GCC macro

Very good reference:

http://gcc.gnu.org/onlinedocs/gcc-3.1.1/cpp/Macros.html#Macros

#define __IRQ_SYSTMR(_X) IRQ_TMR ## _X
#define _IRQ_SYSTMR(_X) __IRQ_SYSTMR(_X)
#define IRQ_SYSTMR _IRQ_SYSTMR(CONFIG_IPIPE_SYS_TIMER)

#ifdef CONFIG_BF533
#define __IRQ_PRIOTMR(_X) CONFIG_TIMER ## _X
#else
#define __IRQ_PRIOTMR(_X) CONFIG_IRQ_TMR ## _X

create kernel patch

1. make clean
2. make mrproper
3. diff -urN -x Entries -x Entries.Log -x Repository -x Root -x .config
-x .version -x .config.* -x rootfs.img -x *.cmd -x *.o -x Tag -x linux
-x *.rej -x *.orig -x *.bak $1 $2