Review request: Zero assembler port

[Gary Benson]

Hi all,

I had an email this morning from someone whose build was breaking
because of unset environment variables so I wanted to mail a small
clarification.

  * To build Zero there are nine environment variables that need
    setting before make runs:

      CORE_BUILD
      ZERO_BUILD
      ZERO_LIBARCH
      ZERO_ARCHDEF
      ZERO_ENDIANNESS
      ZERO_BITSPERWORD
      ZERO_ARCHFLAG
      LIBFFI_CFLAGS
      LIBFFI_LIBS

  * If you are using jdk/make/jdk_generic_profile.sh then all but
    the first two will be set for you.  You would build like this:

      export CORE_BUILD=true
      export ZERO_BUILD=true
      . jdk/make/jdk_generic_profile.sh
      make

  * If you are not using jdk/make/jdk_generic_profile.sh then you
    must set all nine yourself.

Cheers,
Gary

Gary Benson wrote:
> Hi all,
> 
> Zero is an interpreter-only port of HotSpot that uses no assembler and
> can trivially be built on any Linux system.  The following webrev adds
> Zero support to OpenJDK:
> 
>   http://cr.openjdk.java.net/~gbenson/zero-03/
> 
> In order to enable the Zero build, the following environment variables
> must be set:
> 
>   CORE_BUILD
>     Setting CORE_BUILD to "true" will result in an interpreter-only
>     HotSpot being built, with neither the client nor the server
>     compilers.  If CORE_BUILD is unset, or set to any other value
>     than "true", then the compiler(s) will be built as normal.
> 
>   ZERO_BUILD
>     Setting ZERO_BUILD to "true" will cause the Zero interpreter to
>     be used.  If ZERO_BUILD is unset, or set to any other value than
>     "true", the standard, platform-specific interpreter will be used.
> 
> The reason for having two separate flags is to allow for Zero builds
> with JIT compilers such as Shark (not included in this webrev).  To
> build HotSpot with Zero and Shark you would set ZERO_BUILD to "true"
> but leave CORE_BUILD unset.
> 
> There are five variables which are required when ZERO_BUILD is set to
> "true".  These are set by jdk/make/jdk_generic_profile.sh based on the
> result of uname -m:
> 
>   ZERO_LIBARCH
>     This is the name of the architecture-specific subdirectory under
>     $JAVA_HOME/jre/lib.  Typically this will be the same as the output
>     of uname -m, although there are some exceptions: "amd64" instead
>     of "x86_64", for example, and "i386" instead of "i686".
> 
>   ZERO_ARCHDEF
>     The value of ZERO_ARCHDEF will be passed to the C++ compiler using
>     -D${ZERO_ARCHDEF} to allow conditionalized platform-specific code.
>     This is typically set to ZERO_LIBARCH converted to uppercase but,
>     again, there are exceptions.  "i386" becomes "IA32", to match what
>     HotSpot already does, and on platforms with both 32- and 64-bit
>     variants ZERO_ARCHDEF corresponds to the 32-bit version, so both
>     ppc and ppc64 have ZERO_ARCHDEF set to "PPC".
> 
>   ZERO_ENDIANNESS
>     This is set to "little" or "big".
> 
>   ZERO_BITSPERWORD
>     This is set to "32" or "64".
> 
>   ZERO_ARCHFLAG
>     This is a flag that will be passed to the C++ compiler and to the
>     linker to instruct them to generate code for the particular
>     platform.  This is required for platforms with both 32- and 64-bit
>     variants where the compiler needs to be told which variant to
>     build for.  ZERO_ARCHFLAG will typically be set to "-m32" or
>     "-m64", except on 31-bit zSeries where it will be set to "-m31".
> 
> Zero uses one external library, libffi, for JNI method invocation.
> The following two variables are used to tell the compiler and linker
> how to find libffi.  These can be set by the user, but if left unset
> then jdk/make/jdk_generic_profile.sh will attempt to set them using
> pkg-config:
> 
>   LIBFFI_CFLAGS
>     Flags to be passed to the C++ compiler to build against libffi.
> 
>   LIBFFI_LIBS
>     Flags to be passed to the linker to link against libffi.
>     
> Ok, I think that's it!    
> 
> Cheers,
> Gary
>     
> -- 
> http://gbenson.net/