De-universalizing hotspot in jdk8u
astrange at apple.com
Mon Jan 12 19:20:09 UTC 2015
> On Jan 12, 2015, at 3:26 AM, David Holmes <david.holmes at oracle.com> wrote:
> cc'ing macosx-port-dev and hotspot-dev
> On 12/01/2015 8:41 PM, Erik Joelsson wrote:
>> On 2015-01-12 00:02, David Holmes wrote:
>>> Hi David,
>>> On 10/01/2015 2:00 AM, David DeHaven wrote:
>>>> 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.
> David H.
I did the original universal binary work for hotspot when bringing up macosx-port.
At the time we were building and testing JDK 7 as universal (i386+x86-64) since e.g. some apps had JNI code that was only built 32-bit.
The other jdk components didn't need any makefile work, because the compiler can build them universal by itself, but hotspot autogenerates a lot of arch-specific code and it was easier to build it twice and glue them together in the makefile.
As long as Java is only been shipped 64-bit these days, I personally don't see a reason to keep it.
>>> David H.
>>>> Quite frankly I'd rather just remove all the universal binary stuff
>>>> from hotspot, but I'm trying my best to minimize the changes there...
>>>> the "other" problem I can handle easily.
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