# Monday, October 31, 2011
New Development Snapshot

Fixed the remaining known OpenJDK 7 issues, apart from method overriding, which finally made it into the JVM spec (section 5.4.5), but it's not clear yet what the actual behavior should be. It's a little ridiculous, but almost 16 years after the release of Java 1.0 a fundamental part of the JVM is still poorly documented and implemented.


  • Added ikvmc -platform:arm and -platform:anycpu32bitpreferred options.
  • Bug fix. Make sure sun.misc.Launcher is initialized before setting a security manager, because Launcher assumes there is no security manager yet.
  • Added ikvmstub -forwarders option to support ".NET Core profile" assemblies.
  • Implemented com.sun.security.auth.module.NTSystem.getCurrent().
  • Fixed Throwable.fillInStackTrace() to respect non-writeable stack trace.
  • Fixed Throwable deserialization issues introduced with OpenJDK 7.
  • Fixed Throwable.getSuppressed() to return a global empty array (OpenJDK tests depend on that).
  • Fixed java.lang.ProcessImpl pipe to flush writes.
  • Fixed java.lang.ProcessImpl.openForAtomicAppend() to actually use atomic append.
  • Fixed java.lang.ProcessImpl to clear out the existing environment variables when an envblock is specified.
  • Implemented java.lang.ProcessImpl redirectErrorStream for case where stdout is not also redirected.
  • Fixed core library build issue. java.lang.AutoCloseable.close() method may be used before it has been linked.
  • Bug fix. When calling a final method on a remapped type we can't call the instance method in the remapped type, but we have to call the instancehelper instead.
  • Starting with class file version 51 the <clinit> methods need to be static.
  • Added java.nio.file security manager checks.
  • Added workaround for another x64 JIT bug.
  • IKVM.Reflection: Added .NET 4.5 metadata enum values.
  • IKVM.Reflection: Added support for PortableExecutableKinds.Preferred32Bit.
  • IKVM.Reflection: Added support for process architecture in assembly flags.

Binaries available here: ikvmbin-7.0.4321.zip

Monday, October 31, 2011 12:01:05 PM (W. Europe Standard Time, UTC+01:00)  #    Comments [4]
# Monday, October 10, 2011
Windows Runtime (aka WinRT) Thoughts


After the Build keynote many people were confused. I think there were three main reasons for that: 1) Metro Style Apps and Windows Runtime APIs were introduced together, 2) marketing had banned the mention of COM and 3) Windows Runtime is a bad name.

As the conference progressed and people had time to ask more questions and attend more sessions things became a bit clearer. If you haven't already done so, please read Miguel's blog entry about WinRT.

Let's dive deeper into the three points of confusion:

  1. Metro Style Apps and Windows Runtime are two orthogonal concepts.
    I expect some people to take issue with this, but the reality is that Metro is a new application model and WinRT is a new way of exposing Windows APIs. They are completely orthogonal. To be clear, most new WinRT APIs are only usuable from Metro Style Apps, but that is simply a consequence of the fact that many new APIs were added to support Metro and WinRT is the obvious way to do it.
    It should be obvious by now, but I'll explicitly mention it. Some WinRT APIs are usable from non-Metro apps and some Win32 APIs are useable from Metro apps.
  2. WinRT is an evolution of COM. IMO, if they had mentioned this during the keynote, there would have been a lot less confusion. However, marketing had apparently found that people don't like COM and so it was decided that this should not be mentioned, of course during subsequent talks it quickly became obvious anyway.
  3. The Runtime in "Windows Runtime" is like the Runtime in "C runtime library", not like the Runtime in "Common Language Runtime". The Windows Runtime is not an execution environment, just a set of APIs and a way of exposing these APIs (and your own APIs using a similar mechanism).

What About .NET?

Like COM, Windows Runtime APIs can be used from different languages (but the language needs to do some work to enable this). Microsoft supports using WinRT APIs from C/C++, Javascript and C#/VB. All of these languages were modified to support this. Not all .NET languages automatically get full support for WinRT, for example there is currently no first class WinRT support in F#.

Some people thought that .NET was going to be replaced by WinRT (probably due to reason 3 above), but this clearly doesn't make sense.

Something of interest from a .NET point of view is that instead of type libraries WinRT uses the .NET (ECMA CLI) metadata format to describe the APIs. I made a couple of minor tweaks to IKVM.Reflection to better support this.

What About IKVM.NET?

I have not yet investigated exactly what is needed for WinRT support in IKVM.NET, but it is very likely that WinRT support will arrive some time before Windows 8 is released.

Note however that running IKVM.NET inside Metro Style Apps will not be supported, because the .NET Metro profile is very limited. Hopefully more about this in a future blog entry.

Recommended Viewing

Lap around the Windows Runtime
Windows Runtime internals: understanding "Hello World"
Ten Tips When Writing a Hybrid Language Metro style Application (this title is very misleading, it really is about the design of WinRT)

Monday, October 10, 2011 11:10:17 AM (W. Europe Daylight Time, UTC+02:00)  #    Comments [1]
# Friday, October 7, 2011
New Development Snapshot

Time for a new snapshot. With the (more or less) completion of java.nio.file the release is getting closer. There are still some minor issues, but the bulk of the work is now complete.


  • Fixed ikvmstub to handle annotation defaults.
  • Fixed ikvmc to generate (private) setter for final instance fields that get an access stub to support serialization and reflection.
  • Runtime.exec() fix. When disambiguating executable names, we should only try to append .exe if the filename doesn't already contain a dot.
  • Removed unnecessary link demand from MappedByteBuffer that caused problems when building for .NET 4.0.
  • Fixed MethodHandle constructor invocation issue when running on .NET 4.0.
  • Removed mapping of System.Security.VerificationException to java.lang.VerifyError.
  • Fixed os.name and os.version system properties when running on unknown Windows version (Windows 8).
  • Bug fix. IPInterfaceProperties.GetIPv_Properties() can throw an exception (and does so on Windows 8 for some interfaces).
  • Fixed ikvmc to not open the remap file with write access.
  • Implemented remaining java.nio.file functionality (minus most optional functionality and ACL support).
  • IKVM.Reflection: Implemented ToString() for EventInfo and PropertyInfo.
  • IKVM.Reflection: Copy all assembly flags when adding an assembly reference (WinRT fix).
  • IKVM.Reflection: Added API extension to query and define custom attributes on interfaceimpl records.
  • IKVM.Reflection: Added support for targetting ARM.
  • IKVM.Reflection: Added ILGenerator.__StackHeight property API extension.

Binaries available here: ikvmbin-7.0.4296.zip

Friday, October 7, 2011 12:38:26 PM (W. Europe Daylight Time, UTC+02:00)  #    Comments [0]