System Calls
Content
System Calls
1. What is a system call? a. System call is a interface that gives applications access to HW and other OS resources. 2. What is the purpose of system call layer in linux? a. It provides abstracted hardware interface to user space. b. System calls ensure system security and stability. i. Kernel arbitrates access based on permissions and other criterion. c. A single common layer between user space and rest of the system allows for virtual system 3. What is a syscall number? a. In Linux, each system call is assigned a number called syscall number. 4. What does sys_call_table hold? a. Kernel keeps a list of all registered system calls in sys_call_table. 5. What is a system call context? a. System call context is process context. But kernel executes system call on behalf of process in kernel mode. 6. In what mode system call is run? a. Kernel mode 7. How to bind a system call? a. After system call is written, it needs to be registered as an official system call i. Add an entry to the end of sys_call_table ii. For each architecture supported, the syscall number needs to be defined in include/asm/unistd.h iii. The sys call needs to be compiled into kernel image.
1. What is a system call? a. System call is a interface that gives applications access to HW and other OS resources. 2. What is the purpose of system call layer in linux? a. It provides abstracted hardware interface to user space. b. System calls ensure system security and stability. i. Kernel arbitrates access based on permissions and other criterion. c. A single common layer between user space and rest of the system allows for virtual system 3. What is a syscall number? a. In Linux, each system call is assigned a number called syscall number. 4. What does sys_call_table hold? a. Kernel keeps a list of all registered system calls in sys_call_table. 5. What is a system call context? a. System call context is process context. But kernel executes system call on behalf of process in kernel mode. 6. In what mode system call is run? a. Kernel mode 7. How to bind a system call? a. After system call is written, it needs to be registered as an official system call i. Add an entry to the end of sys_call_table ii. For each architecture supported, the syscall number needs to be defined in include/asm/unistd.h iii. The sys call needs to be compiled into kernel image.
