生成boot.art和boot.oat
前面讲的参数中，有一项是--boot-image。我们先看一下这个boot-image是如何编出来的，正好是一个完整的dex2oat的例子.
我们看下在MediaTek MT6753平台下，是如何生成的。
MT6753是64位Cortex-A53的架构，所以boot.art也是64位和32位两套。
64位的boot.art
先看64位的吧：
out/host/linux-x86/bin/dex2oat
--runtime-arg -Xms64m
--runtime-arg -Xmx64m初始堆大小和最大堆大小。
--image-classes=frameworks/base/preloaded-classes预加载类的路径
--dex-file=out/target/common/obj/JAVA_LIBRARIES/core-libart_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/conscrypt_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/okhttp_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/core-junit_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/bouncycastle_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/ext_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/telephony-common_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/voip-common_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/ims-common_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/apache-xml_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/org.apache.http.legacy.boot_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-common_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-framework_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-telephony-common_intermediates/javalib.jar以上是一大堆的dex文件
--dex-location=/system/framework/core-libart.jar
--dex-location=/system/framework/conscrypt.jar
--dex-location=/system/framework/okhttp.jar
--dex-location=/system/framework/core-junit.jar
--dex-location=/system/framework/bouncycastle.jar
--dex-location=/system/framework/ext.jar
--dex-location=/system/framework/framework.jar
--dex-location=/system/framework/telephony-common.jar
--dex-location=/system/framework/voip-common.jar
--dex-location=/system/framework/ims-common.jar
--dex-location=/system/framework/apache-xml.jar
--dex-location=/system/framework/org.apache.http.legacy.boot.jar
--dex-location=/system/framework/mediatek-common.jar
--dex-location=/system/framework/mediatek-framework.jar
--dex-location=/system/framework/mediatek-telephony-common.jar以上是上面那一大堆dex对应的jar文件路径
--oat-symbols=out/target/product/6753_65t_m/symbols/system/framework/arm64/boot.oat符号表的位置
--oat-file=out/target/product/6753_65t_m/dex_bootjars/system/framework/arm64/boot.oat
--oat-location=/system/framework/arm64/boot.oat
--image=out/target/product/6753_65t_m/dex_bootjars/system/framework/arm64/boot.art输出文件有两个：一个是boot.oat，一个是boot.art。
--base=0x70000000基地址0x70000000
--instruction-set=arm64
--instruction-set-variant=cortex-a53
--instruction-set-features=default对于指令架构，除了arm64，更细的是cortex-a53
--android-root=out/target/product/6753_65t_m/system
--include-patch-information
--runtime-arg -Xnorelocate
--no-generate-debug-info最后这几个前面都说过了。
32位的boot.art
out/host/linux-x86/bin/dex2oat
--runtime-arg -Xms64m
--runtime-arg -Xmx64m
--image-classes=frameworks/base/preloaded-classes
--dex-file=out/target/common/obj/JAVA_LIBRARIES/core-libart_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/conscrypt_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/okhttp_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/core-junit_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/bouncycastle_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/ext_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/framework_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/telephony-common_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/voip-common_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/ims-common_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/apache-xml_intermediates/javalib.jar --dex-file=out/target/common/obj/JAVA_LIBRARIES/org.apache.http.legacy.boot_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-common_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-framework_intermediates/javalib.jar
--dex-file=out/target/common/obj/JAVA_LIBRARIES/mediatek-telephony-common_intermediates/javalib.jar
--dex-location=/system/framework/core-libart.jar
--dex-location=/system/framework/conscrypt.jar
--dex-location=/system/framework/okhttp.jar
--dex-location=/system/framework/core-junit.jar
--dex-location=/system/framework/bouncycastle.jar
--dex-location=/system/framework/ext.jar
--dex-location=/system/framework/framework.jar
--dex-location=/system/framework/telephony-common.jar
--dex-location=/system/framework/voip-common.jar
--dex-location=/system/framework/ims-common.jar
--dex-location=/system/framework/apache-xml.jar
--dex-location=/system/framework/org.apache.http.legacy.boot.jar
--dex-location=/system/framework/mediatek-common.jar
--dex-location=/system/framework/mediatek-framework.jar
--dex-location=/system/framework/mediatek-telephony-common.jar上面都是java和dex，所以跟64位没有什么区别。
--oat-symbols=out/target/product/6753_65t_m/symbols/system/framework/arm/boot.oat
--oat-file=out/target/product/6753_65t_m/dex_bootjars/system/framework/arm/boot.oat
--oat-location=/system/framework/arm/boot.oat
--image=out/target/product/6753_65t_m/dex_bootjars/system/framework/arm/boot.art输出文件从arm64目录换到了arm目录
--base=0x70000000基地址没变，反正patchoat的时候也还要改。
--instruction-set=arm
--instruction-set-variant=cortex-a53
--instruction-set-features=default指令集从arm64变成了arm，其它的参数都不变
--android-root=out/target/product/6753_65t_m/system
--include-patch-information
--runtime-arg -Xnorelocate
--no-generate-debug-infodex2oat编译应用的例子
out/host/linux-x86/bin/dex2oat
--runtime-arg -Xms64m
--runtime-arg -Xmx512m这两个值在前面分析Android.oat.mak时已经分析过了，这里验证了我们的分析是正确的。
--boot-image=out/target/product/6753_65t_m/dex_bootjars/system/framework/boot.art这个boot.art就是上一节讲的命令刚刚生成的。
--dex-file=out/target/product/6753_65t_m/obj/APPS/MusicFX_intermediates/oat/arm64/package.odex.input
--dex-location=/system/app/MusicFX/MusicFX.apk输入的dex文件
--oat-file=out/target/product/6753_65t_m/obj/APPS/MusicFX_intermediates/oat/arm64/package.odex输出到odex文件，虽然名字叫odex，但是实际上是个oat。普通的应用就不像上节讲的输出boot.oat和boot.art的时候那样输出那么多了，只有一个odex文件，符号表和image都不用。
--android-root=out/target/product/6753_65t_m/system
--instruction-set=arm64
--instruction-set-variant=cortex-a53
--instruction-set-features=default
--include-patch-information
--runtime-arg -Xnorelocate
--no-generate-debug-info
--abort-on-hard-verifier-error
