构建Jvm环境

Linux环境下

准备环境

需要安装高版本JDK 推荐 JDK 16+

需要编译的jdk下载下来

git clone https://git.openjdk.java.net/jdk/

环境安装

# 下载openjdk16
 # https://jdk.java.net/16/
 wget https://download.java.net/java/GA/jdk16.0.2/d4a915d82b4c4fbb9bde534da945d746/7/GPL/openjdk-16.0.2_linux-x64_bin.tar.gz

 # 安装openJdk16 / 如果在后面的编译中报错，就换高版本JDK
 sudo mkdir -p /usr/java/openjdk
 sudo cp openjdk-16.0.2_linux-x64_bin.tar.gz  /usr/java/openjdk/openjdk-16.0.2_linux-x64_bin.tar.gz 
 cd /usr/java/openjdk
 sudo tar -xzvf openjdk-16.0.2_linux-x64_bin.tar.gz

 #部署环境
 sudo nano /etc/profile
 ## 在文件尾部添加
 # OpenJDK 16.0.2
 JAVA_HOME=/usr/java/openjdk/jdk-16.0.2
 PATH=$PATH:$HOME/bin:$JAVA_HOME/bin
 export JAVA_HOME
 export PATH

 # Ctrl +o回车保存，ctrl+x离开；
 source /etc/profile 

 # 安装编译jdk要求的依赖
 sudo apt-get install build-essential gawk m4 libasound2-dev libcups2-dev libxrender-dev xorg-dev xutils-dev binutils libmotif-dev ant autoconf unzip zip

 #卸载openjdk 11
 sudo apt-get remove openjdk*
 sudo source /etc/profile

进入git clone 后的目录 cd jdk
开始编译
```
   bash configure
```

如果正常会显示如下（非正常按照提示apt install缺失依赖即可）

   #示例
   Configuration summary:
   * Debug level:    fastdebug
   * HS debug level: fastdebug
   * JVM variants:   server
   * JVM features:   server: 'aot cds cmsgc compiler1 compiler2 epsilongc g1gc graal jfr jni-check jvmci jvmti management nmt parallelgc serialgc services shenandoahgc vm-structs zgc'
   * OpenJDK target: OS: linux, CPU architecture: x86, address length: 64
   * Version string: 12-internal+0-adhoc.weizhishang.jdk12-06222165c35f (12-internal)

   Tools summary:
   * Boot JDK:       openjdk version "11.0.10" 2021-01-19 OpenJDK Runtime Environment (build 11.0.10+9-Ubuntu-0ubuntu1.18.04) OpenJDK 64-Bit Server VM (build 11.0.10+9-Ubuntu-0ubuntu1.18.04, mixed mode, sharing)  (at /usr/lib/jvm/java-11-openjdk-amd64)
   * Toolchain:      gcc (GNU Compiler Collection)
   * C Compiler:     Version 7.5.0 (at /usr/bin/gcc)
   * C++ Compiler:   Version 7.5.0 (at /usr/bin/g++)

   Build performance summary:
   * Cores to use:   3
   * Memory limit:   3932 MB

最后进行编译，去喝杯咖啡，这个过程得十几分钟
```
   make images
```
没有报错的话，测试下编译后的jdk版本
```
./build/*/images/jdk/bin/java -version
```
基本测试
```
make run-test-tier1
```

## Linux增强

# 修改镜像源 Ubuntu 20.04 LTS
/etc/apt/sources.list

# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse

导入到Clion

在项目根目录新加CMakeLists.txt：

cmake_minimum_required(VERSION 3.7)
project(hotspot)

include_directories(
		src/hotspot/cpu
		src/hotspot/os
		src/hotspot/os_cpu
		src/hotspot/share
		src/hotspot/share/precompiled
		src/hotspot/share/include
		src/java.base/unix/native/include
		src/java.base/share/native/include
		src/java.base/share/native/libjli
)

file(GLOB_RECURSE SOURCE_FILES "*.cpp" "*.hpp" "*.c" "*.h")
add_executable(hotspot ${SOURCE_FILES})