Pentium 4 posiada instrukcję sysenter ().
Śledzenie wywołań Wywołania systemowe można śledzić za pomocą programu truss (większość uniksów) lub strace (Linux).
Oto przykład działania strace dla trywialnego programu true:
execve("/bin/true", ["true"], [/* 35 vars */]) = 0 uname({sys="Linux", node="myhost", ...}) = 0 brk(0) = 0x804a308 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.preload", O_RDONLY) = -1 ENOENT (No such file or directory) open("/home/taw/local/lib/libc.so.6", O_RDONLY) = -1 ENOENT (No such file or directory) stat64("/home/taw/local/lib", {st_mode=S_IFDIR|0755, st_size=72, ...}) = 0 open("/etc/ld.so.cache", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=85050, ...}) = 0 old_mmap(NULL, 85050, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40012000 close(3) = 0 open("/lib/libc.so.6", O_RDONLY) = 3 read(3, "\\177ELF\\1\\1\\1\\0\\0\\0\\0\\0\\0\\0\\0\\0\\3\\0\\3\\0\\1\\0\\0\\0@Z\\1\\000"..., 1024) = 1024 fstat64(3, {st_mode=S_IFREG|0755, st_size=1109900, ...}) = 0 old_mmap(NULL, 1122692, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40027000 mprotect(0x40130000, 37252, PROT_NONE) = 0 old_mmap(0x40130000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x109000) = 0x40130000 old_mmap(0x40135000, 16772, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) =