source: liacs/os/assignment6/README@ 422

# OS Assignment 6

# Rick van der Zwet - 0433373

# $Id: README.txt 619 2008-05-19 19:35:46Z rick $



# Please let me know if you are also interested in the actual diff of

# the files if those brief outputs are not sufficient



# WARNING: Using different system, Ubuntu Linux under Parallels, kernel

# version 2.6.24.3 on a x86 system

$ cd /usr/src/linux/kernel

$ vim sys.c



# Syscall lives in different location

$ vim arch/x86/kernel/syscall_table_32.S

code: .long sys_multiply              /* 325 *



# __NR_syscall_max has been replaced by NR_syscalls in file

$ vim include/asm/unistd_32.h



# include/linux/syscalls.h does not need to be altered anymore, as it

# directly links to include/asm/unistd_32.h



# Build new kernel



#Code used:

=== BEGIN CODE ===

#include <stdio.h>

#include <sysexits.h>

#include <unistd.h>

int main() {

    printf("6 * 7 = %li\n", syscall(325, 6, 7));

    return(EX_OK);

}

=== END CODE ===

$ gcc -Wall -o syscall-test syscall-test.c

$ ./syscall-test

# When calling it on original kernel the output is `6 * 7 = -1', the

# `-1' is in fact syscall error return code, due the fact the syscall

# does not exists yet



# Install new kernel and reboot

$ ./syscall-test

# After rebooting the output is set to be `6 * 7 = 42`

$ time ./syscall-test

# when using larger numbers and `time' to measure output it will become

# clear the program is spending almost all of his time in sys(tem) mode.