1 / 14

Lab 3 System Call

Lab 3 System Call. Operating System Lab. What is a System Call? (1/3). System call provide the interface between a process and an operation system . The mechanism used by an application program to request service from the operating system. What is a System Call? (2/3).

karan
Download Presentation

Lab 3 System Call

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lab 3System Call Operating System Lab

  2. What is a System Call? (1/3) • System call provide the interface between a process and an operation system. • The mechanism used by an application program to request service from the operating system NCHU System & Network Lab

  3. What is a System Call? (2/3) • System calls can be grouped roughly into five major categories： • Process control • File management • Device management • Information maintenance • Communications NCHU System & Network Lab

  4. What is a System Call? (3/3) NCHU System & Network Lab

  5. How to Add a System Call (1/9) • STAGE 1:  Add system call and then make kernel • The implementation of system calls is within the kernel • Thus, if we add a new system call • Kernel is changed • Re-make and re-install the kernel • STAGE 2 : Add a user program and call system call • Test the correction of our new system call NCHU System & Network Lab

  6. How to add a system call(2/9) • STAGE 1:  Make Kernel and add system call • 1. Downlaod new Source Code from www.kernel.org to /usr/src. • 2. [root@localhost~ ]#tar -zxvf linux-2.6.22.6 tar.gz // Un-compress and un-archive NCHU System & Network Lab

  7. How to Add a System Call (3/9) • 3. • Edit file /usr/src/ linux-2.6.22.6 /arch/i386/kernel/syscall_table.S • Put a new system call into system_call_table[root@localhost~ ]#vim /usr/src/ linux-2.6.22.6 /arch/i386/kernel/syscall_table.S  • We will see the code like this in this file:.dataENTRY(sys_call_table)      .long     sys_ni_call                            /* 0 */ …… • At the bottom of sys_call_table, create a new system call name • For example: • .long sys_myservice/*  324  */ NCHU System & Network Lab

  8. How to Add a System Call(4/9) • 4. • Write the code of the new system call [root@localhost~ ]# vim /usr/src/linux-2.6.22.6/arch/i386/kernel/myservice.c • We want to print “*******This is my new system call********” #include <linux/linkage.h>#include <linux/kernel.h> asmlinkage int sys_myservice(void){printk(“********This is my new system call********\n”);return 0;} NCHU System & Network Lab

  9. How to Add a System Call (5/9) • 5. • Edit file /usr/src/ linux-2.6.22.6 /arch/i386/kernel/Makefile • We need to re-make our kernel so that the new system call can be in effect • Add our new system call file into the kernel’s makefile. • Also compiler the code of new system call when compiling the kernel • [root@localhost~ ]# vim /usr/src/linux-2.6.22.6/arch/i386/kernel/Makefile obj-y += myservice.o NCHU System & Network Lab

  10. How to Add a System Call (6/9) • 6. • build system call 「stub」to allow user program call this system call • [root@localhost~ ]#vim /usr/src/linux-2.6.22.6/include/asm-i386/unistd.h • The content of this file likes this： …  #define __NR_io_destroy         246 #define __NR_io_getevents       247 #define __NR_io_submit          248 #define __NR_io_cancel          249…. • Add #define __NR_(name) #define __NR_myservice          324 • The number of total system call is added one#define __NR_syscalls 325 NCHU System & Network Lab

  11. How to Add a System Call (7/9) • 7. • Make new kernel contaning the new system call • make mrproper • remove all generated files + config + various backup files • make menuconfig • Use text mode to select what drivers or modules that we want to use. • make modules • Compile modules • make modules_install • Install modules in /lib/modules/linux-2.6.22 • make • Compile kernel • make install • Install kernel • [root@localhost~ ]# make modules && make modules_install && make && make install NCHU System & Network Lab

  12. How to Add a System Call (8/9) • STAGE 2 : Write a new user program to test the system call • 1. • Write a new user program  [root@localhost~ ]#vim testsyscall.c #include <linux/unistd.h>#define __NR_myservice        324 _syscall0(int、myservice); int main (){myservice();return 0;} NCHU System & Network Lab

  13. How to Add a System Call (9/9) • 2. • Compile this file • [root@localhost~ ]#gcc -Wall testsyscall.c -o testsyscall.o • 3. • It’s show time • [root@localhost~ ]#./testsyscall.o NCHU System & Network Lab

  14. Reference • Operation system concepts sixth edition • Wikipedia • http://en.wikipedia.org/wiki/System_call • 鳥哥的 Linux 私房菜 • http://linux.vbird.org/ • Google • Search key word “system call” NCHU System & Network Lab

More Related