1 Noteworthy changes in release 4.10 (????-??-??)
2 ==============================================
5 * Added -yy option to print protocol and address information associated with
7 * Extended "-e read=set" and "-e write=set" options to cover sendmsg,
8 recvmsg, sendmmsg, and recvmmsg syscalls.
9 * Implemented full 32-bit decoding of ioctl commands
10 (addresses Fedora bug #902788).
11 * Implemented PTRACE_GETREGS API support on MIPS.
12 * Implemented decoding of getrandom and seccomp syscalls.
13 * Implemented full decoding of 64-bit capability sets.
14 * Implemented decoding of all prctl commands.
15 * Implemented decoding of parametrized ioctl commands.
16 * Implemented decoding of evdev ioctl commands.
17 * Implemented decoding of v4l ioctl commands.
18 * Implemented decoding of SG_IO v4 ioctl commands.
19 * Implemented decoding of FIFREEZE/FITHAW/FITRIM ioctl commands.
20 * Implemented decoding of FALLOC_FL_* fallocate flags.
21 * Enhanced socket decoder to support bluetooth sockets.
22 * Enhanced decoding of unlisted ioctl commands.
23 * Enhanced decoding of getsockopt and setsockopt syscall.
24 * Enhanced decoding of sysinfo syscall.
25 * Enhanced decoding of struct cmsghdr.
26 * Enhanced decoding of wait status.
27 * Enhanced aio support on non-x86 architectures by using external libaio.h.
28 * Added O_TMPFILE to the list of recognized open mode flags.
29 * Updated the list of filesystem type constants that is used in decoding
30 statfs family syscalls.
31 * Updated lists of CAP_*, PR_*, PTRACE_*, SCHED_*, SO_*, SOL_*, SWAP_FLAG_*,
33 * Updated lists of signal constants from Linux 3.19.
34 * Updated lists of errno constants from Linux 3.19.
35 * Updated lists of ioctl commands from Linux 3.9.
36 * Added new syscall entries to match Linux 3.19.
39 * Fixed various errors in mapping between syscall numbers and associated
40 information like the number of syscall arguments, the name of syscall,
42 * Fixed quoting issues in printing descriptors, filenames, network interface
43 names, struct utsname members, device/volume names of BLK* ioctl commands.
44 * Fixed uid_t/git_t decoding.
45 * Fixed potential out-of-bounds read issues in getdents/getdents64 decoders.
46 * Fixed potential open flags truncation on some architectures.
47 * Fixed decoding of struct ifreq.ifr_name.
48 * Fixed decoding of SIOCSIFNAME ioctl command.
49 * Fixed decoding of RENAME_* renameat2 flags.
50 * Fixed decoding of UTIME_NOW/UTIME_OMIT timeval structures.
51 * Fixed decoding of indirect ipc subcalls on some architectures.
52 * Fixed decoding of fanotify_mark syscall on 32-bit architectures.
53 * Fixed decoding of 32-bit stat structures on 64-bit architectures.
54 * Fixed decoding of 32-bit struct cmsghdr on 64-bit architectures.
55 * Fixed decoding of 32-bit preadv/pwritev offset on 64-bit architectures.
56 * Fixed instruction pointer output (-i option) on architectures that support
57 several personalities.
58 * Fixed behaviour of "-e read=set" and "-e write=set" when read and write
60 * Fixed build on systems where struct sigaction has no sa_restorer member.
61 * Fixed build with uclibc and musl libc.
64 * Linux kernel >= 2.5.46 is required.
65 Older versions without a decent PTRACE_SETOPTIONS support will not work.
67 Noteworthy changes in release 4.9 (2014-08-15)
68 ==============================================
71 * Disabled OABI support on ARM EABI systems by default,
72 added --enable-arm-oabi option to enable it at configure time.
75 * Added experimental -k option to print stack trace after each traced syscall.
76 * Added -w option to produce stats on syscall latency.
77 (addresses Debian bug #457497).
78 * Added ARC architecture support.
79 * Added PTRACE_GETREGS API support on PowerPC.
80 * Enhanced Bionic libc and musl libc support.
81 * Enhanced tracing of x86 personality processes on x86_64 and x32.
82 * Enhanced tracing of ARM personality processes on AArch64.
83 * Enhanced 32/64bit personality detection on PowerPC.
84 * Implemented decoding of add_key, ioprio_get, ioprio_set, kexec_load, keyctl,
85 renameat2, and request_key syscalls.
86 * Robustified decoding of select, pselect, and io_submit syscalls.
87 * Enhanced decoding of delete_module, fanotify_init, fanotify_mark, fcntl,
88 setdomainname, sethostname, setns, and sync_file_range syscalls.
89 * Enhanced decoding of signal bitmasks.
90 * Enhanced decoding of file descriptors.
91 * Enhanced siginfo_t decoding.
92 * Enhanced PF_NETLINK decoding.
93 * Updated CLOCK_* constants
94 (addresses Fedora bug #1088455).
95 * Added new syscall entries to match Linux 3.16.
98 * Added shmat and shmdt to the set of memory mapping related syscalls.
99 * Fixed detaching from stopped processes.
100 * Fixed fanotify_mark decoding on 32bit architectures.
101 * Fixed offset decoding in preadv and pwritev syscalls.
102 * Fixed select decoding for glibc in _FORTIFY_SOURCE mode.
103 * Fixed decoding of epoll_ctl syscall with EPOLL_CTL_DEL argument.
104 * Fixed build when <sys/ptrace.h> and <linux/ptrace.h> conflict
105 (addresses Fedora bug #993384).
106 * Miscellaneous corrections in the manual page.
107 (Addresses Debian bug #725987).
109 Noteworthy changes in release 4.8 (2013-06-03)
110 ==============================================
112 * Changes in behavior
113 * In case of normal strace termination, when the trace output is
114 redirected to a pipe, strace now closes it and waits for the pipe
115 process termination before exit.
118 * Implemented tracing using PTRACE_SEIZE API (when available).
119 * Implemented more reliable PTRACE_GETREGSET-based process personality
120 detection on x86-64 and x32 (when available).
121 * Added -e trace=memory option for tracing memory mapping related syscalls.
122 * Documented -b option.
123 * Allowed exit status messages to be suppressed by giving -q option twice.
124 * Added AArch64 architecture support
125 (addresses Debian bug #693074 and Fedora bug #969858).
126 * Added support for OpenRISC 1000, Meta, and Xtensa architectures.
127 * Added tilegx personality support for Tile.
128 * Enhanced support of NOMMU architectures.
129 * Enhanced decoding of getdents, mmap, perf_event_open, ptrace, and
131 * Added new syscall entries to match Linux 3.9.
132 * Regenerated the list of common ioctl names from Linux 3.9.
133 * Updated the list of errno constants.
134 * Updated lists of AF_*, MADV_*, MAP_*, MSG_*, MS_*, PF_*, PR_*,
135 PTRACE_O_*, and TCP_* constants.
136 * Implemented decoding of UBI ioctls.
137 * Removed redundant "*32" ioctl names.
140 * Fixed ERESTARTNOINTR leaking to userspace on ancient kernels
141 (addresses Fedora bug #659382).
142 * Fixed kernel release string parsing
143 (addresses Debian bug #702309).
144 * Fixed decoding of *xattr syscalls
145 (addresses Fedora bug #885233).
146 * Fixed handling of files with 64-bit inode numbers by 32-bit strace
147 (addresses Fedora bug #912790).
148 * Fixed tracing forks on SPARC.
149 * Fixed decoding of fadvise64, fallocate, ftruncate64, io_submit, pread,
150 preadv, pwrite, pwritev, readahead, sigaltstack, sync_file_range, sysctl,
151 and truncate64 syscalls.
152 * Fixed categories of multiple syscalls on most of supported architectures.
153 * Fixed decoding of non-native 32-bit personality recv[m]msg syscalls.
154 * Fixed decoding of multiple 32-bit personality syscalls on x32.
155 * Fixed decoding of long long syscall arguments on ARM, MIPS/o32, PowerPC,
156 S390x, and Tile architectures.
157 * Fixed semtimedop decoding on S390x.
158 * Fixed sram_alloc decoding on Blackfin.
159 * Fixed build when process_vm_readv is a stab.
160 * Fixed build with older versions of libaio.h.
162 Noteworthy changes in release 4.7 (2012-05-02)
163 ==============================================
165 * Changes in behavior
166 * strace no longer suspends waitpid until there is a child
167 for waitpid'ing process to collect status from.
168 * strace no longer detaches from a tracee which is supposed
170 * strace now issues a new message: "+++ exited with EXITCODE +++"
171 which shows exact moment strace got exit notification,
172 analogous to existing "+++ killed by SIG +++" message.
175 * Added x32 personality support (x86_64 architecture).
176 * Added -y and -P options to print file descriptor paths and
177 filter by those paths.
178 * Added -I option to control strace interactivity.
179 * Allowed -p option to take comma or whitespace-separated list of PIDs.
180 * Added strace_log_merge script helper to merge timestamped "strace -ff"
182 * Implemented decoding of clock_adjtime, get_robust_list, migrate_pages,
183 preadv, prlimit64, process_vm_readv, process_vm_writev, pwritev,
184 recvmmsg, recvmsg, rt_tgsigqueueinfo, sendmmsg, setns, set_robust_list,
185 sched_rr_get_interval, splice, syslog, tee and vmsplice syscalls.
186 * Enhanced decoding of capget, capset, getrlimit, flistxattr, io_submit,
187 listxattr, setrlimit and swapon syscalls.
188 * Implemented decoding of loop and mtd ioctls.
189 * Added syscall entries for new linux syscalls.
190 * Added syscall entries for direct socket system calls on powerpc.
191 * Updated the list of errno constants.
192 * Updated lists of MSG_*, STA_*, and TCP_* constants.
193 * Regenerated the list of ioctl names from Linux 3.3.
194 * Enhanced switching between processes with different personalities.
195 * Enhanced signals reporting by using short signal names.
196 * Made ERESTART* messages more descriptive.
197 * Made parsing of numbers from strings more robust.
198 * Added support for compat_statfs64 and statfs64.f_flags.
199 * Changed read of data blocks to use single process_vm_readv syscall
200 (when available) instead of several PTRACE_PEEKDATA operations.
201 * Changed read of registers on x86 and x86-64 to use single PTRACE_GETREGS
202 operation instead of several PTRACE_PEEKUSER operations.
203 * Applied various optimizations to make strace work faster.
206 * Implemented proper handling of real SIGTRAPs on kernels supporting
207 PTRACE_O_TRACESYSGOOD.
208 (Addresses Fedora bug #162774).
209 * Fixed sockaddr_un.sun_path name in decoded output.
210 (Addresses Debian bug #554946).
211 * Fixed to avoid potential core file clobbering on exit.
212 (Addresses Debian bug #656398).
213 * Fixed a typo in documentation.
214 (Addresses Debian bug #653309).
215 * Fixed decoding of timer id returned by timer_create.
216 * Fixed epoll_create1, epoll_wait and epoll_pwait decoding.
217 * Fixed *at syscalls flags decoding.
218 * Fixed ARM EABI 64-bit syscall's arguments decoding.
219 * Fixed semtimedop decoding on s390.
220 * Fixed osf_sigprocmask decoding on alpha.
221 * Fixed ipc and socket subcall decoding on several architectures.
222 * Corrected syscall entries for epoll_pwait, epoll_create, epoll_ctl,
223 epoll_wait, mincore, mlockall, prctl, reboot, sendfile, sendfile64,
224 sendmsg, sgetmask, ssetmask, swapon, tgkill and tkill syscalls.
225 * Corrected io_* syscall entries on ARM.
226 * Fixed PID prefix printing in "strace -oLOG -ff -p1 -p2 -p3" case.
227 * Fixed logging of unfinished lines in "strace -oLOG -ff" case.
228 * Fixed build when libaio-devel is not available.
229 * Fixed configure checks for PTRACE_* constants.
230 * Fixed compilation warnings remained on several architectures.
233 * Removed all non-Linux code. After years of neglect, that dead code
234 just hampered further strace development.
235 * Linux kernel >= 2.6.18 is recommended. Older versions might still
236 work but they haven't been thoroughly tested with this release.
238 Noteworthy changes in release 4.6 (2011-03-15)
239 ==============================================
241 * Changes in behavior
242 * Print diagnostic information about changes in personality mode to
243 standard error instead of standard output.
246 * Implemented a new method of following clone, fork, and vfork
247 syscalls using the Linux kernel's explicit facilities for tracing
248 creation of threads and child processes.
249 * Implemented CLONE_PARENT and CLONE_UNTRACED flags handling.
250 * Implemented decoding of TLS syscalls on m68k.
251 * Implemented biarch support on powerpc64.
252 * Implemented biarch support for getrlimit() and setrlimit().
253 * Implemented decoding of struct ucred in getsockopt SO_PEERCRED.
254 * Implemented SOL_SCTP socket options decoding.
255 * Added HDIO_* ioctl names.
256 (Addresses Debian bug #450953).
257 * Added LOOP_* ioctl names.
258 * Updated lists of CLOCK_*, CLONE_*, MS_*, and SOL_* constants
259 to match Linux 2.6.37.
260 * Updated the list of IPPROTO_* constants to match netinet/in.h.
261 * Implemented decoding of HDIO_* and BLK* ioctls.
262 * Added MicroBlaze architecture support.
263 * Added new syscall entries to match Linux 2.6.37.
264 * Regenerated list of ioctl names from Linux 2.6.37.
265 * Enhanced signal notification decoding.
266 * Documented -C and -D options.
269 * Fixed fetching syscall arguments on m68k.
270 * Fixed an error when judging whether a process has children.
271 * Fixed get/set_robust_list syscall numbers for powerpc.
272 * Fixed a corner case in printing clone flags.
273 * Fixed cross-compiling issues.
274 * Fixed build issues on powerpc64, SH and SPARC.
275 * Fixed syscall flags of fstatat*, mmap, mmap2, fadvise64*, swapoff,
276 fgetxattr, flistxattr, fremovexattr, epoll_create, fallocate,
277 fanotify_init, and fanotify_mark syscalls.
278 * Fixed decoding of get[ug]id, gete[ug]id and setfs[ug]id return values.
279 * Fixed biarch support in IO dumping.
280 * Fixed raw exit_group decoding.
281 * Fixed decoding of file descriptors on 64-bit architectures.
282 * Fixed a corner case in waitpid handling.
283 (Addresses Red Hat bug #663547).
284 * Fixed stat64 decoding on mips
285 (Addresses Debian bug #599028).
286 * Fixed misleading italics in the manual page.
287 (Addresses Debian bug #589323).
289 Noteworthy changes in release 4.5.20 (2010-04-13)
290 =================================================
293 * Implemented decoding of new linux syscalls: inotify_init1, recvmmsg.
294 * Implemented basic decoding of new linux syscalls: preadv, pwritev,
295 rt_tgsigqueueinfo, perf_event_open.
296 * Enhanced decoding of recently added syscalls on non-x86 architectures
297 by replacing a bare decoder with elaborate parsers enabled earlier
299 * Implemented -C option to combine regular and -c output.
300 (Addresses Debian bug #466196)
301 * Enhanced decoding of mbind and mremap syscalls.
302 * Enhanced SOL_PACKET socket options decoding.
303 * Regenerated list of ioctl names from linux 2.6.33.
304 * Added TILE architecture support.
307 * Fixed build with Linux kernel headers 2.6.32-rc5+.
308 (Addresses Debian bug #560516 and Fedora bug #539044)
309 * Fixed build on mips.
310 * Fixed handling of Linux systems without struct statfs64.
311 * Fixed reporting signal mask by sigreturn on powerpc.
312 * Fixed potential stack buffer overflow in select decoder.
313 (Addresses Fedora bug #556678)
314 * Corrected msgsnd indirect ipccall decoding.
315 * Corrected decoding of 64bit syscalls.
316 (Addresses Debian bug #570603)
317 * Corrected getsockopt decoding on architectures where
318 sizeof(long) > sizeof(int).
319 (Addresses Debian bug #494844)
320 * Corrected decoding of epoll_pwait.
321 (Addresses Debian bug #513014)
322 * Corrected handling of killed threads.
324 Noteworthy changes in release 4.5.19 (2009-10-21)
325 =================================================
327 * Changes in behavior
328 * When command exits, strace now exits with the same exit status.
329 If command is terminated by a signal, strace terminates itself
330 with the same signal, so that strace can be used as a wrapper
331 process transparent to the invoking parent process.
332 When using -p option, the exit status of strace is zero unless
333 there was an unexpected error in doing the tracing.
334 (Addresses Fedora bug #105371 and Debian bug #37665)
337 * Implemented decoding of new Linux syscalls: accept4, dup3,
338 epoll_create1, eventfd2, inotify_init1, pipe2, signalfd4.
339 * Implemented decoding of socket type flags introduced in Linux 2.6.27.
340 * Implemented decoding of accept4 socketcall.
341 * Enhanced prctl decoding.
342 * Enhanced nanosleep decoding.
343 * Enhanced ptrace decoding.
344 * Enhanced futex decoding.
345 * Enhanced CAP_* decoding.
346 * Enhanced SIOCS* ioctls decoding.
347 * Enhanced fcntl F_* flags decoding.
348 * Enhanced semop/semtimedop decoding.
349 * Updated ARM architecture support.
350 * Added Blackfin architecture support.
351 * Added AVR32 architecture support.
352 * Added CRIS architecture support.
353 * Made strace detect when traced process suddenly disappeared.
356 * Fixed syscall numbers for tee and sync_file_range.
357 (Addresses Debian bug #503124)
358 * Fixed several bugs in strings decoder, including potential heap
360 (Addresses Fedora bugs #470529, #478324 and #511035)
361 * Marked sendfile(2) as a network syscall.
362 (Addresses Debian bug #509499)
363 * Fixed accept(2) decoding.
364 (Addresses Debian bug #507573)
365 * Fixed sigtimedwait(2) decoding.
366 * Fixed build on ARM EABI.
367 (Addresses Debian bugs #520084 and #535564, and Fedora bug #507576)
368 * Fixed display of 32-bit fcntl(F_SETLK) on 64-bit architectures.
369 (Addresses Red Hat bug #471169)
370 * Fixed display of 32-bit argv array on 64-bit architectures.
371 (Addresses Fedora bug #519480)
372 * Fixed display of 32-bit struct sigaction on 64-bit architectures.
373 * Fixed HPPA architecture support.
374 (Addresses Debian bugs #437928 and #546619)
379 * Support new Linux/PPC system call subpage_prot and PROT_SAO flag.
380 * In sigaction system call, display sa_flags value along with SIG_DFL/SIG_IGN.
385 * -F is now deprecated, -f has traced vfork too on Linux for a long time now.
386 * Print O_CLOEXEC, MSG_CMSG_CLOEXEC flag bits.
387 * Improved output for prctl system call on Linux.
388 * Improved support for Linux/ARM.
389 * SA_NOMASK is now spelled SA_NODEFER, and SA_ONESHOT is spelled SA_RESETHAND.
394 * Improved output for delete_module, futex, and mbind system calls on Linux.
395 * Improved output for SG_IO ioctls on Linux.
396 * Support new Linux system calls move_pages, utimensat, signalfd, timerfd,
397 eventfd, getcpu, epoll_pwait.
402 * Several biarch improvements.
403 * Improved output for adjtimex, sysctl, quotactl, mount, umount.
404 * Support new Linux system calls *at, inotify*, pselect6, ppoll and unshare.
409 * Accept numeric system calls in -e.
414 * Introduce "-e trace=desc".
419 * Better x86-64 support for IA32 processes.
420 * Update PowerPC system calls.
421 * Better printing for Linux aio system calls.
425 * Quick fix release for build issues.
426 * One fix for Linux/ARM system call table.
431 * Print fault address for SIGSEGV/SIGBUS signals when available.
436 * Improve socket ioctl printing.
437 * Update Linux/IA64 syscall list.
438 * Fix Linux/x86-64 syscall argument extraction for 32-bit processes.
439 * Improve mount flags printing.
440 * Support symbolic printing of x86_64 arch_prctl parameters.
445 * Update syscall tables for Alpha, ARM, HPPA.
446 * Support new Linux syscalls mbind, set_mempolicy, get_mempolicy, waitid.
447 * Support Linux syscalls fadvise64, fadvise64_64, and epoll_*.
448 * Improve ioctl command name matching.
449 * Print RTC_* ioctl structure contents.
450 * Support newer RLIMIT_* values.
451 * Print struct cmsghdr details in sendmsg.
456 * Print attribute values in *xattr system calls on Linux.
457 * Include pread and pwrite calls in -e read and -e write tracing.
458 * Update SO_* and IP_* value lists and add IPV6_* values for socket options.
459 * Print clock_t values symbolically in Linux clock_* system calls.
463 * Bug fixes, Linux ioctl updates.
464 * David Miller contributed support for Linux/SPARC64.
472 * Update Linux ioctl lists.
473 * Update PF_* and AF_* value lists.
474 * The 4.5.3 -p behavior for NPTL threads applies only under -f, and got fixed.
479 * On Linux using NPTL threads, -p will now attach to all threads in a process.
480 * Handle new mq_* system calls in Linux 2.6.6 and later.
485 * Report some new VM_* bit values on Linux.
486 * Better output for Linux sched_* system calls.
491 * Display multiple ioctl name matches on Linux.
495 * New port to AMD's x86-64 architecture. One strace binary can
496 handle both new x86-64 and old i386 processes.
497 * Fixed support for LFS64 calls.
498 * New switch -E to add/remove environment variables for the command.
499 * Merged s390/s390x port.
500 * Trace an unbounded number of processes.
501 * Handle numerous new system calls in Linux 2.5, and new threads semantics.
502 * Fixed bugs with attach/detach leaving things stopped.
503 * Fixed traced process seeing ECHILD despite live, traced children
504 in waitpid calls with WNOHANG.
505 * Stuart Menefy contributed a port to Linux/SH.
506 * Stephen Thomas contributed a port to Linux/SH64.
507 * Many other bug fixes.
511 * Fix Linux/ia64 support, looks like someone renamed a few things on us
512 * Fix the ioctl setup for Linux, turned out it did not really work.
513 Improve the ioctl extracter as well so we decode some more ones.
517 * compile fixes for Linux/mips
521 * Linux ia64 and hppa ports added
522 * The usual Linux syscall updates (includes 32bit uid/gid support),
523 * Linux ioctl list updated
524 * Support IPv6 scope ids
525 * FreeBSD/i386 port added
526 * UnixWare and Solaris updates
527 * Better support for tracing multithreaded processes in Linux
531 * Compiles on glibc2.0 systems again
532 * Linux/S390 port added
533 * The usual Linux syscall updates
534 * we can follow fork on arm now
538 * Linux/MIPS port added
539 * Lots of Linux updates again
540 * Improved IPv6 support
546 * Compiles on glibc2.0 systems again
550 * Get stat structure properly on Linux 64bit archs
551 * Personalities work again
552 * Compile correctly on SunOS again
558 * Linux (ultra)sparc fixes
565 * add support for more Linux architectures (powerpc, sparc, arm)
566 * support lots more Linux syscalls
567 * fix signal handling
568 * add IPX and IPIP support
569 * check stray syscall after execv
570 * fix hanging children
572 Changes in version 3.1
573 ======================
576 * Linux 68k is supported
577 * Linux alpha is supported
578 * configure is upgraded to autoconf 2.x
579 * using -f in combination with -e now works correctly
580 * output can be piped to a program
581 * tracing setuid programs works better
582 * it is now reasonable to install strace setuid to root in some circumstances
583 * new useful tracing names like file and process to trace whole
584 classes of system calls, e.g. -efile traces all system calls that
585 take a file name as an argument
586 * IPC calls on SunOS 4.1.x are decoded
587 * Linux program memory is reliably dereferenced
588 * Linux decodes at least the name of all syscalls as of pre2.0.4
589 * various cosmetic changes and bug fixes
591 Changes from versions 2.x to version 3.0
592 ========================================
594 * filename arguments are neither abbreviated nor stringified
595 * string arguments are now true C strings using octal instead of hex by default
596 * preprocessor constants are never shortened (e.g. was RDONLY => now O_RDONLY)
597 * by default the output for multiple processes now goes into one file
598 * all structures, vectors, bitsets, etc. use consistent output formats
599 * the -c option now means count calls, -i does what the old -c used to do
601 New Features in version 3.0
602 ===========================
604 * non-ascii strings can be optionally printed entirely in hex
605 * the output format is readable when mutiple processes are generating output
606 * exit values are printed in an alignment column
607 * is is possible to suppress messages about attaching and detaching
608 * various tracing features can be enabled on a per syscall/signal/desc basis
609 * selective tracing of syscalls
610 * selective printing of syscall structures
611 * selective abbreviation of long structures on a per syscall basis
612 * selective printing of raw syscall arguments and results
613 * selective tracing of signals
614 * selective dumping of all I/O read from file descriptors
615 * selective dumping of all I/O written to file descriptors
616 * optional counting of time, calls, and errors for each syscall