手撕编译原理：汇编语言不会编

wget -c http://www.nasm.us/pub/nasm/releasebuilds/2.14.02/nasm-2.14.02.tar.xz
tar -xf nasm-2.14.02.tar.xz
cd nasm-2.14.02
ls
./configure --prefix=/usr && make
sudo make install

$ nasm -v
NASM version 2.14.02 compiled on Jun  1 2020

global main
main:
    mov eax, 5
    ret

SRCS := first.asm
OBJS := $(SRCS:.asm=.o)
TARGET := $(OBJS:.o=)
all: $(TARGET)
$(TARGET): $(OBJS)
        gcc -m32 $< -o $@
%.o: %.asm
        nasm -f elf $< -o $@
.PHONY: all clean
clean:
        -rm -rf $(TARGET) $(OBJS)

$ make
gcc -m32 first.o -o first
/usr/bin/ld: cannot find crt1.o: No such file or directory
/usr/bin/ld: cannot find crti.o: No such file or directory
/usr/bin/ld: cannot find /lib/libgcc_s.so.1
collect2: error: ld returned 1 exit status
make: *** [Makefile:7: first] Error 1

sudo yum install glibc-devel.i686 -y
sudo yum install libgcc.i686 -y

nasm -f elf first.asm -o first.o
gcc -m32 first.o -o first

# ./first ; echo $?
./first
echo $?

global main
main:
        mov eax, 15
        mov ebx, 19
        add eax, ebx
        ret

$ gdb add
(gdb) set disassembly-flavor intel
(gdb) disassemble main
Dump of assembler code for function main:
   0x08048480 <+0>:     mov    eax,0xf
   0x08048485 <+5>:     mov    ebx,0x13
   0x0804848a <+10>:    add    eax,ebx
   0x0804848c <+12>:    ret
   0x0804848d <+13>:    xchg   ax,ax
   0x0804848f <+15>:    nop
End of assembler dump.
(gdb) b *0x08048485# break *0x08048485
(gdb) r # run
(gdb) i r eax # info registers eax
eax            0xf                 15
(gdb) si # stepi Step one instruction exactly.
(gdb) info registers ebx
ebx            0x13                19
...
(gdb) i r # info registers
eax            0x22                34
ecx            0xbddbc2e           199081006
edx            0xffffd514          -10988
ebx            0x13                19
esp            0xffffd4ec          0xffffd4ec
ebp            0x0                 0x0
esi            0xf7fc0000          -134479872
edi            0x0                 0
eip            0x804848c           0x804848c <main+12>
eflags         0x216               [ PF AF IF ]
cs             0x23                35
ss             0x2b                43
ds             0x2b                43
es             0x2b                43
fs             0x0                 0
gs             0x63                99
...
(gdb) c # continue
Continuing.
[Inferior 1 (process 21718) exited with code 042]
(bdb) q