增加了JVM虚拟机的第一章笔记

后端/JVM虚拟机/1.走进JVM.md

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+>[TOC]
+
+# 编译JVM遇见的问题
+
+环境：ubuntu20.04TSL
+
+## 1、安装gcc
+
+```shell
+sudo apt-get install build-essential
+```
+
+## 2、接着安装以下依赖库：
+
+| 命令                                                         | 工具       |
+| ------------------------------------------------------------ | ---------- |
+| sudo apt-get install libfreetype6-dev                        | FreeType   |
+| sudo apt-get install libcups2-dev                            | CUPS       |
+| sudo apt-get install libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev | X11        |
+| sudo apt-get install libasound2-dev                          | ALSA       |
+| sudo apt-get install libffi-dev                              | libffi     |
+| sudo apt-get install autoconf                                | Autoconf   |
+| sudo apt-get install libfontconfig1-dev                      | fontconfig |
+
+## 3、安装JDK11
+
+由于openjdk很多部分由java实现的，假设需要编译的版本为N，需要装一个版本号大于等于N-1的jdk，我们需要编译openjdk12，所以需要装JDK11及之后的版本，命令如下：
+
+```shell
+sudo apt-get install openjdk-11-jdk
+```
+
+## 4、编译
+
+```shell
+# 1.检查编译环境
+bash configure --enable-debug --with-jvm-variants=server
+# 2.显示如下代码
+
+A new configuration has been successfully created in
+/home/xiang/win_d/java/jdk12-06222165c35f/build/linux-x86_64-server-fastdebug
+using configure arguments '--enable-debug --with-jvm-variants=server'.
+
+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.xiang.jdk12-06222165c35f (12-internal)
+
+Tools summary:
+* Boot JDK:       openjdk version "11.0.7" 2020-04-14 OpenJDK Runtime Environment (build 11.0.7+10-post-Ubuntu-3ubuntu1) OpenJDK 64-Bit Server VM (build 11.0.7+10-post-Ubuntu-3ubuntu1, mixed mode, sharing)  (at /usr/lib/jvm/java-11-openjdk-amd64)
+* Toolchain:      gcc (GNU Compiler Collection)
+* C Compiler:     Version 9.3.0 (at /usr/bin/gcc)
+* C++ Compiler:   Version 9.3.0 (at /usr/bin/g++)
+
+Build performance summary:
+* Cores to use:   4
+* Memory limit:   7858 MB
+
+# 3.接着执行
+make images
+
+# 4.报错
+ERROR: Build failed for target 'images' in configuration 'linux-x86_64-server-fastdebug' (exit code 2) 
+Stopping sjavac server
+
+=== Output from failing command(s) repeated here ===
+* For target hotspot_variant-server_libjvm_objs_arguments.o:
+In file included from /usr/include/string.h:495,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/utilities/globalDefinitions_gcc.hpp:35,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/utilities/globalDefinitions.hpp:32,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/utilities/align.hpp:28,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/runtime/globals.hpp:29,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/memory/allocation.hpp:28,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/classfile/classLoaderData.hpp:28,
+                 from /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/precompiled/precompiled.hpp:34:
+In function ‘char* strncpy(char*, const char*, size_t)’,
+    inlined from ‘static jint Arguments::parse_each_vm_init_arg(const JavaVMInitArgs*, bool*, JVMFlag::Flags)’ at /home/xiang/win_d/java/jdk12-06222165c35f/src/hotspot/share/runtime/arguments.cpp:2472:29:
+/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:34: error: ‘char* __builtin_strncpy(char*, const char*, long unsigned int)’ output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
+  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
+   ... (rest of output omitted)
+
+* All command lines available in /home/xiang/win_d/java/jdk12-06222165c35f/build/linux-x86_64-server-fastdebug/make-support/failure-logs.
+=== End of repeated output ===
+
+No indication of failed target found.
+Hint: Try searching the build log for '] Error'.
+Hint: See doc/building.html#troubleshooting for assistance.
+
+```
+
+## 5、解决问题
+
+1. gcc和g++版本过高，需要更换版本
+
+```shell
+# 1.安装gcc7
+sudo apt-get install gcc-7 gcc-7-multilib g++-7 g++-7-multilib
+
+# 2.查看gcc和g++分别有那些软件:
+ll /usr/bin/gcc*
+ll /usr/bin/g++*
+
+# 3.最后将/usr/bin下面以下文件通过软连接重新指向版本7
+/usr/bin/gcc
+/usr/bin/gcc-ar
+/usr/bin/gcc-nm
+/usr/bin/gcc-ranlib
+/usr/bin/g++ 
+```
+
+2. 执行shell脚本
+
+```shell
+
+COMMAND=(/usr/bin/gcc /usr/bin/gcc-ar /usr/bin/gcc-nm /usr/bin/gcc-ranlib /usr/bin/g++)
+
+for command in "${COMMAND[@]}"
+do
+  rm $command
+  ln -s "$command"-7 $command
+done
+
+```
+
+3. 重新编译
+
+```shell
+make clean
+make dist-clean
+
+bash configure --enable-debug --with-jvm-variants=server
+make images
+```
+
+输出一下内容编译成功
+
+![image-20211201101145958](assets/image-20211201101145958.png)