ifdef _KERNEL__
1)does the __ of the __KERNEL__ means anything to the compiler?
#define namei(pathname) __namei(pathname, LOOKUP_FOLLOW)
2) WHAT'S THIS __namei?
#define FIBMP __IO(0x00, 1)
3) what's this __IO?
#define pr_info(fmt, arg..) |
printfk(KERN_INFO fmt, ##arg)
4)what's this ##?