mono(1)
NAME
mono - Mono's ECMA-CLI native code generator (Just-in-Time and Ahead- of-Time)
SYNOPSIS
mono [options] file [arguments...] mono-sgen [options] file [arguments...]
DESCRIPTION
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.
PORTABILITY
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.
RUNTIME OPTIONS
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:
autoreg
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
asmonly
Instructs the AOT compiler to output assembly code
instead of an object file.
bind-to-runtime-version
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.
data-outfile=FILE.dll.aotdata
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.
direct-pinvoke
When this option is specified, P/Invoke methods are
invoked directly instead of going through the operating
system symbol lookup operation.
llvm-path=<PREFIX>
Same for the llvm tools 'opt' and 'llc'.
msym-dir=<PATH>
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.
mtriple=<TRIPLE>
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.
nimt-trampolines=[number]
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.
nodebug
Instructs the AOT compiler to not output any debugging
information.
no-direct-calls
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 calls.
dwarfdebug
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.
nrgctx-trampolines=[number]
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.
ntrampolines=[number]
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.
outfile=[filename]
Instructs the AOT compiler to save the output to the
specified file.
print-skipped-methods
If the AOT compiler cannot compile a method for any
reason, enabling this flag will output the skipped
methods to the console.
readonly-value=namespace.typename.fieldname=type/value
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).
save-temps,keep-temps
Instructs the AOT compiler to keep temporary files.
soft-debug
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.
threads=[number]
This is an experimental option for the AOT compiler to
use multiple threads when compiling the methods.
tool-prefix=<PREFIX>
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
write-symbols
Instructs the AOT compiler to emit debug symbol
information.
For more information about AOT, see: http://www.mono-
project.com/docs/advanced/aot/
--attach=[options]
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.
--debugger-agent=[options]
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:
address=host:port
Use this option to specify the IP address where your
debugger client is listening to.
loglevel=LEVEL
Specifies the diagnostics log level for
logfile=filename
Used to specify the file where the log will be stored, it
defaults to standard output.
server=[y/n]
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.
setpgid=[y/n]
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.
suspend=[y/n]
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 connection..
transport=transport_name
This is used to specify the transport that the debugger
will use to communicate. It must be specified and
currently requires this to be 'dt_socket'.
--desktop
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.
--full-aot
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-
project.com/docs/advanced/mono-llvm/
--nollvm
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:
-O=all,-deadce,-inline
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
float32
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
--runtime=VERSION
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" parameter.
The following modes are supported:
core-clr
Enables the core-clr security system, typically used for
Moonlight/Silverlight applications. It provides a much
simpler security system than CAS, see http://www.mono-
project.com/docs/web/moonlight/ for more details and
links to the descriptions of this new system.
validil
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 Mono.
verifiable
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.
--server
Configures the virtual machine to be better suited for server
operations (currently, allows a heavier threadpool
initialization).
--verify-all
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).
DEVELOPMENT OPTIONS
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 time.
mdb-optimizations
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.
--profile[=profiler[:profiler_args]]
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.
--trace[=expression]
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 notation:
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
--no-x86-stack-align
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.
--jitmap
Generate a JIT method map in a /tmp/perf-PID.map file. This file
is then used, for example, by the perf tool included in recent
Linux kernels. Each line in the file has:
HEXADDR HEXSIZE methodname
Currently this option is only supported on Linux.
JIT MAINTAINER OPTIONS
The maintainer options are only used by those developing the runtime
itself, and not typically of interest to runtime users or developers.
--bisect=optimization:filename
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 not.
--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
"System.Collections.Generic.Queue`1:Peek"
--breakonex
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 (namespace.name:methodname), this is used
for testing the compiler performance or to examine the output of
the code generator.
--compileall
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 (namespace.name:methodname). This
requires `dot' and ghostview to be installed (it expects
Ghostview to be called "gv"). The following graphs are
available:
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.
--ncompile
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.
--stats
Displays information about the work done by the runtime during
the execution of an application.
--wapi=hps|semdel
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.).
ATTACH SUPPORT
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 invocation. This support allows for example debugging applications by having the csharp shell attach to running processes.
PROFILING
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:
--profile[=profiler[:profiler_args]]
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 profiling.
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).
LOG PROFILER
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) page.
CUSTOM PROFILERS
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 `mono-profiler-custom.so'. This profiler module must be
on your dynamic linker library path.
A list of other third party profilers is available from Mono's web site
(www.mono-project.com/docs/advanced/performance-tips/)
Custom profiles are written as shared libraries. The shared library
must be called `mono-profiler-NAME.so' 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.
CODE COVERAGE
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-suite.exe
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.
DEBUGGING AIDS
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
DEBUGGING WITH LLDB
If you are using LLDB, you can use the mono.py 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/mono.py 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()
SERIALIZATION
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 application. 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).
ENVIRONMENT VARIABLES
GC_DONT_GC
Turns off the garbage collection in Mono. This should be only
used for debugging purposes
HTTP_PROXY
(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.
LLVM_COUNT
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.
MONO_AOT_CACHE
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_ASPNET_INHIBIT_SETTINGSMAP
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
$prefix/etc/mono/2.0/settings.map file and, optionally, in the
settings.map file found in the top-level directory of your
ASP.NET application. Both files are read by System.Web on
application startup, if they are found at the above locations.
If you don't want the mapping to be performed you can set this
variable in your environment before starting the application and
no action will be taken.
MONO_ASPNET_WEBCONFIG_CACHESIZE
Mono has a cache of ConfigSection objects for speeding up
WebConfigurationManager queries. Its default size is 100 items,
and when more items are needed, cache evictions start happening.
If evictions are too frequent this could impose unnecessary
overhead, which could be avoided by using this environment
variable to set up a higher cache size (or to lower memory
requirements by decreasing it).
MONO_CAIRO_DEBUG_DISPOSE
If set, causes Mono.Cairo to collect stack traces when objects
are allocated, so that the finalization/Dispose warnings include
information about the instance's origin.
MONO_CFG_DIR
If set, this variable overrides the default system configuration
directory ($PREFIX/etc). It's used to locate machine.config
file.
MONO_COM
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.
MONO_CONFIG
If set, this variable overrides the default runtime
configuration file ($PREFIX/etc/mono/config). The --config
command line options overrides the environment variable.
MONO_CPU_ARCH
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 ...
MONO_ARM_FORCE_SOFT_FLOAT
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.
MONO_DARWIN_WATCHER_MAXFDS
This is a debugging aid used to force limits on the
FileSystemWatcher implementation in Darwin. There is no limit
by default.
MONO_DISABLE_AIO
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 supported.
MONO_DISABLE_MANAGED_COLLATION
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.
MONO_DISABLE_SHM
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.
MONO_DISABLE_SHARED_AREA
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.
MONO_DNS
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 parallel.
Note that /etc/nsswitch.conf will be ignored.
MONO_EGD_SOCKET
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 listening.
MONO_ENABLE_COOP
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.
MONO_ENV_OPTIONS
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.
MONO_ENV_OPTIONS
Used to pass extra options to the debugger agent in the runtime,
as they were passed using --debugger-agent=.
MONO_EVENTLOG_TYPE
Sets the type of event log provider to use (for
System.Diagnostics.EventLog). Possible values are:
local[:path]
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).
MONO_EXTERNAL_ENCODINGS
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.
MONO_GC_PARAMS
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 words.
max-heap-size=size
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.
nursery-size=size
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 default.
soft-heap-limit=size
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.
evacuation-threshold=threshold
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.
(no-)lazy-sweep
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.
(no-)concurrent-sweep
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.
stack-mark=mark-mode
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.
save-target-ratio=ratio
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.
default-allowance-ratio=ratio
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.
minor=minor-collector
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.
alloc-ratio=ratio
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.
promotion-age=age
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.
(no-)cementing
Enables or disables cementing. This can dramatically
shorten nursery collection times on some benchmarks where
pinned objects are referred to from the major heap.
allow-synchronous-major
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.
MONO_GC_DEBUG
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 production.
number Sets the debug level to the specified number.
print-allowance
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.
print-pinning
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.
collect-before-allocs
check-at-minor-collections
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.
mod-union-consistency-check
Checks that the mod-union cardtable is consistent before
each finishing major collection pause. This check is
only applicable to concurrent major collectors.
check-mark-bits
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.
check-nursery-pinned
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.
xdomain-checks
Performs a check to make sure that no references are left
to an unloaded AppDomain.
clear-at-tlab-creation
Clears the nursery incrementally when the thread local
allocation buffers (TLAB) are created. The default
setting clears the whole nursery at GC time.
debug-clear-at-tlab-creation
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.
clear-at-gc
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.
disable-minor
Don't do minor collections. If the nursery is full, a
major collection is triggered instead, unless it, too, is
disabled.
disable-major
Don't do major collections.
conservative-stack-mark
Forces the GC to scan the stack conservatively, even if
precise scanning is available.
no-managed-allocator
Disables the managed allocator.
check-scan-starts
If set, does a plausibility check on the scan_starts
before and after each collection
verify-nursery-at-minor-gc
If set, does a complete object walk of the nursery at the
start of each minor collection.
dump-nursery-at-minor-gc
If set, dumps the contents of the nursery at the start of
each minor collection. Requires verify-nursery-at-minor-
gc to be set.
heap-dump=file
Dumps the heap contents to the specified file. To
visualize the information, use the mono-heapviz tool.
binary-protocol=file
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
nursery-canaries
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.
do-not-finalize(=classes)
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-finalizers
Log verbosely around the finalization process to aid
debugging.
MONO_GAC_PREFIX
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:
/home/username/.mono:/usr/local/mono/
MONO_IOMAP
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:
MONO_IOMAP=drive:case
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.
MONO_LLVM
When Mono is using the LLVM code generation backend you can use
this environment variable to pass code generation options to the
LLVM compiler.
MONO_MANAGED_WATCHER
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_MESSAGING_PROVIDER
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:
Mono.Messaging.RabbitMQ.RabbitMQMessagingProvider,Mono.Messaging.RabbitMQ
MONO_NO_SMP
If set causes the mono process to be bound to a single processor. This may be
useful when debugging or working around race conditions.
MONO_NO_TLS
Disable inlining of thread local accesses. Try setting this if you get a segfault
early on in the execution of mono.
MONO_PATH
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:
/home/username/lib:/usr/local/mono/lib
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
http://www.mono-project.com/docs/getting-started/application-deployment/
MONO_SHARED_DIR
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.
MONO_SHARED_HOSTNAME
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.
MONO_STRICT_IO_EMULATION
If set, extra checks are made during IO operations. Currently, this
includes only advisory locks around file writes.
MONO_THEME
The name of the theme to be used by Windows.Forms. Available themes today
include "clearlooks", "nice" and "win32".
The default is "win32".
MONO_TLS_SESSION_CACHE_TIMEOUT
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.
MONO_THREADS_PER_CPU
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.
MONO_XMLSERIALIZER_THS
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.
MONO_X509_REVOCATION_MODE
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).
NO_PROXY
(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 "*.mono-project.com" or "build????.local". Not supported on
Windows, Mac OS, iOS or Android.
ENVIRONMENT VARIABLES FOR DEBUGGING
MONO_ASPNET_NODELETE
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.
MONO_DEBUG
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:
align-small-structs
Enables small structs alignment to 4/8 bytes.
arm-use-fallback-tls
When this option is set on ARM, a fallback TLS will be
used instead of the default fast TLS.
break-on-unverified
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.
check-pinvoke-callconv
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.
collect-pagefault-stats
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.
debug-domain-unload
When this option is set, the runtime will invalidate the
domain memory pool instead of destroying it.
disable_omit_fp
Disables a compiler optimization where the frame pointer
is omitted from the stack. This optimization can interact
badly with debuggers.
dont-free-domains
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).
dyn-runtime-invoke
Instructs the runtime to try to use a generic runtime-
invoke wrapper instead of creating one invoke wrapper.
explicit-null-checks
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 symbols.
gen-seq-points
Automatically generates sequence points where the IL
stack is empty. These are places where the debugger can
set a breakpoint.
no-compact-seq-points
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.
handle-sigint
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.
init-stacks
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.
keep-delegates
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.
no-gdb-backtrace
This option will disable the GDB backtrace emitted by the
runtime after a SIGSEGV or SIGABRT in unmanaged code.
partial-sharing
When this option is set, the runtime can share generated
code between generic types effectively reducing the
amount of code generated.
reverse-pinvoke-exceptions
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.
single-imm-size
This guarantees that each time managed code is compiled
the same instructions and registers are used, regardless
of the size of used values.
soft-breakpoints
This option allows using single-steps and breakpoints in
hardware where we cannot do it with signals.
suspend-on-sigsegv
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.
suspend-on-exception
This option will suspend the program when an exception
occurs.
suspend-on-unhandled
This option will suspend the program when an unhandled
exception occurs.
MONO_LOG_LEVEL
The logging level, possible values are `error', `critical',
`warning', `message', `info' and `debug'. See the DEBUGGING
section for more details.
MONO_LOG_MASK
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".
MONO_TRACE
Used for runtime tracing of method calls. The format of the
comma separated trace options is:
[-]M:method name
[-]N:namespace
[-]T:class name
[-]all
[-]program
disabled Trace output off upon start.
You can toggle trace output on/off sending a SIGUSR2 signal to
the program.
MONO_TRACE_LISTENER
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.
MONO_WCF_TRACE
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.
MONO_XEXCEPTIONS
This throws an exception when a X11 error is encountered; by
default a message is displayed but execution continues
MONO_XMLSERIALIZER_DEBUG
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.
MONO_XSYNC
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 problems.
MONO_XDEBUG
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.
MONO_VERBOSE_METHOD
Enables the maximum JIT verbosity for the specified method. This
is very helpfull to diagnose a miscompilation problems of a
specific method.
MONO_JIT_DUMP_METHOD
Enables sending of the JITs intermediate representation for a
specified method to the IdealGraphVisualizer tool.
MONO_VERBOSE_HWCAP
If set, makes the JIT output information about detected CPU
features (such as SSE, CMOV, FCMOV, etc) to stdout.
MONO_CONSERVATIVE_HWCAP
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.
VALGRIND
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 ...
DTRACE
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 compilation.
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
PERMISSIONS
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
FILES
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.
~/.mono/aot-cache
The directory for the ahead-of-time compiler demand creation
assemblies are located.
/etc/mono/config, ~/.mono/config
Mono runtime configuration file. See the mono-config(5) manual
page for more information.
~/.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.
~/.mono/assemblies/ASSEMBLY/ASSEMBLY.config
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.
<assembly>.config
Configuration information for individual assemblies is loaded by
the runtime from side-by-side files with the .config files, see
the http://www.mono-project.com/Config 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 http://www.mono-
project.com/Config_system.web page.
MAILING LISTS
Mailing lists are listed at the http://www.mono- project.com/community/help/mailing-lists/
WEB SITE
http://www.mono-project.com
SEE ALSO
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: http://www.mono- project.com/docs/advanced/aot/ For ASP.NET-related documentation, see the xsp(1) manual page Mono(Mono 3.0)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
