Thanks for the clarification Jonathan. Regards, Volker
On Tue, Nov 4, 2014 at 4:05 PM, Jonathan Gibbons <jonathan.gibb...@oracle.com> wrote: > On 11/04/2014 01:55 AM, Volker Simonis wrote: >> >> Hi, >> >> first of all I'm not Jigsaw expert in any way so if this question has >> been discussed/answered before please be so kind to point me to the >> right link. >> >> I've just skimmed JEP 220 and it is not clear to me how the removal of >> rt.jar/tools.jar will affect the compilation with "-source -target >> -bootclasspath". As far as I know one should always use a >> corresponding "-bootclasspath" option if compiling with "-target". >> This is for example done in the JDK build during boot-strapping. >> >> Until now, it was easy to set the bootclasspath for Oracle/OpenJDK >> because all the relevant classes were contained in rt.jar. But this is >> already quite complicated with other JDKs (i.e. IBM J9) which already >> packed the standard java classes in various different jar files (see >> for example "8026964: Building with an IBM J9 boot jdk requires >> special settings for BOOT_RTJAR" - >> https://bugs.openjdk.java.net/browse/JDK-8026964). >> >> For the current build system, I found that with the JDKs I use this >> problem can be easily solved by using the "sun.boot.class.path" >> system property which contains all the relevant jar files (see >> >> http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2013-November/thread.html#1222 >> and http://cr.openjdk.java.net/~simonis/webrevs/8026964.v2/). >> Unfortunately, this change is still not committed:) >> It is not clear to me from reading JEP 220 if "sun.boot.class.path" >> will be removed or if it will only contain other content and how t hat >> could be used in this context. >> >> So my questions are: >> 1. How will it be possible to bootstrap JDK9 with JIGSAW if the JDK9 >> tools like javac won't support -bootclasspath with jar files (or will >> they still support them)? >> 2. How will it be possible with a JDK > 9 to produce JDK9 classes with >> "-target 9" without a possibility to supply the corresponding rt.jar >> as argument to "-bootclasspath"? >> 3. Will JDK9 and above provide a standardized way to specify the >> required classes which are needed in order to compile for a lower JDK >> version (e.g with the help of "jrt:/$MODULE")? Will there be a >> standardized set of modules which have to contain all the required >> boot classes? >> >> Thank you and best regards, >> Volker > > > Volker, > > With respect to javac, we intend to continue to support -bootclasspath as > now for supported values of -target earlier than JDK 9. And going forward, > there will need to be a "modular equivalent" for -bootclasspath for values > of -target for JDK 9 and later. > > -- Jon
