va_alist ( using variable list in 64 bit machine )

va_alist ( using variable list in 64 bit machine )

I am trying to implement a print function in the kernel module for my
learning purposes. I am emulating it on QEMU.
#define va_alist __builtin_va_alist
#define va_dcl __builtin_va_list_t
__builtin_va_list; ...
#define va_start(ap) __builtin_varargs_start(ap)
#define va_arg(ap, type) __builtin_va_arg((ap), type)
#define va_end(ap) __builtin_va_end(ap)
But I am getting the error that __builtin_va_alist is undeclared. Should I
try to find the definition of __builtin_va_alist also and put it in my
include file or am I not aware of something here? Also, If i change
__builtin_va_alist to __builtin_va_list ( note: a is not there ), then I
am getting an error called implicit declaration of __builtin_varargs_start
. Kindly help.
Thanks
Chidambaram