Hi all: asmlinkage is only defined in arch ia64 and x86_32: 1. arch/x86/include/asm/linkage.h: #ifdef CONFIG_X86_32 #define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0))) #endif /* CONFIG_X86_32 */ 2. arch/ia64/include/asm/linkage.h: #define asmlinkage CPP_ASMLINKAGE __attribute__((syscall_linkage)) 3. arch independent include/linux/linkage.h: #ifdef __cplusplus #define CPP_ASMLINKAGE extern "C" #else #define CPP_ASMLINKAGE #endif #ifndef asmlinkage #define asmlinkage CPP_ASMLINKAGE #endif As kernelnewbies FAQ(https://kernelnewbies.org/FAQ/asmlinkage) said, in short, asmlinkage tells your compiler to look on the CPU stack for the function parameters, instead of registers. So, there are two questions: 1. asmlinkage is only defined in x86_32 and ia64, what about other archs? How do they achieve the same effect as mentioned above? 2. "asmlinkage __visible void dump_stack(void)", dump_stack does not have any parameter, so why do it need asmlinkage? Thanks! Lv Ying