Writing a System Call

[ThePestilent]

Hi everyone

I need to write a system call for the first time and it's proven to be pretty frustrating - I'm having trouble wrapping my head around it. But I figure I'll start off slow. Here is my declaration in sys.c:

SYSCALL_DEFINE1 (getprinfo, struct prinfo *info)

The compiler returns:

/home/dtroberts/kernelSrc/kernel/sys.c:1816:1: error: macro "__SC_DECL1" requires 2 arguments, but only 1 given

There are two arguments there. I can also see that info isn't being included in the compiler's output; it's saying that info is undeclared. Am I using SYSCALL_DEFINE1 incorrectly? Am I treating it too much like a user-space program?

Thank you.

[Cabhan]

Doing a quick trace through the /include/linux/syscalls.h file in the kernel source code implies to me that your arguments and their types should be separate:

SYSCALL_DEFINE1(getprinfo, struct prinfo *, info)

Having never written a system call, I'm not entirely sure that this is accurate, but given that __SC_DECL1 is defined as:

#define __SC_DECL1(t1, a1)	t1 a1

I suspect that this is true.

[ThePestilent]

Doing a quick trace through the /include/linux/syscalls.h file in the kernel source code implies to me that your arguments and their types should be separate:

SYSCALL_DEFINE1(getprinfo, struct prinfo *, info)

Having never written a system call, I'm not entirely sure that this is accurate, but given that __SC_DECL1 is defined as:

#define __SC_DECL1(t1, a1)	t1 a1

I suspect that this is true.

Yep, you were right. Defining it as you said fixed my error. Thank you!