RFR(M): 8204965: Fix '--disable-cds' and disable CDS on AIX by default

[Jiangli Zhou]

Hi Volker,

The changes look good to me overall. I’ll refer to the JVMTI experts for jvmtiEnv.cpp change. I have a question for the change in vmStructs.cpp. Any reason why only _current_info needs CDS_ONLY?

   /********************************************/                                                                                     \
   /* FileMapInfo fields (CDS archive related) */                                                                                     \
   /********************************************/                                                                                     \
                                                                                                                                      \
   nonstatic_field(FileMapInfo,                 _header,                                       FileMapInfo::FileMapHeader*)           \
-     static_field(FileMapInfo,                 _current_info,                                 FileMapInfo*)                          \
+     CDS_ONLY(static_field(FileMapInfo,        _current_info,                                 FileMapInfo*))                         \
   nonstatic_field(FileMapInfo::FileMapHeader,  _space[0],                                     FileMapInfo::FileMapHeader::space_info)\
   nonstatic_field(FileMapInfo::FileMapHeader::space_info, _addr._base,                        char*)                                 \
   nonstatic_field(FileMapInfo::FileMapHeader::space_info, _used,                              size_t)                                \
                                                                                                                                      \
Thanks,
Jiangli

> On Jun 14, 2018, at 7:26 AM, Volker Simonis <volker.simonis at gmail.com> wrote:
> 
> Hi,
> 
> can I please have a review for the following fix:
> 
> http://cr.openjdk.java.net/~simonis/webrevs/2018/8204965/
> https://bugs.openjdk.java.net/browse/JDK-8204965
> 
> CDS does currently not work on AIX because of the way how we
> reserve/commit memory on AIX. The problem is that we're using a
> combination of shmat/mmap depending on the page size and the size of
> the memory chunk to reserve. This makes it impossible to reliably
> reserve the memory for the CDS archive and later on map the various
> parts of the archive into these regions.
> 
> In order to fix this we would have to completely rework the memory
> reserve/commit/uncommit logic on AIX which is currently out of our
> scope because of resource limitations.
> 
> Unfortunately, I could not simply disable CDS in the configure step
> because some of the shared code apparently relies on parts of the CDS
> code which gets excluded from the build when CDS is disabled. So I
> also fixed the offending parts in hotspot and cleaned up the configure
> logic for CDS.
> 
> Thank you and best regards,
> Volker
> 
> PS: I did run the job through the submit forest
> (mach5-one-simonis-JDK-8204965-20180613-1946-26349) but the results
> weren't really useful because they mention build failures on linux-x64
> which I can't reproduce locally.