root@ubuntu:/home/gap/jdk8u# make    

WARNING: You have the following ALT_ variables set:
ALT_OUTPUTDIR=/home/gap/build
ALT_ variables are deprecated and will be ignored. Please clean your environment.

Building OpenJDK for target 'default' in configuration 'linux-x86_64-normal-server-fastdebug'

## Starting langtools
/bin/sh: 1: cd: can't cd to /home/gap/jdk8u/langtools/make
/home/gap/jdk8u//make/Main.gmk:84: recipe for target 'langtools-only' failed
make: *** [langtools-only] Error 2

前面参考的JVM那本书上的，本想指定编译输出目录，结果报错。这里也看的出来，因为我以configure配置时，搞成了.

bash ./configure --enable-debug --with-target-bits=64

返工。bash ./configure  --with-target-bits=64

root@ubuntu:/home/gap/jdk8u# make clean
Cleaning langtools build artifacts ... done
Cleaning corba build artifacts ... done
Cleaning jaxp build artifacts ... done
Cleaning jaxws build artifacts ... done
Cleaning hotspot build artifacts ... done
Cleaning jdk build artifacts ... done
Cleaning nashorn build artifacts ... done
Cleaning images build artifacts ... done
Cleaning overlay-images build artifacts ... done
Cleaning bootcycle-build build artifacts ... done
Cleaning docs build artifacts ... done
Cleaning docstemp build artifacts ... done
Cleaning testoutput build artifacts ... done
Cleaned all build artifacts.

root@ubuntu:/home/gap/jdk8u# bash ./configure  --with-target-bits=64
bash: ./configure : No such file or directory

操，configure文件都不在了。

root@ubuntu:/home/gap/jdk8u# make help

OpenJDK Makefile help
=====================

Common make targets
.  make [default]         # Compile all product in langtools, hotspot, jaxp, jaxws,
.                         # corba and jdk
.  make all               # Compile everything, all repos and images
.  make images            # Create complete j2sdk and j2re images
.  make docs              # Create javadocs
.  make overlay-images    # Create limited images for sparc 64 bit platforms
.  make profiles          # Create complete j2re compact profile images
.  make bootcycle-images  # Build images twice, second time with newly build JDK
.  make install           # Install the generated images locally
.  make clean             # Remove all files generated by make, but not those
.                         # generated by configure
.  make dist-clean        # Remove all files, including configuration
.  make help              # Give some help on using make
.  make test              # Run tests, default is all tests (see TEST below)

Targets for specific components
(Component is any of langtools, corba, jaxp, jaxws, hotspot, jdk, nashorn, images, overlay-images, docs or test)
.  make <component>       # Build <component> and everything it depends on. 
.  make <component>-only  # Build <component> only, without dependencies. This
.                         # is faster but can result in incorrect build results!
.  make clean-<component> # Remove files generated by make for <component>

Useful make variables
.  make CONF=             # Build all configurations (note, assignment is empty)
.  make CONF=<substring>  # Build the configuration(s) with a name matching
.                         # <substring>

.  make LOG=<loglevel>    # Change the log level from warn to <loglevel>
.                         # Available log levels are:
.                         # 'warn' (default), 'info', 'debug' and 'trace'
.                         # To see executed command lines, use LOG=debug

.  make JOBS=<n>          # Run <n> parallel make jobs
.