My problem is "select" system call always return -1 and errno is -4142, but sys_select has never been called. Think, it has some problem on handling system call. Because if I change SYS(sys_select, 5) to 4 arguments, sys_select will be executed. Thanks! Compiler: gcc-3.3.3 Kernel: mips-linux-2.4.25/mips-linux-2.4.26 Compile parameter: -Wno-inline \ -Werror-implicit-function-declarations \ -fno-PIC \ -fno-common \ -mno-abicalls \ -mlong-calls \ -march=r4600 \ -mtune=r4600 \ -G 0 \ -Wa,--trap