The follow packages has limits in in version 0.44. A possible newer version of this list can you find in the news area.
com.sun.security.auth.module
Not implemented.
java.applet
GNU Classpath implementation. Not implemented.
java.awt
Mostly implemented with System.Windows.Forms based back-end. Limited support*.
java.io.Console
Not implemented.
java.lang.instrument
Not implemented.
java.lang.management
Not implemented.
java.net
No IPv6 support implemented. (since 0.45 also IPv6 support)
java.net.ProxySelector
Getting the default system proxy for a URL is not implemented.
java.text.Bidi
GNU Classpath implementation. Limited support*.
java.util.zip
Partially based on GNU Classpath implementation. Limited support*
javax.management
Not implemented.
javax.print
Mostly implemented. Limited support*.
javax.script
Not implemented.
javax.smartcardio
Not implemented.
javax.sound
Not implemented.
javax.swing
Mostly implemented. Limited support*.
javax.tools
Not implemented.
org.ietfs.jgss
Not implemented.
sun.net.www.content.audio
Audio content handlers not implemented.
sun.net.www.content.image
Image content handlers not implemented.
There is a tool that compare the available classes in Java and IKVM. It used the follow skip list.
command meaning
A line with comments
-file
The follow lines contains jar files that are not part of IKVM.
-package
The follow lines contains packages that are not part of IKVM. This is also valid for sub packages.
-class
The follow lines contains classes that are not part of IKVM.
-resource
The follow lines contains resources that are not part of IKVM.