Currently, the boot layer of the module system is mostly created during the AOT cache assembly phase. However, in the production run, we still have to execute some Java code to finish up its initialization:

https://github.com/openjdk/jdk/blob/8c363b3e3e5c1273a5e9b3393ed09a31b0647a21/src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java#L161

This goal of this RFE is to store the relevant states of the boot layer as part of the AOT cache heap snapshot. For example, the static variable java.lang.System.bootLayer should be initialized and stored as part of the heap snapshot. Therefore, in the production run, we can have the entire module system fully initialized before executing any Java code.

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This RFE is part of the implementation of the Leyden snapshot model -- See JDK-XXXXXXX.