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Update program_startup.md

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0xAX 2016-09-11 19:55:15 +06:00 committed by GitHub
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Misc/program_startup.md
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@ -157,7 +157,7 @@ $ gcc -v -ggdb program.c -o sum
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/usr/libexec/gcc/x86_64-redhat-linux/6.1.1/cc1 -quiet -v test.c -quiet -dumpbase test.c -mtune=generic -march=x86-64 -auxbase test -ggdb -version -o /tmp/ccvUWZkF.s
/usr/libexec/gcc/x86_64-redhat-linux/6.1.1/cc1 -quiet -v program.c -quiet -dumpbase program.c -mtune=generic -march=x86-64 -auxbase test -ggdb -version -o /tmp/ccvUWZkF.s
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@ -211,7 +211,7 @@ collect2: error: ld returned 1 exit status
Besides other errors, we also see that `_start` symbol is undefined. So now we are sure that the `_start` function comes from standard library. But even if we will link it with standard library, it will not be compiled successfully anyway:
```
~$ gcc -nostdlib -lc -ggdb test.c -o program
~$ gcc -nostdlib -lc -ggdb program.c -o program
/usr/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400350
```
@ -332,7 +332,7 @@ After stack aligning we push address of the stack, addresses of contstructor and
Before we will look at the `__libc_start_main` function let's add the `/lib64/crt1.o` and try to compile our program again:
```
$ gcc -nostdlib /lib64/crt1.o -lc -ggdb test.c -o program
$ gcc -nostdlib /lib64/crt1.o -lc -ggdb program.c -o program
/lib64/crt1.o: In function `_start':
(.text+0x12): undefined reference to `__libc_csu_fini'
/lib64/crt1.o: In function `_start':