On 10/25/05, Raju RajaRam <oyeraju@xxxxxxxxx> wrote: > Hi, > iam new to linux kernel. > Can anyone tell me how to get the sequence of function called during the > library/system call invocation. > > For example frmo user application if we invoke read() function call which > functions are called in function. Any library function our application calls, further calls the system call intreface thru int x080 instruction, this instruction changes the CPU mode from user mode to kernel mode, switches the stack from process specific user stack to process specific kernel stack and then just after int x080 instruction CPU is pointed to execute system_call () assembly function (find it in entry.S kernel source file). This kernel function retrieves the system call arguments from CPU register and pushes all the processor registers on process specific kernel stack. It performs some checks related to ptrace (if our process is being monitered by any debugger), finally it calls the actuall system call function (starts with "sys_" in kernel sources) by looking in system call table at system call number index (system call number is passed library function as an argument to system call). This called function is actually responsible for delivering the service requested by library function. Hope this clears something about how system calls are done on Linux. cheers !! -Guarav i know one method thru strace, is there > any other way to know that. > > thanks. -- - Gaurav my blog: http://lkdp.blogspot.com/ -- -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
