calculate the maximum amount of memory a PC needs
when it is used as a router.
First, I declare "u_long max_memused" in /usr/src/sys/sys/mbuf.h.
Second, I add following code in m_devget function in
/usr/src/sys/kern/uipc_mbuf.c.
u_long mem_used = size of memory currently used by mbufs and clusters.
if(mem_used > max_memused) max_memused = mem_used;
Third, I make prototype for my system calls in mbuf.h like following.
long get_mem_stat __P((void));
void clear_mem_stat __P((void));
Fourth, I declare above system calls in uipc_mbuf.c like following.
long get_mem_stat(){
return (long) max_memused;
}
void clear_mem_stat(){
max_memused = 0;
}
Fifth, I put entries in init_sysent.c like following.
struct sysent sysent[] = {
/*......*/
{0, (*sy_call)get_mem_stat}, /*241 = get_mem_stat */
{0, (*sy_call)clear_mem_stat}, /*242 = clear_mem_stat */
/* ..... */
};
the 241th and 242th wer originally looked like {0, (*sy_call)no_sys},
finally, I put entries in syscalls.c
"get_mem_stat" /*241 = get_mem_stat*/
"clear_mem_stat" /*242 = clear_mem_stat*/
they were originally "no_sys".
Now, I recompile the kernel and reboot. but kernel library is not updated.
I copy /usr/src/sys/sys/mbuf.h to /usr/include/sys/mbuf.h.
I write a small program which includes <sys/mbuf.h> and calls get_mem_stat
and clear_mem_stat system calls.
Whe I compile, I get
"get_mem_stat" : undefined reference from the text segent"
"clear_mem_stat" : undefined reference from the text segent"
What did I do wrong?
Any help on this matter will be greatly appreciated.
Thanks
-James Kwon
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