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           valgrind [valgrind-options] [your-program] [your-program-options]


           Valgrind is a flexible program for debugging and profiling Linux
           executables. It consists of a core, which provides a synthetic CPU in
           software, and a series of debugging and profiling tools. The
           architecture is modular, so that new tools can be created easily and
           without disturbing the existing structure.
           Some of the options described below work with all Valgrind tools, and
           some only work with a few or one. The section MEMCHECK OPTIONS and
           those below it describe tool-specific options.
           This manual page covers only basic usage and options. For more
           comprehensive information, please see the HTML documentation on your
           system: $INSTALL/share/doc/valgrind/html/index.html, or online:


           The single most important option.
           --tool=<toolname> [default: memcheck]
               Run the Valgrind tool called toolname, e.g. Memcheck, Cachegrind,


           These options work with all tools.
           -h --help
               Show help for all options, both for the core and for the selected
               tool. If the option is repeated it is equivalent to giving
               Same as --help, but also lists debugging options which usually are
               only of use to Valgrind's developers.
               Show the version number of the Valgrind core. Tools can have their
               own version numbers. There is a scheme in place to ensure that
               tools only execute when the core version is one they are known to
               work with. This was done to minimise the chances of strange
               problems arising from tool-vs-core version incompatibilities.
           -q, --quiet
               Run silently, and only print error messages. Useful if you are
               running regression tests or have some other automated test
           -v, --verbose
               Be more verbose. Gives extra information on various aspects of your
               This option only has an effect when --trace-children=yes is
               specified. It allows for some children to be skipped. The option
               takes a comma separated list of patterns for the names of child
               executables that Valgrind should not trace into. Patterns may
               include the metacharacters ?  and *, which have the usual meaning.
               This can be useful for pruning uninteresting branches from a tree
               of processes being run on Valgrind. But you should be careful when
               using it. When Valgrind skips tracing into an executable, it
               doesn't just skip tracing that executable, it also skips tracing
               any of that executable's child processes. In other words, the flag
               doesn't merely cause tracing to stop at the specified executables
               -- it skips tracing of entire process subtrees rooted at any of the
               specified executables.
               This is the same as --trace-children-skip, with one difference: the
               decision as to whether to trace into a child process is made by
               examining the arguments to the child process, rather than the name
               of its executable.
           --child-silent-after-fork=<yes|no> [default: no]
               When enabled, Valgrind will not show any debugging or logging
               output for the child process resulting from a fork call. This can
               make the output less confusing (although more misleading) when
               dealing with processes that create children. It is particularly
               useful in conjunction with --trace-children=. Use of this option is
               also strongly recommended if you are requesting XML output
               (--xml=yes), since otherwise the XML from child and parent may
               become mixed up, which usually makes it useless.
           --vgdb=<no|yes|full> [default: yes]
               Valgrind will provide "gdbserver" functionality when --vgdb=yes or
               --vgdb=full is specified. This allows an external GNU GDB debugger
               to control and debug your program when it runs on Valgrind. See ???
               for a detailed description.
               If the embedded gdbserver is enabled but no gdb is currently being
               used, the ???  command line utility can send "monitor commands" to
               Valgrind from a shell. The Valgrind core provides a set of ???. A
               tool can optionally provide tool specific monitor commands, which
               are documented in the tool specific chapter.
               --vgdb=full incurs significant performance overheads.
           --vgdb-error=<number> [default: 999999999]
               Use this option when the Valgrind gdbserver is enabled with
               --vgdb=yes or --vgdb=full. Tools that report errors will wait for
               "number" errors to be reported before freezing the program and
               waiting for you to connect with GDB. It follows that a value of
               zero will cause the gdbserver to be started before your program is
               minutes, seconds and milliseconds.
           --log-fd=<number> [default: 2, stderr]
               Specifies that Valgrind should send all of its messages to the
               specified file descriptor. The default, 2, is the standard error
               channel (stderr). Note that this may interfere with the client's
               own use of stderr, as Valgrind's output will be interleaved with
               any output that the client sends to stderr.
               Specifies that Valgrind should send all of its messages to the
               specified file. If the file name is empty, it causes an abort.
               There are three special format specifiers that can be used in the
               file name.
               %p is replaced with the current process ID. This is very useful for
               program that invoke multiple processes. WARNING: If you use
               --trace-children=yes and your program invokes multiple processes OR
               your program forks without calling exec afterwards, and you don't
               use this specifier (or the %q specifier below), the Valgrind output
               from all those processes will go into one file, possibly jumbled
               up, and possibly incomplete.
               %q{FOO} is replaced with the contents of the environment variable
               FOO. If the {FOO} part is malformed, it causes an abort. This
               specifier is rarely needed, but very useful in certain
               circumstances (eg. when running MPI programs). The idea is that you
               specify a variable which will be set differently for each process
               in the job, for example BPROC_RANK or whatever is applicable in
               your MPI setup. If the named environment variable is not set, it
               causes an abort. Note that in some shells, the { and } characters
               may need to be escaped with a backslash.
               %% is replaced with %.
               If an % is followed by any other character, it causes an abort.
               Specifies that Valgrind should send all of its messages to the
               specified port at the specified IP address. The port may be
               omitted, in which case port 1500 is used. If a connection cannot be
               made to the specified socket, Valgrind falls back to writing output
               to the standard error (stderr). This option is intended to be used
               in conjunction with the valgrind-listener program. For further
               details, see the commentary in the manual.


           These options are used by all tools that can report errors, e.g.
           Memcheck, but not Cachegrind.
           --xml=<yes|no> [default: no]
               When enabled, the important parts of the output (e.g. tool error
               option works with Memcheck, Helgrind, DRD and SGcheck. The output
               format is specified in the file
               docs/internals/xml-output-protocol4.txt in the source tree for
               Valgrind 3.5.0 or later.
               The recommended options for a GUI to pass, when requesting XML
               output, are: --xml=yes to enable XML output, --xml-file to send the
               XML output to a (presumably GUI-selected) file, --log-file to send
               the plain text output to a second GUI-selected file,
               --child-silent-after-fork=yes, and -q to restrict the plain text
               output to critical error messages created by Valgrind itself. For
               example, failure to read a specified suppressions file counts as a
               critical error message. In this way, for a successful run the text
               output file will be empty. But if it isn't empty, then it will
               contain important information which the GUI user should be made
               aware of.
           --xml-fd=<number> [default: -1, disabled]
               Specifies that Valgrind should send its XML output to the specified
               file descriptor. It must be used in conjunction with --xml=yes.
               Specifies that Valgrind should send its XML output to the specified
               file. It must be used in conjunction with --xml=yes. Any %p or %q
               sequences appearing in the filename are expanded in exactly the
               same way as they are for --log-file. See the description of
               --log-file for details.
               Specifies that Valgrind should send its XML output the specified
               port at the specified IP address. It must be used in conjunction
               with --xml=yes. The form of the argument is the same as that used
               by --log-socket. See the description of --log-socket for further
               Embeds an extra user comment string at the start of the XML output.
               Only works when --xml=yes is specified; ignored otherwise.
           --demangle=<yes|no> [default: yes]
               Enable/disable automatic demangling (decoding) of C++ names.
               Enabled by default. When enabled, Valgrind will attempt to
               translate encoded C++ names back to something approaching the
               original. The demangler handles symbols mangled by g++ versions
               2.X, 3.X and 4.X.
               An important fact about demangling is that function names mentioned
               in suppressions files should be in their mangled form. Valgrind
               does not demangle function names when searching for applicable
               suppressions, because to do otherwise would make suppression file
               contents dependent on the state of Valgrind's demangling machinery,
               and also slow down suppression matching.
               When enabled, Valgrind stops reporting errors after 10,000,000 in
               total, or 1,000 different ones, have been seen. This is to stop the
               error tracking machinery from becoming a huge performance overhead
               in programs with many errors.
           --error-exitcode=<number> [default: 0]
               Specifies an alternative exit code to return if Valgrind reported
               any errors in the run. When set to the default value (zero), the
               return value from Valgrind will always be the return value of the
               process being simulated. When set to a nonzero value, that value is
               returned instead, if Valgrind detects any errors. This is useful
               for using Valgrind as part of an automated test suite, since it
               makes it easy to detect test cases for which Valgrind has reported
               errors, just by inspecting return codes.
           --show-below-main=<yes|no> [default: no]
               By default, stack traces for errors do not show any functions that
               appear beneath main because most of the time it's uninteresting C
               library stuff and/or gobbledygook. Alternatively, if main is not
               present in the stack trace, stack traces will not show any
               functions below main-like functions such as glibc's
               __libc_start_main. Furthermore, if main-like functions are present
               in the trace, they are normalised as (below main), in order to make
               the output more deterministic.
               If this option is enabled, all stack trace entries will be shown
               and main-like functions will not be normalised.
           --fullpath-after=<string> [default: don't show source paths]
               By default Valgrind only shows the filenames in stack traces, but
               not full paths to source files. When using Valgrind in large
               projects where the sources reside in multiple different
               directories, this can be inconvenient.  --fullpath-after provides a
               flexible solution to this problem. When this option is present, the
               path to each source file is shown, with the following all-important
               caveat: if string is found in the path, then the path up to and
               including string is omitted, else the path is shown unmodified.
               Note that string is not required to be a prefix of the path.
               For example, consider a file named
               /home/janedoe/blah/src/foo/bar/xyzzy.c. Specifying
               --fullpath-after=/home/janedoe/blah/src/ will cause Valgrind to
               show the name as foo/bar/xyzzy.c.
               Because the string is not required to be a prefix,
               --fullpath-after=src/ will produce the same output. This is useful
               when the path contains arbitrary machine-generated characters. For
               example, the path /my/build/dir/C32A1B47/blah/src/foo/xyzzy can be
               pruned to foo/xyzzy using --fullpath-after=/blah/src/.
               If you simply want to see the full path, just specify an empty
               string: --fullpath-after=. This isn't a special case, merely a
           --gen-suppressions=<yes|no|all> [default: no]
               When set to yes, Valgrind will pause after every error shown and
               print the line:
                       ---- Print suppression ? --- [Return/N/n/Y/y/C/c] ----
               The prompt's behaviour is the same as for the --db-attach option
               (see below).
               If you choose to, Valgrind will print out a suppression for this
               error. You can then cut and paste it into a suppression file if you
               don't want to hear about the error in the future.
               When set to all, Valgrind will print a suppression for every
               reported error, without querying the user.
               This option is particularly useful with C++ programs, as it prints
               out the suppressions with mangled names, as required.
               Note that the suppressions printed are as specific as possible. You
               may want to common up similar ones, by adding wildcards to function
               names, and by using frame-level wildcards. The wildcarding
               facilities are powerful yet flexible, and with a bit of careful
               editing, you may be able to suppress a whole family of related
               errors with only a few suppressions.
               Sometimes two different errors are suppressed by the same
               suppression, in which case Valgrind will output the suppression
               more than once, but you only need to have one copy in your
               suppression file (but having more than one won't cause problems).
               Also, the suppression name is given as <insert a suppression name
               here>; the name doesn't really matter, it's only used with the -v
               option which prints out all used suppression records.
           --db-attach=<yes|no> [default: no]
               When enabled, Valgrind will pause after every error shown and print
               the line:
                       ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ----
               Pressing Ret, or N Ret or n Ret, causes Valgrind not to start a
               debugger for this error.
               Pressing Y Ret or y Ret causes Valgrind to start a debugger for the
               program at this point. When you have finished with the debugger,
               quit from it, and the program will continue. Trying to continue
               from inside the debugger doesn't work.
               Note: if you use GDB, more powerful debugging support is provided
               by the --vgdb= yes or full value. This activates Valgrind's
               internal gdbserver, which provides more-or-less full GDB-style
               /usr/bin/gdb. Using this command, you can specify some alternative
               command to invoke the debugger you want to use.
               The command string given can include one or instances of the %p and
               %f expansions. Each instance of %p expands to the PID of the
               process to be debugged and each instance of %f expands to the path
               to the executable for the process to be debugged.
               Since <command> is likely to contain spaces, you will need to put
               this entire option in quotes to ensure it is correctly handled by
               the shell.
           --input-fd=<number> [default: 0, stdin]
               When using --db-attach=yes or --gen-suppressions=yes, Valgrind will
               stop so as to read keyboard input from you when each error occurs.
               By default it reads from the standard input (stdin), which is
               problematic for programs which close stdin. This option allows you
               to specify an alternative file descriptor from which to read input.
           --dsymutil=no|yes [no]
               This option is only relevant when running Valgrind on Mac OS X.
               Mac OS X uses a deferred debug information (debuginfo) linking
               scheme. When object files containing debuginfo are linked into a
               .dylib or an executable, the debuginfo is not copied into the final
               file. Instead, the debuginfo must be linked manually by running
               dsymutil, a system-provided utility, on the executable or .dylib.
               The resulting combined debuginfo is placed in a directory alongside
               the executable or .dylib, but with the extension .dSYM.
               With --dsymutil=no, Valgrind will detect cases where the .dSYM
               directory is either missing, or is present but does not appear to
               match the associated executable or .dylib, most likely because it
               is out of date. In these cases, Valgrind will print a warning
               message but take no further action.
               With --dsymutil=yes, Valgrind will, in such cases, automatically
               run dsymutil as necessary to bring the debuginfo up to date. For
               all practical purposes, if you always use --dsymutil=yes, then
               there is never any need to run dsymutil manually or as part of your
               applications's build system, since Valgrind will run it as
               Valgrind will not attempt to run dsymutil on any executable or
               library in /usr/, /bin/, /sbin/, /opt/, /sw/, /System/, /Library/
               or /Applications/ since dsymutil will always fail in such
               situations. It fails both because the debuginfo for such
               pre-installed system components is not available anywhere, and also
               because it would require write privileges in those directories.
               Be careful when using --dsymutil=yes, since it will cause
               pre-existing .dSYM directories to be silently deleted and
               well. However, if your program allocates large structures on the
               stack, this heuristic will be fooled, and Memcheck will
               subsequently report large numbers of invalid stack accesses. This
               option allows you to change the threshold to a different value.
               You should only consider use of this option if Valgrind's debug
               output directs you to do so. In that case it will tell you the new
               threshold you should specify.
               In general, allocating large structures on the stack is a bad idea,
               because you can easily run out of stack space, especially on
               systems with limited memory or which expect to support large
               numbers of threads each with a small stack, and also because the
               error checking performed by Memcheck is more effective for
               heap-allocated data than for stack-allocated data. If you have to
               use this option, you may wish to consider rewriting your code to
               allocate on the heap rather than on the stack.
           --main-stacksize=<number> [default: use current 'ulimit' value]
               Specifies the size of the main thread's stack.
               To simplify its memory management, Valgrind reserves all required
               space for the main thread's stack at startup. That means it needs
               to know the required stack size at startup.
               By default, Valgrind uses the current "ulimit" value for the stack
               size, or 16 MB, whichever is lower. In many cases this gives a
               stack size in the range 8 to 16 MB, which almost never overflows
               for most applications.
               If you need a larger total stack size, use --main-stacksize to
               specify it. Only set it as high as you need, since reserving far
               more space than you need (that is, hundreds of megabytes more than
               you need) constrains Valgrind's memory allocators and may reduce
               the total amount of memory that Valgrind can use. This is only
               really of significance on 32-bit machines.
               On Linux, you may request a stack of size up to 2GB. Valgrind will
               stop with a diagnostic message if the stack cannot be allocated.
               --main-stacksize only affects the stack size for the program's
               initial thread. It has no bearing on the size of thread stacks, as
               Valgrind does not allocate those.
               You may need to use both --main-stacksize and --max-stackframe
               together. It is important to understand that --main-stacksize sets
               the maximum total stack size, whilst --max-stackframe specifies the
               largest size of any one stack frame. You will have to work out the
               --main-stacksize value for yourself (usually, if your applications
               segfaults). But Valgrind will tell you the needed --max-stackframe
               size, if necessary.
               value must be greater than or equal to the default, less than or
               equal to 4096, and must be a power of two.


           These options apply to all tools, as they affect certain obscure
           workings of the Valgrind core. Most people won't need to use these.
           --smc-check=<none|stack|all|all-non-file> [default: stack]
               This option controls Valgrind's detection of self-modifying code.
               If no checking is done, if a program executes some code, then
               overwrites it with new code, and executes the new code, Valgrind
               will continue to execute the translations it made for the old code.
               This will likely lead to incorrect behaviour and/or crashes.
               Valgrind has four levels of self-modifying code detection: no
               detection, detect self-modifying code on the stack (which is used
               by GCC to implement nested functions), detect self-modifying code
               everywhere, and detect self-modifying code everywhere except in
               file-backed mappings. Note that the default option will catch the
               vast majority of cases. The main case it will not catch is programs
               such as JIT compilers that dynamically generate code and
               subsequently overwrite part or all of it. Running with all will
               slow Valgrind down noticeably. Running with none will rarely speed
               things up, since very little code gets put on the stack for most
               programs. The VALGRIND_DISCARD_TRANSLATIONS client request is an
               alternative to --smc-check=all that requires more programmer effort
               but allows Valgrind to run your program faster, by telling it
               precisely when translations need to be re-made.
               --smc-check=all-non-file provides a cheaper but more limited
               version of --smc-check=all. It adds checks to any translations that
               do not originate from file-backed memory mappings. Typical
               applications that generate code, for example JITs in web browsers,
               generate code into anonymous mmaped areas, whereas the "fixed" code
               of the browser always lives in file-backed mappings.
               --smc-check=all-non-file takes advantage of this observation,
               limiting the overhead of checking to code which is likely to be JIT
               Some architectures (including ppc32, ppc64 and ARM) require
               programs which create code at runtime to flush the instruction
               cache in between code generation and first use. Valgrind observes
               and honours such instructions. Hence, on ppc32/Linux, ppc64/Linux
               and ARM/Linux, Valgrind always provides complete, transparent
               support for self-modifying code. It is only on platforms such as
               x86/Linux, AMD64/Linux, x86/Darwin and AMD64/Darwin that you need
               to use this option.
           --read-var-info=<yes|no> [default: no]
               When enabled, Valgrind will read information about variable types
               and locations from DWARF3 debug info. This slows Valgrind down and
               makes it use more memory, but for the tools that can take advantage
               And here are the same errors with --read-var-info=yes:
                   ==15522== Uninitialised byte(s) found during client check request
                   ==15522==    at 0x400633: croak (varinfo1.c:28)
                   ==15522==    by 0x4006B2: main (varinfo1.c:55)
                   ==15522==  Location 0x60103b is 0 bytes inside global_i2[7],
                   ==15522==  a global variable declared at varinfo1.c:41
                   ==15522== Uninitialised byte(s) found during client check request
                   ==15522==    at 0x400633: croak (varinfo1.c:28)
                   ==15522==    by 0x4006BC: main (varinfo1.c:56)
                   ==15522==  Location 0x7fefffefc is 0 bytes inside local var "local"
                   ==15522==  declared at varinfo1.c:46, in frame #1 of thread 1
           --vgdb-poll=<number> [default: 5000]
               As part of its main loop, the Valgrind scheduler will poll to check
               if some activity (such as an external command or some input from a
               gdb) has to be handled by gdbserver. This activity poll will be
               done after having run the given number of basic blocks (or slightly
               more than the given number of basic blocks). This poll is quite
               cheap so the default value is set relatively low. You might further
               decrease this value if vgdb cannot use ptrace system call to
               interrupt Valgrind if all threads are (most of the time) blocked in
               a system call.
           --vgdb-shadow-registers=no|yes [default: no]
               When activated, gdbserver will expose the Valgrind shadow registers
               to GDB. With this, the value of the Valgrind shadow registers can
               be examined or changed using GDB. Exposing shadow registers only
               works with GDB version 7.1 or later.
           --vgdb-prefix=<prefix> [default: /tmp/vgdb-pipe]
               To communicate with gdb/vgdb, the Valgrind gdbserver creates 3
               files (2 named FIFOs and a mmap shared memory file). The prefix
               option controls the directory and prefix for the creation of these
           --run-libc-freeres=<yes|no> [default: yes]
               This option is only relevant when running Valgrind on Linux.
               The GNU C library (, which is used by all programs, may
               allocate memory for its own uses. Usually it doesn't bother to free
               that memory when the program ends--there would be no point, since
               the Linux kernel reclaims all process resources when a process
               exits anyway, so it would just slow things down.
               The glibc authors realised that this behaviour causes leak
               checkers, such as Valgrind, to falsely report leaks in glibc, when
               a leak check is done at exit. In order to avoid this, they provided
               a routine called __libc_freeres specifically to make glibc release
               all memory it has allocated. Memcheck therefore tries to run
               __libc_freeres at exit.
               ?   lax-ioctls: Be very lax about ioctl handling; the only
                   assumption is that the size is correct. Doesn't require the
                   full buffer to be initialized when writing. Without this, using
                   some device drivers with a large number of strange ioctl
                   commands becomes very tiresome.
               ?   enable-inner: Enable some special magic needed when the program
                   being run is itself Valgrind.
               ?   fuse-compatible: Enable special handling for certain system
                   calls that may block in a FUSE file-system. This may be
                   necessary when running Valgrind on a multi-threaded program
                   that uses one thread to manage a FUSE file-system and another
                   thread to access that file-system.
               Handle system calls and ioctls arising from minor variants of the
               default kernel for this platform. This is useful for running on
               hacked kernels or with kernel modules which support nonstandard
               ioctls, for example. Use with caution. If you don't understand what
               this option does then you almost certainly don't need it. Currently
               known variants are:
               ?   bproc: Support the sys_broc system call on x86. This is for
                   running on BProc, which is a minor variant of standard Linux
                   which is sometimes used for building clusters.
           --show-emwarns=<yes|no> [default: no]
               When enabled, Valgrind will emit warnings about its CPU emulation
               in certain cases. These are usually not interesting.
               When a shared object whose soname matches sonamepatt is loaded into
               the process, examine all the text symbols it exports. If none of
               those match fnnamepatt, print an error message and abandon the run.
               This makes it possible to ensure that the run does not continue
               unless a given shared object contains a particular function name.
               Both sonamepatt and fnnamepatt can be written using the usual ?
               and * wildcards. For example: ":**:foo?bar". You may use
               characters other than a colon to separate the two patterns. It is
               only important that the first character and the separator character
               are the same. For example, the above example could also be written
               "Q**Qfoo?bar". Multiple
                --require-text-symbol flags are allowed, in which case shared
               objects that are loaded into the process will be checked against
               all of them.
               The purpose of this is to support reliable usage of marked-up
               libraries. For example, suppose we have a version of GCC's
      which has been marked up with annotations to support
           see the list, use the --help-debug option.


           --leak-check=<no|summary|yes|full> [default: summary]
               When enabled, search for memory leaks when the client program
               finishes. If set to summary, it says how many leaks occurred. If
               set to full or yes, it also gives details of each individual leak.
           --show-possibly-lost=<yes|no> [default: yes]
               When disabled, the memory leak detector will not show "possibly
               lost" blocks.
           --leak-resolution=<low|med|high> [default: high]
               When doing leak checking, determines how willing Memcheck is to
               consider different backtraces to be the same for the purposes of
               merging multiple leaks into a single leak report. When set to low,
               only the first two entries need match. When med, four entries have
               to match. When high, all entries need to match.
               For hardcore leak debugging, you probably want to use
               --leak-resolution=high together with --num-callers=40 or some such
               large number.
               Note that the --leak-resolution setting does not affect Memcheck's
               ability to find leaks. It only changes how the results are
           --show-reachable=<yes|no> [default: no]
               When disabled, the memory leak detector only shows "definitely
               lost" and "possibly lost" blocks. When enabled, the leak detector
               also shows "reachable" and "indirectly lost" blocks. (In other
               words, it shows all blocks, except suppressed ones, so --show-all
               would be a better name for it.)
           --undef-value-errors=<yes|no> [default: yes]
               Controls whether Memcheck reports uses of undefined value errors.
               Set this to no if you don't want to see undefined value errors. It
               also has the side effect of speeding up Memcheck somewhat.
           --track-origins=<yes|no> [default: no]
               Controls whether Memcheck tracks the origin of uninitialised
               values. By default, it does not, which means that although it can
               tell you that an uninitialised value is being used in a dangerous
               way, it cannot tell you where the uninitialised value came from.
               This often makes it difficult to track down the root problem.
               When set to yes, Memcheck keeps track of the origins of all
               uninitialised values. Then, when an uninitialised value error is
               reported, Memcheck will try to show the origin of the value. An
               origin can be one of the following four places: a heap block, a
               stack allocation, a client request, or miscellaneous other sources
               (eg, a call to brk).
               running more slowly.
               Accuracy: Memcheck tracks origins quite accurately. To avoid very
               large space and time overheads, some approximations are made. It is
               possible, although unlikely, that Memcheck will report an incorrect
               origin, or not be able to identify any origin.
               Note that the combination --track-origins=yes and
               --undef-value-errors=no is nonsensical. Memcheck checks for and
               rejects this combination at startup.
           --partial-loads-ok=<yes|no> [default: no]
               Controls how Memcheck handles word-sized, word-aligned loads from
               addresses for which some bytes are addressable and others are not.
               When yes, such loads do not produce an address error. Instead,
               loaded bytes originating from illegal addresses are marked as
               uninitialised, and those corresponding to legal addresses are
               handled in the normal way.
               When no, loads from partially invalid addresses are treated the
               same as loads from completely invalid addresses: an illegal-address
               error is issued, and the resulting bytes are marked as initialised.
               Note that code that behaves in this way is in violation of the the
               ISO C/C++ standards, and should be considered broken. If at all
               possible, such code should be fixed. This option should be used
               only as a last resort.
           --freelist-vol=<number> [default: 20000000]
               When the client program releases memory using free (in C) or delete
               (C++), that memory is not immediately made available for
               re-allocation. Instead, it is marked inaccessible and placed in a
               queue of freed blocks. The purpose is to defer as long as possible
               the point at which freed-up memory comes back into circulation.
               This increases the chance that Memcheck will be able to detect
               invalid accesses to blocks for some significant period of time
               after they have been freed.
               This option specifies the maximum total size, in bytes, of the
               blocks in the queue. The default value is twenty million bytes.
               Increasing this increases the total amount of memory used by
               Memcheck but may detect invalid uses of freed blocks which would
               otherwise go undetected.
           --freelist-big-blocks=<number> [default: 1000000]
               When making blocks from the queue of freed blocks available for
               re-allocation, Memcheck will in priority re-circulate the blocks
               with a size greater or equal to --freelist-big-blocks. This ensures
               that freeing big blocks (in particular freeing blocks bigger than
               --freelist-vol) does not immediately lead to a re-circulation of
               all (or a lot of) the small blocks in the free list. In other
               words, this option increases the likelihood to discover dangling
               You may also need to use this option when working with GCC 3.X or
               4.X on 32-bit PowerPC Linux. This is because GCC generates code
               which occasionally accesses below the stack pointer, particularly
               for floating-point to/from integer conversions. This is in
               violation of the 32-bit PowerPC ELF specification, which makes no
               provision for locations below the stack pointer to be accessible.
               Any ranges listed in this option (and multiple ranges can be
               specified, separated by commas) will be ignored by Memcheck's
               addressability checking.
               Fills blocks allocated by malloc, new, etc, but not by calloc, with
               the specified byte. This can be useful when trying to shake out
               obscure memory corruption problems. The allocated area is still
               regarded by Memcheck as undefined -- this option only affects its
               Fills blocks freed by free, delete, etc, with the specified byte
               value. This can be useful when trying to shake out obscure memory
               corruption problems. The freed area is still regarded by Memcheck
               as not valid for access -- this option only affects its contents.


           --I1=<size>,<associativity>,<line size>
               Specify the size, associativity and line size of the level 1
               instruction cache.
           --D1=<size>,<associativity>,<line size>
               Specify the size, associativity and line size of the level 1 data
           --LL=<size>,<associativity>,<line size>
               Specify the size, associativity and line size of the last-level
           --cache-sim=no|yes [yes]
               Enables or disables collection of cache access and miss counts.
           --branch-sim=no|yes [no]
               Enables or disables collection of branch instruction and
               misprediction counts. By default this is disabled as it slows
               Cachegrind down by approximately 25%. Note that you cannot specify
               --cache-sim=no and --branch-sim=no together, as that would leave
               Cachegrind with no information to collect.
               Write the profile data to file rather than to the default output
               file, cachegrind.out.<pid>. The %p and %q format specifiers can be
               This specifies that event counting should be performed at source
               line granularity. This allows source annotation for sources which
               are compiled with debug information (-g).
           --dump-instr=<no|yes> [default: no]
               This specifies that event counting should be performed at
               per-instruction granularity. This allows for assembly code
               annotation. Currently the results can only be displayed by
           --compress-strings=<no|yes> [default: yes]
               This option influences the output format of the profile data. It
               specifies whether strings (file and function names) should be
               identified by numbers. This shrinks the file, but makes it more
               difficult for humans to read (which is not recommended in any
           --compress-pos=<no|yes> [default: yes]
               This option influences the output format of the profile data. It
               specifies whether numerical positions are always specified as
               absolute values or are allowed to be relative to previous numbers.
               This shrinks the file size.
           --combine-dumps=<no|yes> [default: no]
               When enabled, when multiple profile data parts are to be generated
               these parts are appended to the same output file. Not recommended.
           --dump-every-bb=<count> [default: 0, never]
               Dump profile data every count basic blocks. Whether a dump is
               needed is only checked when Valgrind's internal scheduler is run.
               Therefore, the minimum setting useful is about 100000. The count is
               a 64-bit value to make long dump periods possible.
               Dump when entering function.
               Zero all costs when entering function.
               Dump when leaving function.
           --instr-atstart=<yes|no> [default: yes]
               Specify if you want Callgrind to start simulation and profiling
               from the beginning of the program. When set to no, Callgrind will
               not be able to collect any information, including calls, but it
               will have at most a slowdown of around 4, which is the minimum
               Valgrind overhead. Instrumentation can be interactively enabled via
               callgrind_control -i on.
               Note that the resulting call graph will most probably not contain
               main, but will contain all the functions executed after
                1. Zero event counters before entering the program part you want
                   to profile, and dump the event counters to a file after leaving
                   that program part.
                2. Switch on/off collection state as needed to only see event
                   counters happening while inside of the program part you want to
               The second option can be used if the program part you want to
               profile is called many times. Option 1, i.e. creating a lot of
               dumps is not practical here.
               Collection state can be toggled at entry and exit of a given
               function with the option --toggle-collect. If you use this option,
               collection state should be disabled at the beginning. Note that the
               specification of --toggle-collect implicitly sets
               Collection state can be toggled also by inserting the client
               request CALLGRIND_TOGGLE_COLLECT ; at the needed code positions.
               Toggle collection on entry/exit of function.
           --collect-jumps=<no|yes> [default: no]
               This specifies whether information for (conditional) jumps should
               be collected. As above, callgrind_annotate currently is not able to
               show you the data. You have to use KCachegrind to get jump arrows
               in the annotated code.
           --collect-systime=<no|yes> [default: no]
               This specifies whether information for system call times should be
           --collect-bus=<no|yes> [default: no]
               This specifies whether the number of global bus events executed
               should be collected. The event type "Ge" is used for these events.
           --cache-sim=<yes|no> [default: no]
               Specify if you want to do full cache simulation. By default, only
               instruction read accesses will be counted ("Ir"). With cache
               simulation, further event counters are enabled: Cache misses on
               instruction reads ("I1mr"/"ILmr"), data read accesses ("Dr") and
               related cache misses ("D1mr"/"DLmr"), data write accesses ("Dw")
               and related cache misses ("D1mw"/"DLmw"). For more information, see
           --branch-sim=<yes|no> [default: no]
               Specify if you want to do branch prediction simulation. Further
               event counters are enabled: Number of executed conditional branches
               and related predictor misses ("Bc"/"Bcm"), executed indirect jumps
           --track-lockorders=no|yes [default: yes]
               When enabled (the default), Helgrind performs lock order
               consistency checking. For some buggy programs, the large number of
               lock order errors reported can become annoying, particularly if
               you're only interested in race errors. You may therefore find it
               helpful to disable lock order checking.
           --history-level=none|approx|full [default: full]
               --history-level=full (the default) causes Helgrind collects enough
               information about "old" accesses that it can produce two stack
               traces in a race report -- both the stack trace for the current
               access, and the trace for the older, conflicting access.
               Collecting such information is expensive in both speed and memory,
               particularly for programs that do many inter-thread synchronisation
               events (locks, unlocks, etc). Without such information, it is more
               difficult to track down the root causes of races. Nonetheless, you
               may not need it in situations where you just want to check for the
               presence or absence of races, for example, when doing regression
               testing of a previously race-free program.
               --history-level=none is the opposite extreme. It causes Helgrind
               not to collect any information about previous accesses. This can be
               dramatically faster than --history-level=full.
               --history-level=approx provides a compromise between these two
               extremes. It causes Helgrind to show a full trace for the later
               access, and approximate information regarding the earlier access.
               This approximate information consists of two stacks, and the
               earlier access is guaranteed to have occurred somewhere between
               program points denoted by the two stacks. This is not as useful as
               showing the exact stack for the previous access (as
               --history-level=full does), but it is better than nothing, and it
               is almost as fast as --history-level=none.
           --conflict-cache-size=N [default: 1000000]
               This flag only has any effect at --history-level=full.
               Information about "old" conflicting accesses is stored in a cache
               of limited size, with LRU-style management. This is necessary
               because it isn't practical to store a stack trace for every single
               memory access made by the program. Historical information on not
               recently accessed locations is periodically discarded, to free up
               space in the cache.
               This option controls the size of the cache, in terms of the number
               of different memory addresses for which conflicting access
               information is stored. If you find that Helgrind is showing race
               errors with only one stack instead of the expected two stacks, try
               increasing this value.
               Controls whether DRD detects data races on stack variables.
               Verifying stack variables is disabled by default because most
               programs do not share stack variables over threads.
           --exclusive-threshold=<n> [default: off]
               Print an error message if any mutex or writer lock has been held
               longer than the time specified in milliseconds. This option enables
               the detection of lock contention.
           --join-list-vol=<n> [default: 10]
               Data races that occur between a statement at the end of one thread
               and another thread can be missed if memory access information is
               discarded immediately after a thread has been joined. This option
               allows to specify for how many joined threads memory access
               information should be retained.
            --first-race-only=<yes|no> [default: no]
               Whether to report only the first data race that has been detected
               on a memory location or all data races that have been detected on a
               memory location.
            --free-is-write=<yes|no> [default: no]
               Whether to report races between accessing memory and freeing
               memory. Enabling this option may cause DRD to run slightly slower.
               ?   Don't enable this option when using custom memory allocators
                   that use the VG_USERREQ__MALLOCLIKE_BLOCK and
                   VG_USERREQ__FREELIKE_BLOCK because that would result in false
               ?   Don't enable this option when using reference-counted objects
                   because that will result in false positives, even when that
                   code has been annotated properly with ANNOTATE_HAPPENS_BEFORE
                   and ANNOTATE_HAPPENS_AFTER. See e.g. the output of the
                   following command for an example: valgrind --tool=drd
                   --free-is-write=yes drd/tests/annotate_smart_pointer.
            --report-signal-unlocked=<yes|no> [default: yes]
               Whether to report calls to pthread_cond_signal and
               pthread_cond_broadcast where the mutex associated with the signal
               through pthread_cond_wait or pthread_cond_timed_waitis not locked
               at the time the signal is sent. Sending a signal without holding a
               lock on the associated mutex is a common programming error which
               can cause subtle race conditions and unpredictable behavior. There
               exist some uncommon synchronization patterns however where it is
               safe to send a signal without holding a lock on the associated
           --segment-merging=<yes|no> [default: yes]
               Controls segment merging. Segment merging is an algorithm to limit
           --shared-threshold=<n> [default: off]
               Print an error message if a reader lock has been held longer than
               the specified time (in milliseconds). This option enables the
               detection of lock contention.
           --show-confl-seg=<yes|no> [default: yes]
               Show conflicting segments in race reports. Since this information
               can help to find the cause of a data race, this option is enabled
               by default. Disabling this option makes the output of DRD more
           --show-stack-usage=<yes|no> [default: no]
               Print stack usage at thread exit time. When a program creates a
               large number of threads it becomes important to limit the amount of
               virtual memory allocated for thread stacks. This option makes it
               possible to observe how much stack memory has been used by each
               thread of the the client program. Note: the DRD tool itself
               allocates some temporary data on the client thread stack. The space
               necessary for this temporary data must be allocated by the client
               program when it allocates stack memory, but is not included in
               stack usage reported by DRD.
           --trace-addr=<address> [default: none]
               Trace all load and store activity for the specified address. This
               option may be specified more than once.
           --trace-alloc=<yes|no> [default: no]
               Trace all memory allocations and deallocations. May produce a huge
               amount of output.
           --trace-barrier=<yes|no> [default: no]
               Trace all barrier activity.
           --trace-cond=<yes|no> [default: no]
               Trace all condition variable activity.
           --trace-fork-join=<yes|no> [default: no]
               Trace all thread creation and all thread termination events.
           --trace-hb=<yes|no> [default: no]
               Trace execution of the ANNOTATE_HAPPENS_BEFORE(),
           --trace-mutex=<yes|no> [default: no]
               Trace all mutex activity.
           --trace-rwlock=<yes|no> [default: no]
               Trace all reader-writer lock activity.
           --trace-semaphore=<yes|no> [default: no]
               Trace all semaphore activity.
               Specifies whether stack profiling should be done. This option slows
               Massif down greatly, and so is off by default. Note that Massif
               assumes that the main stack has size zero at start-up. This is not
               true, but doing otherwise accurately is difficult. Furthermore,
               starting at zero better indicates the size of the part of the main
               stack that a user program actually has control over.
           --pages-as-heap=<yes|no> [default: no]
               Tells Massif to profile memory at the page level rather than at the
               malloc'd block level. See above for details.
           --depth=<number> [default: 30]
               Maximum depth of the allocation trees recorded for detailed
               snapshots. Increasing it will make Massif run somewhat more slowly,
               use more memory, and produce bigger output files.
               Functions specified with this option will be treated as though they
               were a heap allocation function such as malloc. This is useful for
               functions that are wrappers to malloc or new, which can fill up the
               allocation trees with uninteresting information. This option can be
               specified multiple times on the command line, to name multiple
               Note that the named function will only be treated this way if it is
               the top entry in a stack trace, or just below another function
               treated this way. For example, if you have a function malloc1 that
               wraps malloc, and malloc2 that wraps malloc1, just specifying
               --alloc-fn=malloc2 will have no effect. You need to specify
               --alloc-fn=malloc1 as well. This is a little inconvenient, but the
               reason is that checking for allocation functions is slow, and it
               saves a lot of time if Massif can stop looking through the stack
               trace entries as soon as it finds one that doesn't match rather
               than having to continue through all the entries.
               Note that C++ names are demangled. Note also that overloaded C++
               names must be written in full. Single quotes may be necessary to
               prevent the shell from breaking them up. For example:
                   --alloc-fn='operator new(unsigned, std::nothrow_t const&)'
               Any direct heap allocation (i.e. a call to malloc, new, etc, or a
               call to a function named by an --alloc-fn option) that occurs in a
               function specified by this option will be ignored. This is mostly
               useful for testing purposes. This option can be specified multiple
               times on the command line, to name multiple functions.
               Any realloc of an ignored block will also be ignored, even if the
               realloc call does not occur in an ignored function. This avoids the
               possibility of negative heap sizes if ignored blocks are shrunk
               memory allocation size exceeds the previous peak by at least 1.0%.
               This is because there can be many local allocation peaks along the
               way, and doing a detailed snapshot for every one would be expensive
               and wasteful, as all but one of them will be later discarded. This
               inaccuracy can be changed (even to 0.0%) via this option, but
               Massif will run drastically slower as the number approaches zero.
           --time-unit=<i|ms|B> [default: i]
               The time unit used for the profiling. There are three
               possibilities: instructions executed (i), which is good for most
               cases; real (wallclock) time (ms, i.e. milliseconds), which is
               sometimes useful; and bytes allocated/deallocated on the heap
               and/or stack (B), which is useful for very short-run programs, and
               for testing purposes, because it is the most reproducible across
               different machines.
           --detailed-freq=<n> [default: 10]
               Frequency of detailed snapshots. With --detailed-freq=1, every
               snapshot is detailed.
           --max-snapshots=<n> [default: 100]
               The maximum number of snapshots recorded. If set to N, for all
               programs except very short-running ones, the final number of
               snapshots will be between N/2 and N.
           --massif-out-file=<file> [default: massif.out.%p]
               Write the profile data to file rather than to the default output
               file, massif.out.<pid>. The %p and %q format specifiers can be used
               to embed the process ID and/or the contents of an environment
               variable in the name, as is the case for the core option --log-


           <xi:include></xi:include>.SH "BBV OPTIONS"
           --bb-out-file=<name> [default: bb.out.%p]
               This option selects the name of the basic block vector file. The %p
               and %q format specifiers can be used to embed the process ID and/or
               the contents of an environment variable in the name, as is the case
               for the core option --log-file.
           --pc-out-file=<name> [default: pc.out.%p]
               This option selects the name of the PC file. This file holds
               program counter addresses and function name info for the various
               basic blocks. This can be used in conjunction with the basic block
               vector file to fast-forward via function names instead of just
               instruction counts. The %p and %q format specifiers can be used to
               embed the process ID and/or the contents of an environment variable
               in the name, as is the case for the core option --log-file.
           --interval-size=<number> [default: 100000000]
               This option selects the size of the interval to use. The default is


           --basic-counts=<no|yes> [default: yes]
               When enabled, Lackey prints the following statistics and
               information about the execution of the client program:
                1. The number of calls to the function specified by the --fnname
                   option (the default is main). If the program has had its
                   symbols stripped, the count will always be zero.
                2. The number of conditional branches encountered and the number
                   and proportion of those taken.
                3. The number of superblocks entered and completed by the program.
                   Note that due to optimisations done by the JIT, this is not at
                   all an accurate value.
                4. The number of guest (x86, amd64, ppc, etc.) instructions and IR
                   statements executed. IR is Valgrind's RISC-like intermediate
                   representation via which all instrumentation is done.
                5. Ratios between some of these counts.
                6. The exit code of the client program.
           --detailed-counts=<no|yes> [default: no]
               When enabled, Lackey prints a table containing counts of loads,
               stores and ALU operations, differentiated by their IR types. The IR
               types are identified by their IR name ("I1", "I8", ... "I128",
               "F32", "F64", and "V128").
           --trace-mem=<no|yes> [default: no]
               When enabled, Lackey prints the size and address of almost every
               memory access made by the program. See the comments at the top of
               the file lackey/lk_main.c for details about the output format, how
               it works, and inaccuracies in the address trace. Note that this
               option produces immense amounts of output.
           --trace-superblocks=<no|yes> [default: no]
               When enabled, Lackey prints out the address of every superblock (a
               single entry, multiple exit, linear chunk of code) executed by the
               program. This is primarily of interest to Valgrind developers. See
               the comments at the top of the file lackey/lk_main.c for details
               about the output format. Note that this option produces large
               amounts of output.
           --fnname=<name> [default: main]
               Changes the function for which calls are counted when
               --basic-counts=yes is specified.


           cg_annotate(1), callgrind_annotate(1), callgrind_control(1),

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