Provided by: mono-runtime-common_4.6.2.7+dfsg-1ubuntu1_amd64 bug


       mono - Mono's ECMA-CLI native code generator (Just-in-Time and Ahead-of-Time)


       mono [options] file [arguments...]

       mono-sgen [options] file [arguments...]


       mono  is a runtime implementation of the ECMA Common Language Infrastructure.  This can be
       used to run ECMA and .NET applications.

       The runtime contains a native code  generator  that  transforms  the  Common  Intermediate
       Language into native code.

       The  code  generator  can operate in two modes: just in time compilation (JIT) or ahead of
       time compilation (AOT).  Since code can be dynamically loaded, the runtime environment and
       the JIT are always present, even if code is compiled ahead of time.

       The  runtime loads the specified file and optionally passes the arguments to it.  The file
       is an ECMA assembly.  They typically have a .exe or .dll extension.

       The runtime provides a number of  configuration  options  for  running  applications,  for
       developing and debugging, and for testing and debugging the runtime itself.

       The mono command uses the Boehm conservative garbage collector while the mono-sgen command
       uses a moving and generational garbage collector.


       On Unix-based systems, Mono provides a mechanism to emulate the Windows-style file access,
       this  includes  providing  a case insensitive view of the file system, directory separator
       mapping (from \ to /) and stripping the drive letters.

       This functionality is enabled by setting the MONO_IOMAP environment  variable  to  one  of
       all, drive and case.

       See the description for MONO_IOMAP in the environment variables section for more details.


       The following options are available:

       --aot, --aot[=options]
              This  option is used to precompile the CIL code in the specified assembly to native
              code.  The generated code is stored in a file with the extension  .so.   This  file
              will  be  automatically  picked  up  by  the runtime when the assembly is executed.
              Ahead-of-Time compilation is most useful if you use  it  in  combination  with  the
              -O=all,-shared flag which enables all of the optimizations in the code generator to
              be performed.  Some of those  optimizations  are  not  practical  for  Just-in-Time
              compilation  since  they  might be very time consuming.  Unlike the .NET Framework,
              Ahead-of-Time compilation will not generate domain independent code:  it  generates
              the   same  code  that  the  Just-in-Time  compiler  would  produce.    Since  most
              applications use a single domain, this is fine.    If  you  want  to  optimize  the
              generated  code  for use in multi-domain applications, consider using the -O=shared
              flag.  This pre-compiles the methods, but the original assembly is  still  required
              to execute as this one contains the metadata and exception information which is not
              available on the generated file.  When precompiling code, you might want to compile
              with  all  optimizations (-O=all).  Pre-compiled code is position independent code.
              Pre compilation is just a mechanism to reduce startup time, increase  code  sharing
              across  multiple  mono processes and avoid just-in-time compilation program startup
              costs.  The original assembly must still be present, as the metadata  is  contained
              there.   AOT  code  typically  can  not be moved from one computer to another (CPU-
              specific optimizations that are detected at runtime) so you should not try to  move
              the   pre-generated   assemblies   or  package  the  pre-generated  assemblies  for
              deployment.  A few options are available as a parameter to the --aot  command  line
              option.   The options are separated by commas, and more than one can be specified:

                     The AOT compiler will emit a (ELF only) library initializer to automatically
                     register the aot compiled module with the runtime.  This is only  useful  in
                     static mode

                     Instructs  the  AOT  compiler  to  output assembly code instead of an object

                     If specified, forces the generated AOT files to  be  bound  to  the  runtime
                     version  of the compiling Mono.   This will prevent the AOT files from being
                     consumed  by  a  different  Mono  runtime.   full  This  is   currently   an
                     experimental  feature  as  it  is  not  complete.   This  instructs  Mono to
                     precompile code that has historically not been precompiled with AOT.

                     This instructs the AOT code generator to output certain data constructs into
                     a separate file.   This can reduce the executable images some five to twenty
                     percent.   Developers need to then ship the resulting aotdata as a  resource
                     and   register   a   hook   to   load  the  data  on  demand  by  using  the
                     mono_install_load_aot_data_hook method.

                     When this option is specified, P/Invoke methods are invoked directly instead
                     of going through the operating system symbol lookup operation.

                     Same for the llvm tools 'opt' and 'llc'.

                     Instructs  the AOT compiler to generate offline sequence points .msym files.
                     The generated .msym files will be stored into a subfolder of <PATH> named as
                     the compilation AOTID.

                     Use  the  GNU style target triple <TRIPLE> to determine some code generation
                     options, i.e.  --mtriple=armv7-linux-gnueabi will generate code that targets
                     ARMv7.  This  is  currently only supported by the ARM backend. In LLVM mode,
                     this triple is passed on to the LLVM llc compiler.

                     When compiling in full aot mode, the IMT trampolines must be  precreated  in
                     the  AOT  image.   You  can  add  additional  method  trampolines  with this
                     argument.  Defaults to 128.

                     Instructs the AOT compiler to not output any debugging information.

                     This prevents the AOT compiler from generating a direct calls to  a  method.
                     The  AOT compiler usually generates direct calls for certain methods that do
                     not require going through the PLT (for example, methods that  are  known  to
                     not  require  a hook like a static constructor) or call into simple internal

                     Instructs the AOT compiler to emit DWARF debugging  information.  When  used
                     together  with  the  nodebug  option,  only  DWARF  debugging information is
                     emitted, but not the information that can be used at runtime.

                     When compiling in full aot mode, the generic  sharing  trampolines  must  be
                     precreated in the AOT image.  You can add additional method trampolines with
                     this argument.  Defaults to 1024.

                     When compiling in full aot mode, the method trampolines must  be  precreated
                     in  the  AOT  image.   You  can  add additional method trampolines with this
                     argument.  Defaults to 1024.

                     Instructs the AOT compiler to save the output to the specified file.

                     If the AOT compiler cannot compile a method for any  reason,  enabling  this
                     flag will output the skipped methods to the console.

                     Override  the  value  of  a  static  readonly  field.  Usually,  during  JIT
                     compilation, the static constructor is ran eagerly, so the value of a static
                     readonly field is known at compilation time and the compiler can do a number
                     of optimizations based on it. During AOT, instead,  the  static  constructor
                     can't  be  ran,  so this option can be used to set the value of such a field
                     and enable the same set of optimizations.  Type can be any of i1, i2, i4 for
                     integers  of  the  respective  sizes  (in bytes).  Note that signed/unsigned
                     numbers do not matter here, just the  storage  size.   This  option  can  be
                     specified  multiple  times and it doesn't prevent the static constructor for
                     the type defining the field to execute  with  the  usual  rules  at  runtime
                     (hence possibly computing a different value for the field).

                     Instructs the AOT compiler to keep temporary files.

                     This  instructs  the  compiler  to generate sequence point checks that allow
                     Mono's soft debugger to debug applications even on systems where it  is  not
                     possible   to   set   breakpoints   or  to  single  step  (certain  hardware
                     configurations like the cell phones and video gaming consoles).

              static Create an ELF object file (.o) or .s file which  can  be  statically  linked
                     into  an  executable  when  embedding  the mono runtime. When this option is
                     used, the object file needs to be registered with the embedded runtime using
                     the  mono_aot_register_module  function  which  takes  as  its  argument the
                     mono_aot_module_<ASSEMBLY NAME>_info global symbol from the object file:

                     extern void *mono_aot_module_hello_info;

                     mono_aot_register_module (mono_aot_module_hello_info);

              stats  Print various stats collected during AOT compilation.

                     This is an experimental option for the AOT compiler to use multiple  threads
                     when compiling the methods.

                     Prepends  <PREFIX>  to  the  name  of  tools  ran  by the AOT compiler, i.e.
                     'as'/'ld'. For example, --tool=prefix=arm-linux-gnueabi- will make  the  AOT
                     compiler run

                     Instructs the AOT compiler to emit debug symbol information.

              For more information about AOT, see:

              Currently  the only option supported by this command line argument is disable which
              disables the attach functionality.

       --config filename
              Load the specified configuration file instead of the default one(s).   The  default
              files  are  /etc/mono/config  and  ~/.mono/config  or  the  file  specified  in the
              MONO_CONFIG environment variable, if set.  See  the  mono-config(5)  man  page  for
              details on the format of this file.

              This  instructs the Mono runtime to start a debugging agent inside the Mono runtime
              and connect it to a client user interface will  control  the  Mono  process.   This
              option is typically used by IDEs, like the MonoDevelop IDE.

       The configuration is specified using one of more of the following options:

                     Use  this  option  to  specify  the IP address where your debugger client is
                     listening to.

                     Specifies the diagnostics log level for

                     Used to specify the file where the  log  will  be  stored,  it  defaults  to
                     standard output.

                     Defaults  to  no,  with the default option Mono will actively connect to the
                     host/port configured with the address option.  If you  set  it  to  'y',  it
                     instructs  the  Mono  runtime  to start debugging in server mode, where Mono
                     actively waits for the debugger front end to connect to  the  Mono  process.
                     Mono will print out to stdout the IP address and port where it is listening.

                     If  set to yes, Mono will call setpgid(0, 0) on startup, if that function is
                     available on the system. This is useful for ensuring that signals  delivered
                     to  a  process  that  is  executing  the  debuggee are not propagated to the
                     debuggee, e.g. when Ctrl-C sends SIGINT to the sdb tool.

                     Defaults to yes, with the default option Mono will suspend the vm on startup
                     until  it  connects  successfully to a debugger front end.  If you set it to
                     'n', in conjunction with server=y, it instructs the Mono runtime to  run  as
                     normal,  while  caching  metadata  to  send  to  the  debugger  front end on

                     This is used to  specify  the  transport  that  the  debugger  will  use  to
                     communicate.    It  must  be  specified  and  currently  requires this to be

              Configures the virtual machine  to  be  better  suited  for  desktop  applications.
              Currently  this  sets the GC system to avoid expanding the heap as much as possible
              at the expense of slowing down garbage collection a bit.

              This is an experimental flag that instructs the Mono runtime to  not  generate  any
              code  at  runtime  and  depend  exclusively  on  the code generated from using mono
              --aot=full previously.   This is useful for platforms that do  not  permit  dynamic
              code  generation.   Notice  that  this feature will abort execution at runtime if a
              codepath in your program, or Mono's  class  libraries  attempts  to  generate  code
              dynamically.   You  should test your software upfront and make sure that you do not
              use any dynamic features.

       --gc=boehm, --gc=sgen
              Selects the Garbage Collector engine for Mono to use,  Boehm  or  SGen.   Currently
              this  merely  ensures  that  you are running either the mono or mono-sgen commands.
              This flag can be set in the MONO_ENV_OPTIONS environment variable to force  all  of
              your child processes to use one particular kind of GC with the Mono runtime.

       --arch=32, --arch=64
              (Mac  OS X only): Selects the bitness of the Mono binary used, if available. If the
              binary used is already for the selected  bitness,  nothing  changes.  If  not,  the
              execution  switches  to a binary with the selected bitness suffix installed side by
              side  (for  example,  '/bin/mono  --arch=64'  will  switch  to  '/bin/mono64'   iff
              '/bin/mono' is a 32-bit build).

       --help, -h
              Displays usage instructions.

       --llvm If  the  Mono  runtime  has  been  compiled with LLVM support (not available in all
              configurations), Mono will use the LLVM optimization and code generation engine  to
              JIT   or   AOT   compile.    For   more   information,   consult:  http://www.mono-

              When using a Mono that has been compiled with  LLVM  support,  it  forces  Mono  to
              fallback to its JIT engine and not use the LLVM backend.

       --optimize=MODE, -O=MODE
              MODE  is a comma separated list of optimizations.  They also allow optimizations to
              be turned off by prefixing the optimization name with a minus  sign.   In  general,
              Mono has been tuned to use the default set of flags, before using these flags for a
              deployment setting, you might want to actually measure the benefits of using  them.
              The following optimization flags are implemented in the core engine:
                           abcrem     Array bound checks removal
                           all        Turn on all optimizations
                           aot        Usage of Ahead Of Time compiled code
                           branch     Branch optimizations
                           cfold      Constant folding
                           cmov       Conditional moves [arch-dependency]
                           deadce     Dead code elimination
                           consprop   Constant propagation
                           copyprop   Copy propagation
                           fcmov      Fast x86 FP compares [arch-dependency]
                           float32     Perform 32-bit float arithmetic using 32-bit operations
                           gshared    Enable generic code sharing.
                           inline     Inline method calls
                           intrins    Intrinsic method implementations
                           linears    Linear scan global reg allocation
                           leaf       Leaf procedures optimizations
                           loop       Loop related optimizations
                           peephole   Peephole postpass
                           precomp    Precompile all methods before executing Main
                           sched      Instruction scheduling
                           shared     Emit per-domain code
                           sse2       SSE2 instructions on x86 [arch-dependency]
                           tailc      Tail recursion and tail calls
              For example, to enable all the optimization but dead code elimination and inlining,
              you can use:
              The flags that are flagged with [arch-dependency] indicate that the given option if
              used  in combination with Ahead of Time compilation (--aot flag) would produce pre-
              compiled code that will depend on the current CPU and might not be safely moved  to
              another computer.

              The following optimizations are supported

                     Requests  that  the  runtime performn 32-bit floating point operations using
                     only 32-bits.   By default  the  Mono  runtime  tries  to  use  the  highest
                     precision  available  for  floating  point  operations, but while this might
                     render better results, the  code  might  run  slower.    This  options  also
                     affects the code generated by the LLVM backend.

              inline Controls  whether the runtime should attempt to inline (the default), or not
                     inline methods invocations

              Mono supports different runtime versions. The version used depends on  the  program
              that  is  being  run  or on its configuration file (named program.exe.config). This
              option can be used to override such autodetection, by forcing a  different  runtime
              version to be used. Note that this should only be used to select a later compatible
              runtime version than the one the program was compiled against. A typical  usage  is
              for running a 1.1 program on a 2.0 version:
                       mono --runtime=v2.0.50727 program.exe

       --security, --security=mode
              Activate  the  security manager, a currently experimental feature in Mono and it is
              OFF by default. The new code verifier can be enabled with this option as well.

              Using security without parameters is  equivalent  as  calling  it  with  the  "cas"

              The following modes are supported:

                     Enables    the    core-clr    security    system,    typically    used   for
                     Moonlight/Silverlight applications.  It provides  a  much  simpler  security
                     system  than  CAS,  see for
                     more details and links to the descriptions of this new system.

                     Enables the new verifier and performs basic verification for code  validity.
                     In  this  mode,  unsafe  code and P/Invoke are allowed. This mode provides a
                     better safety guarantee but it is still possible for managed code  to  crash

                     Enables  the  new  verifier and performs full verification of the code being
                     executed.  It only allows verifiable code to be executed.   Unsafe  code  is
                     not  allowed  but  P/Invoke  is.  This mode should not allow managed code to
                     crash mono.  The verification is not as strict as ECMA 335 standard in order
                     to stay compatible with the MS runtime.

              The  security  system  acts  on user code: code contained in mscorlib or the global
              assembly cache is always trusted.

              Configures  the  virtual  machine  to  be  better  suited  for  server   operations
              (currently, allows a heavier threadpool initialization).

              Verifies mscorlib and assemblies in the global assembly cache for valid IL, and all
              user code for IL verifiability.

              This is different from --security's verifiable or validil  in  that  these  options
              only  check  user  code  and  skip  mscorlib  and  assemblies located on the global
              assembly cache.

       -V, --version
              Prints JIT version information (system configuration,  release  number  and  branch
              names if available).


       The following options are used to help when developing a JITed application.

       --debug, --debug=OPTIONS
              Turns  on  the  debugging  mode  in  the runtime.  If an assembly was compiled with
              debugging information, it will produce line number information for stack traces.

              The optional OPTIONS argument is a  comma  separated  list  of  debugging  options.
              These  options are turned off by default since they generate much larger and slower
              code at runtime.

              The following options are supported:

              casts  Produces a detailed  error  when  throwing  a  InvalidCastException.    This
                     option  needs to be enabled as this generates more verbose code at execution

                     Disable some JIT optimizations which are usually only disabled when  running
                     inside  the  debugger.   This  can  be  helpful if you want to attach to the
                     running process with mdb.

              gdb    Generate and register debugging information with gdb. This is only supported
                     on some platforms, and only when using gdb 7.0 or later.

              Turns  on  profiling.   For  more information about profiling applications and code
              coverage see the sections "PROFILING" and "CODE COVERAGE" below.

       This option can be used multiple times, each time will load an
              additional profiler.   This allows developers to use modules that  extend  the  JIT
              through the Mono profiling interface.

              Shows  method  names  as they are invoked.  By default all methods are traced.  The
              trace can be customized to include or exclude methods, classes  or  assemblies.   A
              trace  expression is a comma separated list of targets, each target can be prefixed
              with a minus sign to turn off a particular target.  The words `program', `all'  and
              `disabled'  have  special  meaning.   `program'  refers  to  the main program being
              executed, and `all' means all the method calls.  The `disabled' option is  used  to
              start  up with tracing disabled.  It can be enabled at a later point in time in the
              program by sending the SIGUSR2 signal to the runtime.  Assemblies are specified  by
              their name, for example, to trace all calls in the System assembly, use:

                   mono --trace=System app.exe

              Classes  are  specified with the T: prefix.  For example, to trace all calls to the
              System.String class, use:

                   mono --trace=T:System.String app.exe

              And individual methods are referenced with the M: prefix, and the  standard  method

                   mono --trace=M:System.Console:WriteLine app.exe

              Exceptions can also be traced, it will cause a stack trace to be printed every time
              an exception of the specified type is thrown.  The exception type can be  specified
              with  or  without  the namespace, and to trace all exceptions, specify 'all' as the
              type name.

                   mono --trace=E:System.Exception app.exe

              As previously noted, various rules can be specified at once:

                   mono --trace=T:System.String,T:System.Random app.exe

              You can exclude pieces, the next example traces calls to System.String  except  for
              the System.String:Concat method.

                   mono --trace=T:System.String,-M:System.String:Concat

              You can trace managed to unmanaged transitions using the wrapper qualifier:

                   mono --trace=wrapper app.exe

              Finally, namespaces can be specified using the N: prefix:

                   mono --trace=N:System.Xml

              Don't  align  stack  frames on the x86 architecture.  By default, Mono aligns stack
              frames to 16 bytes on x86, so that local floating point and SIMD variables  can  be
              properly  aligned.   This  option  turns off the alignment, which usually saves one
              intruction per call, but might result in significantly  lower  floating  point  and
              SIMD performance.

              Generate  a JIT method map in a /tmp/ file. This file is then used, for
              example, by the perf tool included in recent Linux kernels.  Each line in the  file

                   HEXADDR HEXSIZE methodname

              Currently this option is only supported on Linux.


       The  maintainer  options  are  only  used  by those developing the runtime itself, and not
       typically of interest to runtime users or developers.

              This flag is used  by  the  automatic  optimization  bug  bisector.   It  takes  an
              optimization  flag and a filename of a file containing a list of full method names,
              one per line.  When it compiles one of the methods in the  file  it  will  use  the
              optimization  given,  in  addition to the optimizations that are otherwise enabled.
              Note that if the optimization is enabled by default, you  should  disable  it  with
              `-O`,  otherwise  it  will  just apply to every method, whether it's in the file or

       --break method
              Inserts   a   breakpoint   before   the   method    whose    name    is    `method'
              (namespace.class:methodname).   Use `Main' as method name to insert a breakpoint on
              the application's main method.  You can use it  also  with  generics,  for  example

              Inserts a breakpoint on exceptions.  This allows you to debug your application with
              a native debugger when an exception is thrown.

       --compile name
              This compiles a method (, this is used  for  testing  the
              compiler performance or to examine the output of the code generator.

              Compiles  all  the  methods  in  an  assembly.   This  is used to test the compiler
              performance or to examine the output of the code generator

       --graph=TYPE METHOD
              This generates a postscript file with a graph with the details about the  specified
              method  (   This  requires  `dot'  and  ghostview  to be
              installed (it expects Ghostview to be  called  "gv").   The  following  graphs  are
                        cfg        Control Flow Graph (CFG)
                        dtree      Dominator Tree
                        code       CFG showing code
                        ssa        CFG showing code after SSA translation
                        optcode    CFG showing code after IR optimizations
              Some graphs will only be available if certain optimizations are turned on.

              Instruct  the runtime on the number of times that the method specified by --compile
              (or all the methods if --compileall is used) to be  compiled.   This  is  used  for
              testing the code generator performance.

              Displays  information about the work done by the runtime during the execution of an

              Perform maintenance of the process shared data.   semdel  will  delete  the  global
              semaphore.  hps will list the currently used handles.

       -v, --verbose
              Increases  the  verbosity  level,  each  time it is listed, increases the verbosity
              level to include more information (including, for example,  a  disassembly  of  the
              native code produced, code selector info etc.).


       The  Mono  runtime  allows  external  processes  to  attach  to a running process and load
       assemblies into the running program.   To attach to the process,  a  special  protocol  is
       implemented in the Mono.Management assembly.

       With  this  support  it  is possible to load assemblies that have an entry point (they are
       created with -target:exe or -target:winexe) to be loaded and executed in the Mono process.

       The code is loaded into the root domain, and it starts execution on  the  special  runtime
       attach  thread.     The  attached  program  should create its own threads and return after

       This support allows for example debugging applications by having the csharp  shell  attach
       to running processes.


       The  mono  runtime  includes  a  profiler  that can be used to explore various performance
       related problems in your application.  The profiler is activated by passing the  --profile
       command line argument to the Mono runtime, the format is:


       Mono has a built-in profiler called 'default' (and is also the default if no arguments are
       specified), but developers can write custom profilers, see the section "CUSTOM  PROFILERS"
       for more details.

       If  a  profiler  is  not  specified, the default profiler is used.  The profiler_args is a
       profiler-specific string of options for the profiler itself.  The default profiler accepts
       the  following options 'alloc' to profile memory consumption by the application; 'time' to
       profile the time spent on each routine; 'jit' to collect time spent JIT-compiling  methods
       and  'stat'  to  perform  sample  statistical  profiling.   If no options are provided the
       default is 'alloc,time,jit'.

       By default the profile data is printed to stdout: to change this, use the  'file=filename'
       option to output the data to filename.  For example:

            mono --profile program.exe

       That  will  run  the  program  with  the  default profiler and will do time and allocation

            mono --profile=default:stat,alloc,file=prof.out program.exe

       Will do  sample statistical profiling and allocation profiling on program.exe. The profile
       data  is  put in prof.out.  Note that the statistical profiler has a very low overhead and
       should be the preferred profiler to use (for better output use the full path to  the  mono
       binary when running and make sure you have installed the addr2line utility that comes from
       the binutils package).


       This is the most advanced profiler.

       The Mono log profiler can be used to collect a lot of information about a program  running
       in  the Mono runtime.  This data can be used (both while the process is running and later)
       to do analyses of the program behaviour, determine resource usage, performance  issues  or
       even look for particular execution patterns.

       This  is  accomplished  by  logging  the  events  provided by the Mono runtime through the
       profiling interface and periodically writing them to a file which can be  later  inspected
       with the mprof-report(1) tool.

       More  information  about  how  to use the log profiler is available on the mprof-report(1)


       Mono provides a mechanism for loading other profiling modules which in the form of  shared
       libraries.   These  profiling  modules can hook up to various parts of the Mono runtime to
       gather information about the code being executed.

       To use a third party profiler you must pass the name of the profiler to Mono, like this:

            mono --profile=custom program.exe

       In the above sample Mono will load the user  defined  profiler  from  the  shared  library
       `'.   This  profiler  module must be on your dynamic linker library

       A list of other third party  profilers  is  available  from  Mono's  web  site  (www.mono-

       Custom profiles are written as shared libraries.  The shared library must be called `mono-' where `NAME' is the name of your profiler.

       For a sample of how to write your own custom profiler look in the Mono source tree for  in
       the samples/profiler.c.


       Mono  ships  with  a  code  coverage  module.   This module is activated by using the Mono
       --profile=cov option.   The  format  is:  --profile=cov[:assembly-name[/namespace]]  test-

       By  default code coverage will default to all the assemblies loaded, you can limit this by
       specifying the assembly name, for example to perform code coverage in the routines of your
       program  use,  for example the following command line limits the code coverage to routines
       in the "demo" assembly:

            mono --profile=cov:demo demo.exe

       Notice that the assembly-name does not include the extension.

       You can further restrict the code coverage output by specifying a namespace:

            mono --profile=cov:demo/My.Utilities demo.exe

       Which will only perform code coverage in the given assembly and namespace.

       Typical output looks like this:

            Not covered: Class:.ctor ()
            Not covered: Class:A ()
            Not covered: Driver:.ctor ()
            Not covered: Driver:method ()
            Partial coverage: Driver:Main ()
                 offset 0x000a

       The offsets displayed are IL offsets.

       A more powerful coverage tool is available in the module `monocov'.   See  the  monocov(1)
       man page for details.


       To debug managed applications, you can use the mdb command, a command line debugger.

       It  is  possible  to obtain a stack trace of all the active threads in Mono by sending the
       QUIT signal to Mono, you can do this from the command line, like this:

            kill -QUIT pid

       Where pid is the Process ID of the Mono process you want to  examine.   The  process  will
       continue running afterwards, but its state is not guaranteed.

       Important:  this  is  a last-resort mechanism for debugging applications and should not be
       used to monitor or probe a production application.  The integrity  of  the  runtime  after
       sending  this signal is not guaranteed and the application might crash or terminate at any
       given point afterwards.

       The --debug=casts option can be used to get more detailed  information  for  Invalid  Cast
       operations, it will provide information about the types involved.

       You  can  use  the  MONO_LOG_LEVEL  and MONO_LOG_MASK environment variables to get verbose
       debugging output about the execution of your application within Mono.

       The MONO_LOG_LEVEL environment variable if set, the logging level is changed  to  the  set
       value. Possible values are "error", "critical", "warning", "message", "info", "debug". The
       default value is "error". Messages with a logging level greater then or equal to  the  log
       level will be printed to stdout/stderr.

       Use "info" to track the dynamic loading of assemblies.

       Use the MONO_LOG_MASK environment variable to limit the extent of the messages you get: If
       set, the log mask is changed to  the  set  value.  Possible  values  are  "asm"  (assembly
       loader),  "type",  "dll"  (native library loader), "gc" (garbage collector), "cfg" (config
       file  loader),  "aot"  (precompiler),  "security"  (e.g.   Moonlight   CoreCLR   support),
       "threadpool"  (thread  pool  generic),  "io-threadpool" (thread pool I/O), "io-layer" (I/O
       layer - sockets, handles, shared memory etc) and  "all".   The  default  value  is  "all".
       Changing  the  mask value allows you to display only messages for a certain component. You
       can use multiple masks by comma separating them. For example to see config  file  messages
       and assembly loader messages set you mask to "asm,cfg".

       The following is a common use to track down problems with P/Invoke:

            $ MONO_LOG_LEVEL="debug" MONO_LOG_MASK="dll" mono glue.exe


       If  you  are  using  LLDB,  you  can  use  the script to print some internal data
       structures with it.   To use this, add this to your $HOME/.lldbinit file:
       command script import $PREFIX/lib/mono/lldb/

       Where $PREFIX is the prefix value that you used when you configured Mono (typically /usr).

       Once this is done, then you can inspect some Mono Runtime data structures, for example:
       (lldb) p method

       (MonoMethod *) $0 = 0x05026ac0 [mscorlib]System.OutOfMemoryException:.ctor()


       Mono's XML serialization engine  by  default  will  use  a  reflection-based  approach  to
       serialize  which  might be slow for continuous processing (web service applications).  The
       serialization engine will determine when a class must use a hand-tuned serializer based on
       a  few  parameters and if needed it will produce a customized C# serializer for your types
       at  runtime.   This  customized  serializer  then  gets  dynamically  loaded   into   your

       You can control this with the MONO_XMLSERIALIZER_THS environment variable.

       The  possible  values  are  `no'  to  disable the use of a C# customized serializer, or an
       integer that is the minimum number of uses  before  the  runtime  will  produce  a  custom
       serializer  (0  will  produce  a  custom serializer on the first access, 50 will produce a
       serializer on the 50th use). Mono will  fallback  to  an  interpreted  serializer  if  the
       serializer  generation  somehow fails. This behavior can be disabled by setting the option
       `nofallback' (for example: MONO_XMLSERIALIZER_THS=0,nofallback).


              Turns off the garbage collection in Mono.  This should be only used  for  debugging

              (Also  http_proxy)  If  set,  web  requests  using  the  Mono Class Library will be
              automatically proxied through the given URL.  Not supported on Windows, Mac OS, iOS
              or Android. See also NO_PROXY.

              When  Mono  is compiled with LLVM support, this instructs the runtime to stop using
              LLVM after the specified number of methods are JITed.   This  is  a  tool  used  in
              diagnostics  to help isolate problems in the code generation backend.   For example
              LLVM_COUNT=10 would only compile 10 methods with LLVM and then switch to  the  Mono
              JIT engine.  LLVM_COUNT=0 would disable the LLVM engine altogether.

              If set, this variable will instruct Mono to ahead-of-time compile new assemblies on
              demand and store the result into a cache in ~/.mono/aot-cache.

              Mono contains a feature which  allows  modifying  settings  in  the  .config  files
              shipped  with  Mono  by  using  config section mappers. The mappers and the mapping
              rules are defined in the $prefix/etc/mono/2.0/ file and, optionally, in
              the file found in the top-level directory of your ASP.NET application.
              Both files are read by System.Web on application startup, if they are found at  the
              above  locations.  If  you  don't want the mapping to be performed you can set this
              variable in your environment before starting the application and no action will  be

              Mono  has  a cache of ConfigSection objects for speeding up WebConfigurationManager
              queries. Its default size is 100 items, and  when  more  items  are  needed,  cache
              evictions  start  happening.  If  evictions  are  too  frequent  this  could impose
              unnecessary overhead, which could be avoided by using this environment variable  to
              set up a higher cache size (or to lower memory requirements by decreasing it).

              If  set,  causes  Mono.Cairo to collect stack traces when objects are allocated, so
              that the finalization/Dispose warnings include  information  about  the  instance's

              If  set,  this  variable  overrides  the  default  system  configuration  directory
              ($PREFIX/etc). It's used to locate machine.config file.

              Sets the style of COM interop.  If the value of this variable is "MS" Mono will use
              string  marhsalling  routines  from  the liboleaut32 for the BSTR type library, any
              other values will use the mono-builtin BSTR string marshalling.

              If  set,  this  variable  overrides  the   default   runtime   configuration   file
              ($PREFIX/etc/mono/config).   The   --config  command  line  options  overrides  the
              environment variable.

              Override the automatic cpu detection mechanism. Currently used only  on  arm.   The
              format of the value is as follows:

                   "armvV [thumb[2]]"

              where  V  is the architecture number 4, 5, 6, 7 and the options can be currently be
              "thumb" or "thumb2". Example:

                   MONO_CPU_ARCH="armv4 thumb" mono ...

              When Mono is built with a soft float fallback on ARM and this variable  is  set  to
              "1", Mono will always emit soft float code, even if a VFP unit is detected.

              This   is   a   debugging  aid  used  to  force  limits  on  the  FileSystemWatcher
              implementation in Darwin.   There is no limit by default.

              If set, tells mono NOT to attempt using native asynchronous I/O services.  In  that
              case,  a  default  select/poll  implementation  is  used. Currently only epoll() is

              If this environment variable is `yes', the runtime uses unmanaged collation  (which
              actually  means  no  culture-sensitive  collation).  It internally disables managed
              collation functionality invoked via the members of System.Globalization.CompareInfo
              class. Collation is enabled by default.

              Unix only: If set, disables the shared memory files used for cross-process handles:
              process have only private handles.  This means that process and thread handles  are
              not  available  to  other  processes,  and  named  mutexes,  named events and named
              semaphores are not visible between processes.  This  is  can  also  be  enabled  by
              default by passing the "--disable-shared-handles" option to configure.  This is the
              default from mono 2.8 onwards.

              Unix only: If  set,  disable  usage  of  shared  memory  for  exposing  performance
              counters.  This  means  it will not be possible to both externally read performance
              counters from this processes or read those of external processes.

              When set, enables the use of a fully managed DNS resolver instead  of  the  regular
              libc functions. This resolver performs much better when multiple queries are run in

              Note that /etc/nsswitch.conf will be ignored.

              For platforms that do not otherwise have a way of obtaining random bytes  this  can
              be  set  to  the  name  of  a file system socket on which an egd or prngd daemon is

              This makes the Mono runtime and the SGen garbage collector run in cooperative  mode
              as  opposed  to run on preemptive mode.   Preemptive mode is the mode that Mono has
              used historically, going back to the Boehm days, where the garbage collector  would
              run  at  any  point  and  suspend execution of all threads as required to perform a
              garbage  collection.   The  cooperative  mode  on  the  other  hand  requires   the
              cooperation  of  all threads to stop at a safe point.   This makes for an easier to
              debug garbage collector.   As of Mono 4.3.0 it is a work in progress, and while  it
              works,  it  has  not  been  used extensively.   This option enabled the feature and
              allows us to find spots  that  need  to  be  tuned  for  this  mode  of  operation.
              Alternatively,  this  mode  can  be  enabled  at  compile time by using the --with-
              cooperative-gc flag when calling configure.

              This environment variable allows you to pass  command  line  arguments  to  a  Mono
              process  through the environment.   This is useful for example to force all of your
              Mono processes to use LLVM or SGEN without having to modify any launch scripts.

              Used to pass extra options to the debugger agent  in  the  runtime,  as  they  were
              passed using --debugger-agent=.

              Sets  the  type  of  event  log  provider to use (for System.Diagnostics.EventLog).
              Possible values are:

                     Persists event logs and entries to the local file system.  The directory  in
                     which  to persist the event logs, event sources and entries can be specified
                     as part of the value.  If the path is not explicitly  set,  it  defaults  to
                     "/var/lib/mono/eventlog" on unix and "%APPDATA%no\ventlog" on Windows.

              win32  Uses the native win32 API to write events and registers event logs and event
                     sources in the registry.   This is only available on Windows.  On Unix,  the
                     directory  permission  for individual event log and event source directories
                     is set to 777 (with +t bit) allowing everyone to read and  write  event  log
                     entries  while  only  allowing  entries  to  be  deleted by the user(s) that
                     created them.

              null   Silently discards any events.

              The default is "null" on Unix (and versions of Windows before NT), and  "win32"  on
              Windows NT (and higher).

              If  set,  contains  a  colon-separated  list  of text encodings to try when turning
              externally-generated text (e.g. command-line arguments or filenames) into  Unicode.
              The  encoding  names  come  from  the  list provided by iconv, and the special case
              "default_locale" which refers to the current locale's default encoding.

              When reading externally-generated text strings UTF-8 is tried first, and then  this
              list  is  tried  in  order  with the first successful conversion ending the search.
              When writing external text (e.g. new filenames or arguments to new  processes)  the
              first item in this list is used, or UTF-8 if the environment variable is not set.

              The  problem  with  using  MONO_EXTERNAL_ENCODINGS to process your files is that it
              results in a problem: although its possible to get the right file name  it  is  not
              necessarily  possible  to  open  the  file.   In  general if you have problems with
              encodings in your filenames you should use the "convmv" program.

              When using Mono with the SGen garbage  collector  this  variable  controls  several
              parameters  of  the  collector.   The variable's value is a comma separated list of

                     Sets the maximum size of the heap. The size is specified in bytes  and  must
                     be  a  power  of  two.  The suffixes `k', `m' and `g' can be used to specify
                     kilo-, mega- and gigabytes, respectively.  The  limit  is  the  sum  of  the
                     nursery,  major  heap  and  large object heap. Once the limit is reached the
                     application will receive OutOfMemoryExceptions when trying to allocate.  Not
                     the full extent of memory set in max-heap-size could be available to satisfy
                     a single allocation due to internal fragmentation. By default heap limits is
                     disabled and the GC will try to use all available memory.

                     Sets  the size of the nursery.  The size is specified in bytes and must be a
                     power of two.  The suffixes `k', `m' and `g' can be used to  specify  kilo-,
                     mega-  and gigabytes, respectively.  The nursery is the first generation (of
                     two).  A larger nursery will usually speed up the program but will obviously
                     use more memory.  The default nursery size 4 MB.

              major=collector Specifies which major collector to use.
                     Options  are  `marksweep' for the Mark&Sweep collector, and `marksweep-conc'
                     for concurrent Mark&Sweep.  The non-concurrent Mark&Sweep collector  is  the

                     Once the heap size gets larger than this size, ignore what the default major
                     collection trigger metric says and only allow four nursery size's  of  major
                     heap growth between major collections.

                     Sets  the evacuation threshold in percent.  This option is only available on
                     the Mark&Sweep major collectors.  The value must be an integer in the  range
                     0  to  100.   The default is 66.  If the sweep phase of the collection finds
                     that the occupancy  of  a  specific  heap  block  type  is  less  than  this
                     percentage,  it will do a copying collection for that block type in the next
                     major collection, thereby restoring occupancy to close to  100  percent.   A
                     value of 0 turns evacuation off.

                     Enables  or  disables  lazy sweep for the Mark&Sweep collector.  If enabled,
                     the sweeping of individual major heap blocks is done piecemeal whenever  the
                     need arises, typically during nursery collections.  Lazy sweeping is enabled
                     by default.

                     Enables or disables concurrent  sweep  for  the  Mark&Sweep  collector.   If
                     enabled,  the  iteration  of all major blocks to determine which ones can be
                     freed and which ones have to be kept and swept, is  done  concurrently  with
                     the running program.  Concurrent sweeping is enabled by default.

                     Specifies  how  application threads should be scanned. Options are `precise`
                     and `conservative`. Precise marking allow the collector to know what  values
                     on  stack are references and what are not.  Conservative marking threats all
                     values as potentially references and leave them untouched.  Precise  marking
                     reduces  floating garbage and can speed up nursery collection and allocation
                     rate, it has the downside  of  requiring  a  significant  extra  memory  per
                     compiled method. The right option, unfortunately, requires experimentation.

                     Specifies  the target save ratio for the major collector. The collector lets
                     a given amount of memory to be  promoted  from  the  nursery  due  to  minor
                     collections  before  it triggers a major collection. This amount is based on
                     how much memory it expects to free. It is represented as a ratio of the size
                     of the heap after a major collection.  Valid values are between 0.1 and 2.0.
                     The default is 0.5.  Smaller values will keep the major  heap  size  smaller
                     but  will  trigger  more major collections. Likewise, bigger values will use
                     more memory and result in less frequent major collections.  This  option  is
                     EXPERIMENTAL, so it might disappear in later versions of mono.

                     Specifies  the  default allocation allowance when the calculated size is too
                     small. The allocation allowance is how much  memory  the  collector  let  be
                     promoted  before triggered a major collection.  It is a ratio of the nursery
                     size.  Valid values are between 1.0 and 10.0. The default is  4.0.   Smaller
                     values lead to smaller heaps and more frequent major collections.  Likewise,
                     bigger values will allow the heap to grow faster but use more memory when it
                     reaches  a  stable size.  This option is EXPERIMENTAL, so it might disappear
                     in later versions of mono.

                     Specifies which minor collector to use. Options are 'simple' which  promotes
                     all  objects  from  the  nursery  directly to the old generation and 'split'
                     which lets object stay longer on the nursery before promoting.

                     Specifies the ratio of memory from the nursery to be use by the alloc space.
                     This only can only be used with the split minor collector.  Valid values are
                     integers between 1 and 100. Default is 60.

                     Specifies the required age of an object must reach inside the nursery before
                     been  promoted  to  the  old generation. This only can only be used with the
                     split minor collector.  Valid values are integers between 1 and 14.  Default
                     is 2.

                     Enables  or  disables  cementing.   This  can  dramatically  shorten nursery
                     collection times on some benchmarks where pinned  objects  are  referred  to
                     from the major heap.

                     This   forbids   the  major  collector  from  performing  synchronous  major
                     collections.  The major collector might want to do a synchronous  collection
                     due  to  excessive  fragmentation.  Disabling this might trigger OutOfMemory
                     error in situations that would otherwise not happen.

              When using Mono with the SGen garbage collector this environment  variable  can  be
              used  to  turn  on  various debugging features of the collector.  The value of this
              variable is a comma  separated  list  of  words.   Do  not  use  these  options  in

              number Sets the debug level to the specified number.

                     After  each  major collection prints memory consumption for before and after
                     the collection and the allowance for the minor collector, i.e. how much  the
                     heap  is  allowed  to  grow  from  minor  collections  before the next major
                     collection is triggered.

                     Gathers statistics on the classes whose objects are pinned  in  the  nursery
                     and for which global remset entries are added.  Prints those statistics when
                     shutting down.


                     This performs a consistency check on minor collections and also  clears  the
                     nursery  at  collection  time,  instead  of  the  default,  when buffers are
                     allocated (clear-at-gc).   The consistency check ensures that there  are  no
                     major to minor references that are not on the remembered sets.

                     Checks  that  the  mod-union  cardtable  is consistent before each finishing
                     major collection pause.  This check is only applicable to  concurrent  major

                     Checks  that  mark  bits in the major heap are consistent at the end of each
                     major collection.  Consistent mark bits mean that if an  object  is  marked,
                     all objects that it had references to must also be marked.

                     After nursery collections, and before starting concurrent collections, check
                     whether all nursery objects  are  pinned,  or  not  pinned  -  depending  on
                     context.  Does nothing when the split nursery collector is used.

                     Performs  a  check  to  make sure that no references are left to an unloaded

                     Clears the nursery incrementally when the thread  local  allocation  buffers
                     (TLAB)  are  created.   The  default  setting clears the whole nursery at GC

                     Clears the nursery incrementally when the thread  local  allocation  buffers
                     (TLAB)  are  created,  but  at  GC time fills it with the byte `0xff`, which
                     should result in a crash more quickly  if  `clear-at-tlab-creation`  doesn't
                     work properly.

                     This clears the nursery at GC time instead of doing it when the thread local
                     allocation buffer (TLAB) is created.  The default is to clear the nursery at
                     TLAB creation time.

                     Don't  do  minor collections.  If the nursery is full, a major collection is
                     triggered instead, unless it, too, is disabled.

                     Don't do major collections.

                     Forces the GC to scan the stack conservatively, even if precise scanning  is

                     Disables the managed allocator.

                     If  set,  does a plausibility check on the scan_starts before and after each

                     If set, does a complete object walk of the nursery  at  the  start  of  each
                     minor collection.

                     If  set,  dumps  the  contents  of  the  nursery  at the start of each minor
                     collection. Requires verify-nursery-at-minor-gc to be set.

                     Dumps  the  heap  contents  to  the  specified  file.    To  visualize   the
                     information, use the mono-heapviz tool.

                     Outputs the debugging output to the specified file.   For this to work, Mono
                     needs to be compiled with the BINARY_PROTOCOL define on sgen-gc.c.   You can
                     then use this command to explore the output
                                     sgen-grep-binprot 0x1234 0x5678 < file

                     If  set, objects allocated in the nursery are suffixed with a canary (guard)
                     word, which is checked on each minor collection. Can be used to detect/debug
                     heap corruption issues.

                     If enabled, finalizers will not be run.  Everything else will be unaffected:
                     finalizable objects will still be put into the finalization queue where they
                     survive  until they're scheduled to finalize.  Once they're not in the queue
                     anymore they will be collected regularly.   If  a  list  of  comma-separated
                     class names is given, only objects from those classes will not be finalized.

                     Log verbosely around the finalization process to aid debugging.

              Provides a prefix the runtime uses to look for Global Assembly Caches.  Directories
              are separated by the platform path  separator  (colons  on  unix).  MONO_GAC_PREFIX
              should  point  to  the  top  directory  of  a prefixed install. Or to the directory
              provided      in      the       gacutil       /gacdir       command.       Example:

              Enables  some  filename rewriting support to assist badly-written applications that
              hard-code Windows paths.  Set to a colon-separated list of "drive" to  strip  drive
              letters,  or  "case"  to  do case-insensitive file matching in every directory in a
              path.  "all" enables all rewriting methods.   (Backslashes  are  always  mapped  to
              slashes if this variable is set to a valid option).
              For example, this would work from the shell:

                   export MONO_IOMAP

              If  you are using mod_mono to host your web applications, you can use the MonoIOMAP
              directive instead, like this:

                   MonoIOMAP <appalias> all

              See mod_mono(8) for more details.

              Additionally. Mono includes a profiler  module  which  allows  one  to  track  what
              adjustements  to  file  paths IOMAP code needs to do. The tracking code reports the
              managed location (full stack trace) from which the IOMAP-ed call was made  and,  on
              process  exit, the locations where all the IOMAP-ed strings were created in managed
              code. The latter report is only  approximate  as  it  is  not  always  possible  to
              estimate  the  actual  location  where the string was created. The code uses simple
              heuristics - it analyzes stack trace leading back to the string allocation location
              and ignores all the managed code which lives in assemblies installed in GAC as well
              as in the class libraries shipped with Mono (since they are assumed to be  free  of
              case-sensitivity  issues).  It then reports the first location in the user's code -
              in most cases this will be the place where the string is allocated or very close to
              the  location.  The  reporting code is implemented as a custom profiler module (see
              the "PROFILING" section) and can be loaded in the following way:

                   mono --profile=iomap yourapplication.exe

              Note, however, that Mono currently supports only one profiler module at a time.

              When Mono is using the LLVM code generation backend you can  use  this  environment
              variable to pass code generation options to the LLVM compiler.

              If   set  to  "disabled",  System.IO.FileSystemWatcher  will  use  a  file  watcher
              implementation which silently ignores all the watching requests.   If  set  to  any
              other   value,   System.IO.FileSystemWatcher   will   use   the   default   managed
              implementation (slow). If unset, mono will try to use inotify, FAM,  Gamin,  kevent
              under  Unix  systems  and  native API calls on Windows, falling back to the managed
              implementation on error.

              Mono supports a plugin model for its implementation of System.Messaging  making  it
              possible  to  support a variety of messaging implementations (e.g. AMQP, ActiveMQ).
              To specify which messaging implementation is to be used  the  evironement  variable
              needs  to be set to the full class name for the provider.  E.g. to use the RabbitMQ
              based AMQP implementation the variable should be set to:


              If set causes the mono process to be bound to a single processor. This may be
              useful when debugging or working around race conditions.

              Disable inlining of thread local accesses. Try setting this if you get a segfault
              early on in the execution of mono.

              Provides a search path to the runtime where to look for library
              files.   This is a tool convenient for debugging applications, but
              should not be used by deployed applications as it breaks the assembly
              loader in subtle ways.
              Directories are separated by the platform path separator (colons on unix). Example:
              Relative paths are resolved based on the launch-time current directory.
              Alternative solutions to MONO_PATH include: installing libraries into
              the Global Assembly Cache (see gacutil(1)) or having the dependent
              libraries side-by-side with the main executable.
              For a complete description of recommended practices for application
              deployment, see

              If set its the directory where the ".wapi" handle state is stored.
              This is the directory where the Windows I/O Emulation layer stores its
              shared state data (files, events, mutexes, pipes).  By default Mono
              will store the ".wapi" directory in the users's home directory.

              Uses the string value of this variable as a replacement for the host name when
              creating file names in the ".wapi" directory. This helps if the host name of
              your machine is likely to be changed when a mono application is running or if
              you have a .wapi directory shared among several different computers.
              Mono typically uses the hostname to create the files that are used to
              share state across multiple Mono processes.  This is done to support
              home directories that might be shared over the network.

              If set, extra checks are made during IO operations.  Currently, this
              includes only advisory locks around file writes.

              The name of the theme to be used by Windows.Forms.   Available themes today
              include "clearlooks", "nice" and "win32".
              The default is "win32".

              The time, in seconds, that the SSL/TLS session cache will keep it's entry to
              avoid a new negotiation between the client and a server. Negotiation are very
              CPU intensive so an application-specific custom value may prove useful for
              small embedded systems.
              The default is 180 seconds.

              The minimum number of threads in the general threadpool will be
              MONO_THREADS_PER_CPU * number of CPUs. The default value for this
              variable is 1.

              Controls the threshold for the XmlSerializer to produce a custom
              serializer for a given class instead of using the Reflection-based
              interpreter.  The possible values are `no' to disable the use of a
              custom serializer or a number to indicate when the XmlSerializer
              should start serializing.   The default value is 50, which means that
              the a custom serializer will be produced on the 50th use.

              Sets the revocation mode used when validating a X509 certificate chain (https,
              ftps, smtps...).  The default is 'nocheck', which performs no revocation check
              at all. The other possible values are 'offline', which performs CRL check (not
              implemented yet) and 'online' which uses OCSP and CRL to verify the revocation
              status (not implemented yet).

              (Also no_proxy) If both HTTP_PROXY and NO_PROXY are
              set, NO_PROXY will be treated as a comma-separated list of "bypass" domains
              which will not be sent through the proxy. Domains in NO_PROXY may contain
              wildcards, as in "*" or "build????.local". Not supported on
              Windows, Mac OS, iOS or Android.


              If set to any value, temporary source files generated by  ASP.NET  support  classes
              will not be removed. They will be kept in the user's temporary directory.

              If  set,  enables some features of the runtime useful for debugging.  This variable
              should contain a  comma  separated  list  of  debugging  options.   Currently,  the
              following options are supported:

                     Enables small structs alignment to 4/8 bytes.

                     When  this  option is set on ARM, a fallback TLS will be used instead of the
                     default fast TLS.

                     If this variable is set, when the Mono VM runs into a verification  problem,
                     instead  of  throwing an exception it will break into the debugger.  This is
                     useful when debugging verifier problems

              casts  This option can be used to get more detailed  information  from  InvalidCast
                     exceptions, it will provide information about the types involved.

                     This  option  causes  the runtime to check for calling convention mismatches
                     when using pinvoke, i.e. mixing cdecl/stdcall. It only works on windows.  If
                     a mismatch is detected, an ExecutionEngineException is thrown.

                     Collects  information  about  pagefaults.   This is used internally to track
                     the number of page faults  produced  to  load  metadata.   To  display  this
                     information you must use this option with "--stats" command line option.

                     When  this option is set, the runtime will invalidate the domain memory pool
                     instead of destroying it.

                     Disables a compiler optimization where the frame pointer is omitted from the
                     stack. This optimization can interact badly with debuggers.

                     This  is  an  Optimization  for  multi-AppDomain applications (most commonly
                     ASP.NET applications).  Due to internal limitations Mono,  Mono  by  default
                     does not use typed allocations on multi-appDomain applications as they could
                     leak memory when a domain is unloaded.  Although this is a fine default, for
                     applications  that  use more than on AppDomain heavily (for example, ASP.NET
                     applications) it is worth trading off the  small  leaks  for  the  increased
                     performance  (additionally,  since ASP.NET applications are not likely going
                     to unload the application domains on production systems, it is  worth  using
                     this feature).

                     Instructs the runtime to try to use a generic runtime-invoke wrapper instead
                     of creating one invoke wrapper.

                     Makes the JIT generate an  explicit  NULL  check  on  variable  dereferences
                     instead  of  depending on the operating system to raise a SIGSEGV or another
                     form of trap event when an invalid memory location is accessed.

              gdb    Equivalent to setting the MONO_XDEBUG variable, this emits  symbols  into  a
                     shared  library  as the code is JITed that can be loaded into GDB to inspect

                     Automatically generates sequence points where the IL stack is empty.   These
                     are places where the debugger can set a breakpoint.

                     Unless  the  option is used, the runtime generates sequence points data that
                     maps native offsets to IL offsets. Sequence point data is used to display IL
                     offset in stacktraces. Stacktraces with IL offsets can be symbolicated using
                     mono-symbolicate tool.

                     Captures the interrupt signal (Control-C) and displays a  stack  trace  when
                     pressed.   Useful  to  find  out  where  the program is executing at a given
                     point.  This only displays the stack trace of a single thread.

                     Instructs the runtime to initialize the stack with some known  values  (0x2a
                     on x86-64) at the start of a method to assist in debuggin the JIT engine.

                     This  option will leak delegate trampolines that are no longer referenced as
                     to  present  the  user  with  more  information  about  a  delegate  misuse.
                     Basically  a  delegate  instance might be created, passed to unmanaged code,
                     and no references kept in managed code, which will garbage collect the code.
                     With this option it is possible to track down the source of the problems.

                     This  option  will  disable the GDB backtrace emitted by the runtime after a
                     SIGSEGV or SIGABRT in unmanaged code.

                     When this option is set,  the  runtime  can  share  generated  code  between
                     generic types effectively reducing the amount of code generated.

                     This  option will cause mono to abort with a descriptive message when during
                     stack unwinding after an exception it reaches a  native  stack  frame.  This
                     happens  when  a  managed delegate is passed to native code, and the managed
                     delegate throws an exception. Mono will normally try to unwind the stack  to
                     the  first  (managed)  exception  handler, and it will skip any native stack
                     frames in the process. This leads to undefined behaviour (since mono doesn't
                     know how to process native frames), leaks, and possibly crashes too.

                     This   guarantees   that  each  time  managed  code  is  compiled  the  same
                     instructions and registers are used, regardless of the size of used values.

                     This option allows using single-steps and breakpoints in hardware  where  we
                     cannot do it with signals.

                     This  option  will  suspend  the  program when a native SIGSEGV is received.
                     This is useful for debugging crashes which do not happen under gdb, since  a
                     live process contains more information than a core file.

                     This option will suspend the program when an exception occurs.

                     This option will suspend the program when an unhandled exception occurs.

              The  logging  level, possible values are `error', `critical', `warning', `message',
              `info' and `debug'.  See the DEBUGGING section for more details.

              Controls the domain of the Mono runtime that logging will apply to.   If  set,  the
              log  mask is changed to the set value. Possible values are "asm" (assembly loader),
              "type", "dll" (native library loader), "gc" (garbage collector), "cfg" (config file
              loader),  "aot"  (precompiler),  "security"  (e.g.  Moonlight  CoreCLR support) and
              "all".  The default value is "all". Changing the mask value allows you  to  display
              only  messages  for  a  certain  component.  You  can  use  multiple masks by comma
              separating them. For example to  see  config  file  messages  and  assembly  loader
              messages set you mask to "asm,cfg".

              Used  for  runtime tracing of method calls. The format of the comma separated trace
              options is:

                   [-]M:method name
                   [-]T:class name
                   disabled       Trace output off upon start.

              You can toggle trace output on/off sending a SIGUSR2 signal to the program.

              If set, enables the System.Diagnostics.DefaultTraceListener, which will  print  the
              output  of  the  System.Diagnostics  Trace  and  Debug classes.  It can be set to a
              filename, and to Console.Out or Console.Error to display output to standard  output
              or  standard  error,  respectively. If it's set to Console.Out or Console.Error you
              can append an optional prefix that will be used when writing  messages  like  this:
              Console.Error:MyProgramName.    See   the   System.Diagnostics.DefaultTraceListener
              documentation for more information.

              This eases WCF diagnostics functionality by simply outputs all  log  messages  from
              WCF  engine  to "stdout", "stderr" or any file passed to this environment variable.
              The log format is the same as usual diagnostic output.

              This throws an exception when a X11 error is encountered; by default a  message  is
              displayed but execution continues

              Set  this  value  to  1 to prevent the serializer from removing the temporary files
              that are created for fast serialization;  This might be useful when debugging.

              This is used in the System.Windows.Forms implementation when running with  the  X11
              backend.   This  is used to debug problems in Windows.Forms as it forces all of the
              commands send to X11 server  to  be  done  synchronously.    The  default  mode  of
              operation  is  asynchronous  which  makes  it  hard  to isolate the root of certain

              When the the MONO_XDEBUG env var is set, debugging info for JITted code is  emitted
              into a shared library, loadable into gdb. This enables, for example, to see managed
              frame names on gdb backtraces.

              Enables the maximum JIT verbosity for the specified method. This is  very  helpfull
              to diagnose a miscompilation problems of a specific method.

              Enables  sending  of the JITs intermediate representation for a specified method to
              the IdealGraphVisualizer tool.

              If set, makes the JIT output information about detected CPU features (such as  SSE,
              CMOV, FCMOV, etc) to stdout.

              If  set,  the  JIT  will not perform any hardware capability detection. This may be
              useful to pinpoint the cause of JIT issues. This is the default when Mono is  built
              as an AOT cross compiler, so that the generated code will run on most hardware.


       If  you  want  to use Valgrind, you will find the file `mono.supp' useful, it contains the
       suppressions for the GC which trigger incorrect warnings.  Use it like this:
           valgrind --suppressions=mono.supp mono ...


       On some platforms, Mono can expose a  set  of  DTrace  probes  (also  known  as  user-land
       statically defined, USDT Probes).

       They are defined in the file `mono.d'.

       ves-init-begin, ves-init-end
              Begin and end of runtime initialization.

       method-compile-begin, method-compile-end
              Begin  and  end  of method compilation.  The probe arguments are class name, method
              name and signature, and  in  case  of  method-compile-end  success  or  failure  of

       gc-begin, gc-end
              Begin and end of Garbage Collection.

       To verify the availability of the probes, run:
                  dtrace -P mono'$target' -l -c mono


       Mono's  Ping implementation for detecting network reachability can create the ICMP packets
       itself without requiring the system ping command to do the work.  If you  want  to  enable
       this on Linux for non-root users, you need to give the Mono binary special permissions.

       As root, run this command:
          # setcap cap_net_raw=+ep /usr/bin/mono


       On Unix assemblies are loaded from the installation lib directory.  If you set `prefix' to
       /usr, the assemblies will be located in /usr/lib.  On Windows, the assemblies  are  loaded
       from the directory where mono and mint live.

              The  directory  for  the  ahead-of-time  compiler  demand  creation  assemblies are

       /etc/mono/config, ~/.mono/config
              Mono runtime configuration file.  See  the  mono-config(5)  manual  page  for  more

       ~/.config/.mono/certs, /usr/share/.mono/certs
              Contains  Mono  certificate  stores  for users / machine. See the certmgr(1) manual
              page for more information on managing certificate stores and the  mozroots(1)  page
              for  information  on  how  to  import  the  Mozilla root certificates into the Mono
              certificate store.

              Files in this directory allow a user to customize the  configuration  for  a  given
              system assembly, the format is the one described in the mono-config(5) page.

       ~/.config/.mono/keypairs, /usr/share/.mono/keypairs
              Contains  Mono  cryptographic keypairs for users / machine. They can be accessed by
              using    a    CspParameters    object     with     DSACryptoServiceProvider     and
              RSACryptoServiceProvider classes.

       ~/.config/.isolatedstorage, ~/.local/share/.isolatedstorage, /usr/share/.isolatedstorage
              Contains  Mono  isolated  storage  for  non-roaming  users, roaming users and local
              machine.  Isolated  storage  can  be  accessed   using   the   classes   from   the
              System.IO.IsolatedStorage namespace.

              Configuration  information  for individual assemblies is loaded by the runtime from
              side-by-side   files   with   the   .config   files,   see   the   http://www.mono-
     for more information.

       Web.config, web.config
              ASP.NET  applications are configured through these files, the configuration is done
              on  a  per-directory  basis.   For  more  information  on  this  subject  see   the


       Mailing lists are listed at the



       certmgr(1),   csharp(1),   mcs(1),   mdb(1),   monocov(1),   monodis(1),   mono-config(5),
       mozroots(1), mprof-report(1), pdb2mdb(1), xsp(1), mod_mono(8).

       For more information on AOT:

       For ASP.NET-related documentation, see the xsp(1) manual page

                                                                                   Mono(Mono 3.0)