Test the-ttext parameter in the LD command

File sramboot. s

# Include "regdef. H"

. Text

. Globl main

Main:

. Set noreorder

. Set noat

La AT, Value

LW A0, 0 ()

LW A1, 4 ()

Jal my_add

Add A2, A0, A1

SW A2, 8 ()

 

File # include "regdef. H"

. Text

. Globl my_add, Value

My_add:

. Set noreorder

Add A0, A0, 3

J Ra

Add A1, A1, 4

. Data

Value:. Word 10, 20, 0

 

Makefile

Cc = mipsel-Linux-gcc

As = mipsel-Linux-

LD = mipsel-Linux-LD

Objdump = mipsel-Linux-objdump

Objcopy = mipsel-Linux-objcopy

Textbase =

Ldflags = $ (textbase)-t my. LD

Test. Bin: test.exe

$ (Objcopy)-O binary test.exe test. Bin

Test.exe: Call. O sramboot. o

$ (LD) Call. O sramboot. o $ (ldflags)-O test.exe

$ (Objdump)-D test.exe> test. Dump

RM *. s

Sramboot. O: sramboot. s

$ (CC)-E sramboot. S-O sramboot. s

$ (AS) sramboot. S-O sramboot. o

Call. O: Call. s

$ (CC)-E call. S-O call. s

$ (AS) Call. S-O call. o

Clean:

RM *. O *. EXE *. Bin *. Dump

 

My. LD File

Output_format ("elf32-tradlittlemips", "elf32-tradbigmips", "elf32-tradlittlemips ")

Output_arch (MIPs)

 

Sections

{

. Init:

{

Sramboot. o

}

. Text:

{

* (. Text)

}

. Data:

{

* (. Data)

}

. BSS:

{

* (. BSS)

}

}

 

Test. Sh File

#! /Bin/sh

Mipsel-Linux-objdump-D-m mips-B Binary-el-m no-aliases-z test. Bin> my. Dump

Production depends on the native machine code and can run test. Sh

Only test. Dump

Test 1:

No ttext. = 0 is specified

Test.exe: File Format elf32-tradlittlemips

Disassembly of section. init:

00000000 <main>:

0: 3c010000 lui at, 0x0

4: 24210050 addiu at, at, 80

8: 8c240000 LW A0, 0 ()

C: 8c250004 LW A1, 4 ()

10: 0c000008 Jal 20 <my_add>

14: 00000000 NOP

18: 00853020 add A2, A0, A1

1c: ac260008 SW A2, 8 ()

Disassembly of section. Text:

00000020 <my_add>:

20: 20840003 addi A0, A0, 3

24: 03e00008 Jr Ra

28: 20a50004 addi A1, A1, 4

2c: 00000000 NOP

Disassembly of section. reginfo:

 

00000030 <. reginfo>:

30: 80000030 LB zero, 48 (zero)

...

Disassembly of section. Data:

 

00000050 <value>:

50: 0000000a 0xa

54: 00000014 0x14

Test 2:

-Ttext = 0x50. = 0

Test.exe: File Format elf32-tradlittlemips

Disassembly of section. Text:

00000050 <my_add>:

50: 20840003 addi A0, A0, 3

54: 03e00008 Jr Ra

58: 20a50004 addi A1, A1, 4

5C: 00000000 NOP

Disassembly of section. reginfo:

 

00000060 <. reginfo>:

60: 80000030 LB zero, 48 (zero)

...

Disassembly of section. init:

 

00000000 <main>:

0: 3c010000 lui at, 0x0

4: 24210080 addiu at, at, 128

8: 8c240000 LW A0, 0 ()

C: 8c250004 LW A1, 4 ()

10: 0c000014 Jal 50 <my_add>

14: 00000000 NOP

18: 00853020 add A2, A0, A1

1c: ac260008 SW A2, 8 ()

Disassembly of section. Data:

 

00000080 <value>:

80: 0000000a 0xa

84: 00000014 0x14

 

Test 3:

-Ttext = 0x50. = 0x80000000 (added before. Text output Section)

The result indicates that ttext has a high priority and affects the virtual address of the. Data Output section.

Test.exe: File Format elf32-tradlittlemips

 

Disassembly of section. Text:

 

00000050 <my_add>:

50: 20840003 addi A0, A0, 3

54: 03e00008 Jr Ra

58: 20a50004 addi A1, A1, 4

5C: 00000000 NOP

Disassembly of section. reginfo:

 

00000060 <. reginfo>:

60: 80000030 LB zero, 48 (zero)

...

Disassembly of section. init:

 

00000000 <main>:

0: 3c010000 lui at, 0x0

4: 24210080 addiu at, at, 128

8: 8c240000 LW A0, 0 ()

C: 8c250004 LW A1, 4 ()

10: 0c000014 Jal 50 <my_add>

14: 00000000 NOP

18: 00853020 add A2, A0, A1

1c: ac260008 SW A2, 8 ()

Disassembly of section. Data:

 

00000080 <value>:

80: 0000000a 0xa

84: 00000014 0x14

...,

Through the above tests, we can see that-ttext (-tdata-tbss) has a higher priority than. Counter,

Because we didn't specify LMA, LMA = VMA, so when we specify-ttext, the native machine code is filled with a large amount of invalid data, occupying storage space,

By specifying LMA, we can effectively reduce the occupied storage space.