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Mono on i Project October 13, 2018

10/13/18 Binary Preview Package Notes and Instructions

The Mono on i Project began porting Mono to PASE on IBM i on January 19, 2018. There are still numerous bugs to fix, and the port is hardly production-ready as of yet. However, progress has been made at a very rapid pace, and we would like others to try it out and report problems. We encourage users to report issues to the Mono on i Project by opening an issue at our GitHub issue tracker.


Changes in the 10/13/18 release

  • Updated to latest changeset.

Changes in the 7/6/18 release

  • Updated to latest changeset.

  • Issues with System.Decimal have been fixed.

  • Issues with System.TimeZoneInfo have been fixed, by including the standard IANA time zone info files with the distribution. The tools to manage the database are also included inside a distribution.

Changes in the 6/26/18 release

  • Updated to latest changeset. Upstream has done significant work, including progress towards Roslyn on PowerPC, Span<T> intrinsics, and further integration of the CoreFX platform abstraction layer. CoreFX PAL work will involve heavy work for AIX and PASE integration, and the beginnings of such work have been done.

  • Spurious messages when spawning new threads on AIX have been reduced.

  • System.Diagnostics.Process should function better on AIX.

Changes in the 4/28/18 release

  • Updated to latest changeset. Note upstream is doing refactoring work on tail calls, so we have applied an experimental patch to fix PPC support for such things.

Changes in the 4/15/18 release

  • Updated to latest changeset. This version includes a fixed and upstreamed version of the exceptions issue fixes.

Changes in the 4/10/18 release

  • Updated to latest changeset.

Changes in the 3/27/18 release

  • Updated to latest changeset.

Changes in the 3/13/18 release

  • Updated to latest changeset.

  • BoringTLS is now available, with TLSv1.2 support. Certificates will need to be installed to trust remote sites.

  • An experimental patch to resolve exception crashes in static constructors has been integrated. Thanks to Bernhard for trying to fix this!

Changes in the 2/27/18 release

  • Updated to latest changeset.

  • Async callbacks have been enabled for the runtime.

  • Explicit null checks are always enabled due to null pages..

Changes in the 2/17/18 release

  • Spurious errors with asynchronous threaded I/O have been fixed.

Changes in the 2/14/18 release

  • libintl is properly packaged.

  • In this build, special features allowing the JIT to use new CPU instructions of POWER7 processors have been disabled due to reports of issues when enabled.

Changes in the 2/13/18 release

  • PowerPC processor features are more accurately detected.

  • System.Environment.OSVersion now properly reports the operating system version.

  • Fix a big with getting array sizes.

  • Compatibility issues with i 7.1 have been resolved to the point where the runtime can successfully run programs.

Changes in the 2/7/18 release

Attempting to run Mono on 7.1 resulted in error messages relating to mkdtemp. We discovered that Mono's built in glib has an implementation of mkdtemp, so we modified the code to use that instead.

Required system

Either AIX 6.1 TL9 or i 7.1. The JIT compiler will automatically adjust parameters to optimize for the current CPU. Testing is primarily done on AIX, then on i 7.2, then i 7.1.

It is extremely critical to ensure that the system QCCSID value is properly set. Check your QCCSID value with DSPSYSVAL QCCSID. If it is 65535, please set it to the proper value and sign off and on before installing Mono.

It is strongly recommended that the following IBM LPPs and PTFs are installed:

  • LPP 5733-SC1 OpenSSH/OpenSSL

  • LPP 5733-OPS Open Source Solutions Option 7 (Tools)

  • Open Source Solutions PTF Group SF99123 (7.1), SF99223 (7.2), or SF99725 (7.3) Level 5 (or later)

Included contents

  • Mono (pre-release version 5.13; built from master branch)

  • mcs (non-Roslyn C# compiler; supports C# 7)

  • xbuild (non-Microsoft solution/project make tool)

  • vbnc (non-Roslyn Visual Basic.NET compiler; supports VB 2005, partial VB 2010 support)

  • xsp (stand-alone ASP.NET server)

  • FastCGI Server

  • NUnit (unit testing library and toolchain)

Known issues

Please see the issues page for a list of known issues and to file further ones.

  • FastCGI and mod_mono servers are shipped, but untested. XSP can be used as a development server in the meantime. Be aware that many controls refer to System.Drawing, which means that all but the smallest pages will likely run into the aforementioned problems with System.Drawing.

  • Debug messages such as below will be printed during normal operation. This is expected, often due to semantic differences between other Unices and AIX/PASE. The team is working to resolve these issues.

mono_thread_internal_set_priority: pthread_setschedparam failed, error: 
"Operation not permitted." (1) 
  • Due to differences in how AIX/PASE handle shared libraries, many applications may crash attempting to load native libraries. As such, you may have to alter the application's DLL mappings, either for the assembly in its .config file, or the global /opt/mono/etc/config file. Consult for how DLL mappings work on Mono. Issues with the global DLL mapping are due to packaging toolchain defiencies and will be fixed in a later release.

  • Portions of the standard library may not fully function due to missing support for AIX/PASE. Users are encouraged to report these incidents to the team.

  • Calling between ILE and PASE code is currently not possible. The team expects to eventually solve this problem, but has not crossed that bridge as of this time.

  • We have not attempted to connect to DB2 as of yet. The IBM DB2i .NET provider included within iACS calls into a Win32 DLL, which unfortunately means that we cannot use it on the IBM i. The team is looking into alternative solutions currently.

Installation instructions (on IBM i)

  • The latest release is available from

  • Create an empty save file with which to receive the save file that you downloaded to your PC. To do so, open up a 5250 "green screen" session and run the command CRTSAVF SAVF(QGPL/MONO101318) on your system.

  • Transfer the save file using a command line FTP client in binary mode to QGPL/MONO101318.

  • Restore the Mono on i binaries by running RST DEV('/QSYS.LIB/QGPL.LIB/MONO101318.FILE') OBJ('/QOpenSys/opt/mono') on your system.

  • After unpacking the save file, it is important to make sure that a symbolic link to /QOpenSys/opt is present at /opt. If you have used the YiPS package scripts to install AIX RPMs on PASE, this symbolic link has already been created for you. To check if it exists, run the command WRKLNK '/opt'. If you get "Object not found.", create it by running ADDLNK OBJ('/QOpenSys/opt') NEWLNK('/opt') on your system.

Compile and run your first Mono program

  • A sample "Hello, World!" program is included in /opt/mono/samples/hello.cs

  • To compile it, you can either open a SSH session into a PASE shell, or, less optimally, CALL QP2TERM. Once you are in the PASE shell, run the following commands to make the Mono commands available to your shell:

$ PATH=/opt/mono/bin:$PATH
$ export PATH
  • Copy the hello.cs file from /opt/mono/samples
$ cp /opt/mono/samples/hello.cs hello.cs
  • Now, invoke the Mono C# compiler to compile hello.cs:
$ mcs hello.cs 
  • A file named hello.exe will be created in your current directory. This is a Mono/.NET "managed code assembly" containing the compiled bytecode, much like a Java .JAR file, or a program object. You can even FTP this file to your PC and then run it on Windows. Try it!

  • Now, to run the program:

$ mono hello.exe 

Hello from Mono for the IBM i! 
  • Similarly, you can compile a .NET program on Visual Studio for Windows, copy it to your IBM i system, and run it using the "mono" command. Be aware though, that this may unearth numerous undiscovered bugs in the Mono for IBM i port.

TLS certificates

Out of the box, the runtime's TLS layer won't trust anything due to lacking certificates for it. You can install certificates into Mono using the same tools as Mono uses on other systems.

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