De-universalizing hotspot in jdk8u
david.dehaven at oracle.com
Mon Jan 12 15:17:30 UTC 2015
>>>> We have this nice little comment in common/autoconf/jdk-options.m4:
>>>> # On Macosx universal binaries are produced, but they only contain
>>>> # 64 bit intel. This invalidates control of which jvms are built
>>>> # from configure, but only server is valid anyway. Fix this
>>>> # when hotspot makefiles are rewritten.
>>>> if test "x$MACOSX_UNIVERSAL" = xtrue; then
>>>> So.. I turned it off:
>>>> if test "x$OPENJDK_TARGET_OS" = "xmacosx"; then
>>>> # MACOSX_UNIVERSAL="true"
>>>> And in hotspot/make/bsd/makefiles/defs.make:
>>>> # Universal build settings
>>>> ifeq ($(OS_VENDOR), Darwin)
>>>> # Build universal binaries by default on Mac OS X
>>>> # MACOSX_UNIVERSAL = true
>>>> MACOSX_UNIVERSAL = false
>>>> ifneq ($(ALT_MACOSX_UNIVERSAL),)
>>>> hotspot still seems to build happily (I'm kicking off tests now). Is
>>>> there are particular reason this hasn't been done yet? I'd like to
>>>> know before I pursue this as a means of eliminating our dependency on
>>>> lipo which is causing an inordinate amount of grief when trying to
>>>> build on 10.9 and later when Xcode 5+ is coinstalled. I have some
>>>> logic to work around using the broken /usr/bin/lipo, but it doesn't
>>>> help later in some "other" build target that ends up using '-arch
>>>> i386 -arch x86_64'. It does not explicitly run lipo, it relies on gcc
>>>> to do the fattening itself and so it fails even though I've gone to
>>>> the effort of working around the broken lipo (and it isn't necessary
>>>> anyways because it doesn't even build the i386 binaries even though
>>>> it's supposed to be "universal").
>>> The hotspot makefiles still haven't been rewritten (though Magnus had
>>> been working on it).
>>> Also I was under the impression that we used the universal stuff
>>> because we had to deliver in a particular way on OSX. But I don't know
>>> the details and the people who dealt with the original OSX port effort
>>> are no longer here.
>> I don't know why Hotspot is packaged as a universal binary. In the jdk,
>> only libJObjC was built as a universal binary and that lib was removed
>> before JDK 8 shipped. What part of Macosx would need to interact
>> directly with libjvm.dylib in a way that required a (fake) universal
>> format, but no other libs in the jdk? I would say go ahead and change it.
> In the spirit of "never take down a fence until you know why it was put up in the first place" I've cc'd macosx-port-dev to see if there is anyone around who recalls why hotspot is using the universal binary feature.
I hear you.
My best guess is we'd initially planned on supporting 32 bit but (???) and the easiest way to deliver is in a universal binary. Note that we don't actually deliver universal binaries as the JVM is 64 bit only, or at least there are not nearly enough components there to run a full 32 bit JVM.
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