We need to store extended meta-data in module-infoc.class to record the platform cases where modules are platform specific. For now, we are using a prototype class file attribute with name "TargetPlatform" that can be used to record the operating system name, architecture and version, similar to the os.name, os.arch and os.version system properties.

The prototype attribute is very simple and just contains indexes to 3 x UTF-8 strings. The values are optional, the index can be 0.

     * TargetPlatform_attribute {
     * // index to CONSTANT_utf8_info structure in constant pool representing
     * // the string "TargetPlatform"
     * u2 attribute_name_index;
     * u4 attribute_length;
     *
     * // index to CONSTANT_CONSTANT_utf8_info structure with the OS name
     * u2 os_name_index;
     * // index to CONSTANT_CONSTANT_utf8_info structure with the OS arch
     * u2 os_arch_index
     * // index to CONSTANT_CONSTANT_utf8_info structure with the OS version
     * u2 os_version_index;
     * }

This issue tracks updating javap and the classfile code to support this attribute.

This task is not critical and okay to wait until there is further discussion/decisions on extended meta data before adding support for this. In the mean-time, the jmod tool will add this attribute to the JMOD files created in the build as we need this attributes to create the target runtime image and to ensure that we never attempt to link modules for different target platforms together.