Mono 1.2 Release

What is new in Mono 1.2

A general overview of the Mono project is available in the opening presentation for the 2006 Mono Meeting. A number of presentations on various Mono-related technologies are available also from this page


The Windows.Forms 1.1 API is now available, it includes all of the controls in the standard specification, a complete System.Drawing implementation.

The Windows.Forms implementation has a WndProc compatible design, so most third party widgets that use WndProc to achieve special effects will work out of the box.

Currently there are drivers for X11 and Win32 and will run on Windows systems or systems with the X11 windowing system (Linux, Unix and OSX when using the X11 package).


System.Drawing is now complete, and in addition to being the underlying rendering engine for Windows.Forms, it has also been tested for using third party controls that heavily depend on it.


An implementation of ServiceProcess is now available, see the mono-service man page for details.


We now have a basic implementation of System.Transactions. The implementation uses a Lightweight Transaction Manager (LTM) allowing multiple volatile and/or a single durable resource manager.

C# Compiler

Mono 1.2 ships with complete C# 1.0 and C# 2.0 compilers, called mcs and gmcs respectively.

The C# compilers are built on C# themselves and they are faster than in previous versions. They are able to compile 26k lines of C# code per second.

In addition to complete the 2.0 language coverage, much effort has been placed on providing good error reports and warnings.

For more details about the compiler see our C# Compiler Page

Mono Ports

The Mono 1.2 code generator has been ported to a variety of new platforms, both 32-bit and 64 bit ports are supported and today they include the following architectures and operating systems:

32 bit systems: x86, PowerPC, ARM, s390, SPARC.

64 bit systems: x86-64, s390x, Itanium (IA64).

In addition, our operating system support has expanded and many improvements are included for OSX, Windows and BSD.

In addition preview ports for Alpha and MIPS are also available.

For more information see our detailed list of supported platforms.


These are some of the highlights of the optimizations done between Mono 1.0 and Mono 1.2, but they are only a subset.

Default Optimizations: inlining, dead code elimination, constant folding and constant propagation are now added to the default set of optimizations and have a noticeable impact on performance (anywhere from 6% to 30% depending on the architecture and particular tests).

Ahead of Time Compilation: The Mono runtime now supports ahead-of-time (AOT) compilation, startup performance is actually reduced and the code is actually shared across multiple Mono instances reducing the overall memory consumption of applications. AOT is not enabled by default on the installation of Mono 1.2 assemblies, but can be done by end users by running:

	mono --aot assembly.dll

For all the system assemblies, or assemblies in the GAC.

Arrays Bounds Check Elimination: If the JIT can infer that access to an array (for example in a loop) will not be out of range, the JIT will not emit the array range check operations (must use abcrem optimization).

Partial Redundancy Elimination: An SSA-based partial redundancy elimination has been added, and implements various partial redundancy optimizations (code hoisting, subexpression elimination and more).

Runtime: The runtime is now statically linked, and uses the __thread attribute for thread local storage, which provided a performance boost.

Garbage Collector: We now use Boehm GC in precise mode as opposed to fully conservative mode. We also use it with a precise set of GC roots which greatly improved Garbage Collection performance.

Remoting: performance for the cross application domain channel. Calls across application domains are now faster (up to 10 times in some cases). TCP and HTTP transports are now a few order of magnitude faster than in 1.0.

Crytpography: Many improvements were made in cryptographic performance, including 8% for SHA1, 5% for SHA256 and 20% for TripleDES and MACTripleDES. As well, weak key detection for DES is 16 times faster.

New padding modes ANSI X9.23 and ISO 10126 were implemented (for 2.0) for symmetric ciphers and MACTripleDES;

System.Threading.Interlocked: these are now JIT-compiled instead of being calls

VM Diet: the VM has gone through a diet, and many data structures are smaller, and most data is now shared across multiple Mono instances; Data structures are now only loaded on demand, reducing startup time, debug information is now loaded using mmap.

New work to improve Mono's performance is detailed in Mono Summit JIT presentation.


We have a completely new reimplementation of the CompareInfo infrastructure in this release of Mono, a managed implementation of string collation that is compatible with Windows collation.

A new framework for RegionInfo information.

Support for Cultures, date time formats has been greatly expanded as well.

IO Layer

Mono no longer uses a separate daemon for coordinating IO operations

The new portability laye address those problems without requiring changes to your code. This will remove a large component of the porting cycle as a whole class of obnoxious problems are gone.

The new portability framework is enabled by setting the environment variable MONO_IOMAP (which we will likely rename to something shorter) to one of the following values:

In addition, if any of those options are enabled, the directory separator mapping is also turned on. So this basically means that you have to type this, or include this in your script that launches your application:

	$ export MONO_IOMAP=all
	$ mono myapp.exe

For ASP.NET applications hosted with mod_mono, you can add the following directive to your Apache configuration file:

	MonoSetEnv MONO_IOMAP=all


Mono 1.2 now contains contains a statistical profiler, as well as a profiling interface.

Developers can create their own profilers and tools to instrument code at runtime and capture interesting code generation and memory related events.

A few of the existing profilers include: a code coverage profiling module, heap-buddy and heap-shot.

For more information about profiling see the performance tips page.

2.0 API support

The ECMA 1.0 and 2.0 API profiles have been implemented. To build applications that target the 1.0 API use the mcs compiler; To target the 2.0 API use the gmcs compiler.

ADO.NET, ASP.NET, System.Configuration, and Windows.Forms only contain partial support for 2.0 APIs, full support will only be available in Mono 2.0.

In addition memory usage has gone down all across the board, in particular in core class libraries like System.XML.

Mono.Posix improvements

Jonathan Pryor lead the development of a new namespace which rationalizes the old Mono.Posix namespace, and also adds integration classes between the Posix world and the .NET world (the old libraries merely exposed the syscall interface).

The new namespace is called Mono.Unix namespace, and it contains the new Syscall class which exports 64-bit APIs. This should now be portable across 32-bit and 64-bit platforms.

Added higher-level wrapper classes, all prefixed with Unix, to present a .NET-like API over the Syscall functionality.

The Mono.Unix namespace is also CLS compliant. The low-level Syscall and Stdlib and related types will move into the Mono.Unix.Native namespace. The UnixConvert, UnixDirectory, UnixFile, UnixGroup, and UnixUser classes are obsolete and will be removed in a future release. The types of existing members will change in the next release.

The existing Mono.Posix namespace should be considered deprecated (or at least unmaintained), in preference to the Mono.Unix namespace.

New assemblies

We now ship with bindings for the Cairo API.

Firebird provider is now bundled with Mono.

Npgsql is now bundled with Mono.

Visual Basic, JavaScript and Java

Runtimes for both Visual Basic .NET 1.0 and 2.0 are now included.

A runtime for JScript is included.

IKVM is now bundled with the Mono distribution, and allows Java applications to be executed with Mono and the IKVM Java Virtual Machine.


Bundles are a mechanism to bundle in a single binary the Mono runtime, its dependencies and your application to produce a standalone application.

We have now introduced the `mkbundle' program that will assist developers in creating self-contained applications built with Mono, and it can optionally compress all the assemblies bundled, as well as creating static binaries.


Compatibility has been greatly improved in all areas, and test suites for the compilers and class libraries have been integrated.

System.Reflection.Emit API now is able to emit debugging information in mdb format.

Support for the registry is now provided on Linux and Windows.

An EventLog implementation is available on both Unix and Windows, to use set the MONO_EVENTLOG_TYPE variable like this:

Mono now supports the #- heap (incremental builds).

File System Watching

Support for inotify on Linux and KQueue on BSD is now included to monitor file system changes through the FileSystemWatcher interface.


Commons.Xml.Relaxng is now part of the standard distribution, and has been greatly expanded, it now also contains an NVDL implementation and contains a compact syntax writer and a grammar inference engine.

System.Data and Data Providers

Sqlite provide now supports Sqlite 2 and 3 installations (runtime detection).

Updated Libraries

Updated to newer Novell.LDAP libraries and improved System.DirectoryServices

Include the new ICSharpCode.SharpZipLib.


A major rewrite to ASP.NET is now available as part of this release, the highlights of the new code include:

XSP and Mod_mono


Many new tools are part of Mono 1.2:


A copy of NUnit is now bundled with Mono.


Monodoc now defaults to use the Mozilla rendering engine to display its values, thanks to Mario Sopena and the Google Summer of Code effort and it also uses CSS to render its pages.

Monodoc will now also show pending contributions that you might have in your file system as well as including search support.


A new Mono debugger will be shortly available (alpha releases are now available for download).

Sending the QUIT signal to a running Mono process will produce a stack trace of each thread. This is a long requested feature to assist folks debugging multi-threaded applications (Zoltan).

Unsupported Features

Code Access Security was greatly developed in this release, but a couple of JIT supporting routines are still missing, and no audit has been done of the class libraries and the runtime to advertise it as a working feature.

See the slides from security presentation at the Mono meeting for details.


Mono is now relocatable. This means that a Mono package or RPM can be relocated to any directory and will continue to work. This works on Linux systems and Solaris 10.

Important: If you embed Mono, you must now call the can call instead mono_assembly_setrootdir($libdir) and mono_set_config_dir ($sysconfdir) to set the library directory and the system configuration directories.

Changes since Mono 1.1.18

Serialization callbacks, allows for version-resistant serialization [Robert Jordan].

The Registry now supports machine-level settings [Miguel de Icaza].

Installing Mono 1.2

	$ ./configure --prefix=/devel

Binary Packages and Source Code Downloads:

Source code and pre-compiled packages for SUSE, SLES, Fedora Core 3, 4, Solaris, RHEL, MacOS and Windows in a variety of platforms available from our web site from the download section.

Quick source code installation:

If we have no packages for your platform, installing from source code is very simple.


    $ tar xzf mono-1.2.0tar.gz
    $ cd mono-1.2.0
    $ ./configure
    $ make
    $ make install

Then compile libgdiplus:

    $ tar xzf libgdiplus-1.2.0.tar.gz
    $ cd libgdiplus-1.2.0
    $ ./configure
    $ make
    $ make install

Previous Release Notes

All of the changes since 1.0 are documented in the following release notes: 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 1.1.6, 1.1.7, 1.1.8, 1.1.9, 1.1.10, 1.1.13, 1.1.14, 1.1.15, 1.1.16, 1.1.17 and 1.1.18.

This release is mostly a bug-fix release, there are very few new developments.


The following is a partial list of contributors to the 1.2 release of Mono, if your name is missing, please contact us.

Aaron Bockover, Aaron Flynt, Aaron Tomb, Adhamh Findlay, Adrian Johnson, Akiramei, Aleksandar Dezelin, Alexander Larsson, Alexander Olk, Alexandre Gomes, Alexandre Miguel, Alexandre Rocha Lima e Marcondes, Alex Graveley, Alois Bělaška, Alp Toker, Andreia Gaita, Andrew Skiba, Anil Bhatia, Ankit Jain, Atsushi Enomoto, B Anirban, Behdad Esfahbod, Ben Maurer, Ben Motmans, Bernie, Bernie Solomon, Bill Middleton, Billy Biggs, Blagovest Dachev, Boris Kirzner, Brian Crowell, Brian Ritchie, Brion Vibber, Bryan Worth, Carlos Alberto, Carlos Alberto Cortés, Carlos Guzmán, Carl Worth, Cesar Octavio López Natarén,, Chris Lahey, Chris Micacchi, Christian Biesinger, Christian Hergert, Chris Toshok, Chris Turchin, C.J. Collier, Daniel Drake, Daniel Granath, Daniel Morgan, Daniel Rodriguez, Dan Winship, David Hudson, David Sheldon, David Waite, Dean Brettle, Dennis Hayes,,, Dick Porter, Duncan Mak, Eduardo Garcia Cebollero, Eric Butler, Erik Dasque, Everaldo Canuto, Eyal Alalouf, Fawad Halim, Felipe Lessa, Florian Gross, Francisco Figueiredo Jr., Francisco T. Martinez, Gary Ekker, Geoff Norton, Gert Driesen,, Gonzalo Paniagua Javier, Greg Lonnon, Gustavo Giraldez, Guy Cohen, Haakon Nilsen, Hagit Yidov, Hiroyuki Ishimine, Hisham Mardam Bey, Hubert FONGARNAND, Hye-Shik Chang, Iain McCoy, Idan Gazit, Igor Zelmanovich, Ilya Kharmatsky, Ingmar Schuster, Itamar Rogel, Jackson Harper, Jacob Ilsø Christensen, Jaen Saul, Jakub Boqusz, Jambunathan K, James Willcox, Jarosław Pawlak, Jb Evain, Jelmer Vernooij, Jeroen Zwartepoorte, Joachim Ante, Jochen Wezel, Joergr Rosenkranz, Joe Shaw, John BouAntoun, John Ehresman, John Luke, Jonathan Chambers, Jonathan Gilbert, Jonathan Pobst, Jonathan Pryor, Jonathan S. Chambers, Jon Larimer, Jon Trowbridge, Joost Evertse, Jordi Má, Jörg Rosenkranz, José Alexandre Antunes, Joseph Hill, Josh Cooley, Joshua Tauberer,, Julien Puydt, Juraj Skripsky, Kamil Skalski, Kazuki Oikawa, Klain Yoni, Konstantin Triger, Kornél Pál, Larry Ewing, Leszek Ciesielski, Lluis Sanchez, Lluis Sanchez Gual, Luke Ravitch, Maksim Vorobiev, Manjula MGH, Marc Haisenko, Marek Habersack, Marek Safar, Marek Sieradzki, Mario Sopena Novales, Mark Crichton, Martin Baulig, Martin Kretzschmar, Martin Willemoes Hansen, Mart Raudsepp, Mart Roosmaa, Massimiliano Mantione, Matt Hargett, Matthew Wright, Matthias Felgner, Maverson Eduardo Schulze Rosa, meebey (, Merav Sudri, Michael Hutchinson, Michael Meeks, Michal Moskal, Miguel de Icaza, Mike Kestner, Mike Tindal, Mike Welham, Nagappan A, Neale Ferguson, Nick Drochak, Nigel Benns, Oleg Mihailik, Palaniappan, Paolo Molaro, Patrick Michel, Patrik Torstensson, Pedro Gomes, Pedro Kiefer, Pedro Martinez, Peter Bartok, Peter Dennis Bartok, Peter Dettman, Peter Johanson, Peter Williams, Petri Latvala, Rafael Ferreira, Rafael Mizrahi, Rafael Teixeira, Raja R Harinath, Randy Ridge, Raphael Slinckx, Ravindra Kumar, Ray Molenkamp, Ricardo Fernandez Pascual, Ritvik Mayank, Robert Jordan, Roberto Costa, Rob Lyon,, Roei Erez, Rolf Bjarne Kvinge, Roozbeh Pournader, Sachin Kumar, Sanjay Gupta, Sathya Sudha, Sebastien Pouliot, Sebastien Robitaille, Sebastien (, Senganal T, Sergey Tikhonov, Shane Landrum, (Sebastian),, Sridhar Kulkarni, Sudha, Sudharsan V, Sudha Sathya, S Umadevi, Suresh Kumar, Suresh Thangavel, Svetlana Zholkovsky, Tal Klahr, Tambet Ingo, The Software Team (, Thomas Zoechling, Thong Nguyen, Tobias Käs, Toby Miller, Todd Berman, Tomas Kukol, Tomasz Cholewo, Tor Lillqvist, T Senganal, Urs Muff, Vladimir Krasnov, Vladimir Vukicevic, Vladislav Spivak, Wade Berrier, Yaacov Akiba Slama, Yoni Klain, Zac Bowling and Zoltan Varga.