三个问题

了解Hello World程序的执行过程有什么用?

1、对开发其他应用程序，有非常好的借鉴意义。

2、对程序的报错有清晰的了解，从而针对性地解决问题。

裸机开发中的HelloWorld程序是怎么执行的?

Linux系统下的Hello World程序是怎么执行的?

四个案例

gcc预处理c文件

/usr/lib/gcc/x86_64-linux-gnu/7/cc1 -E -quiet -v -imultiarch x86_64-linux-gnu hello.c -o hello.i -mtune=generic -march=x86-64 -fstack-protector-strong -Wformat -Wformat-security

gcc编译c文件

/usr/lib/gcc/x86_64-linux-gnu/7/cc1 -fpreprocessed hello.i -quiet -dumpbase hello.i -mtune=generic -march=x86-64 -auxbase-strip hello.s -version -o hello.s -fstack-protector-strong -Wformat -Wformat-security

gcc编译汇编

as -v —64 -o hello.o hello.s

gcc链接可重定位文件

ld连接器

collect2封装了ld连接器

/usr/lib/gcc/x86_64-linux-gnu/7/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/7/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper -plugin-opt=-fresolution=/tmp/ccUh28GP.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s —build-id —eh-frame-hdr -m elf_x86_64 —hash-style=gnu —as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie -z now -z relro -o hello /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o -L/usr/lib/gcc/x86_64-linux-gnu/7 -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/7/../../.. hello.o -lgcc —push-state —as-needed -lgcc_s —pop-state -lc -lgcc —push-state —as-needed -lgcc_s —pop-state /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o

静态链接

/usr/lib/gcc/x86_64-linux-gnu/7/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/7/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper -plugin-opt=-fresolution=/tmp/ccmFACnG.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lc —build-id -m elf_x86_64 —hash-style=gnu —as-needed -static -z relro -o hello_static /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginT.o -L/usr/lib/gcc/x86_64-linux-gnu/7 -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/7/../../.. hello.o —start-group -lgcc -lgcc_eh -lc —end-group /usr/lib/gcc/x86_64-linux-gnu/7/crtend.o /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o