Linux2.4.18 ---- 25. File System Construction

Linux2.4.18 ---- 25. File System Construction
1. File System Construction
1. Compilation of busybox
Method: Use the redhat9.0 of the Virtual Machine for compilation.
Version: busybox-1.00 --> make menuconfig --> make install

1. Cong @ msi:/work/OS/rootfs/busybox/busybox-1.00 $ readelf-a./busybox | grep "NEEDED"
   
2. 0x00000001 (NEEDED) Shared library: [libm. so.6] --> therefore, the file system must contain the libm and libcrypt libraries, which are optional.
   
3. 0x00000001 (NEEDED) Shared library: [libcrypt. so.1]
   
4. 0x00000001 (NEEDED) Shared library: [libc. so.6] --> the libc library is required and the most basic library.

You do not need to select [] Build BusyBox as a static binary (no shared libs)

2. kernel Modification

1. L128 in init/main. c
   
2. // Int root_mountflags = MS_RDONLY;
   
3. Int root_mountflags = 0

Remove the read-only attribute of the root file system,
The root_mountflags will set the/dev/hda1 attribute to MS_RDONLY in mount_root --> read_super.

3. files under the etc directory

1. Cong @ msi:/work/OS/rootfs/ext2/etc $ tree
   
2. .
   
3. ├ ── Fstab --> only fstab and rcS are required.
   
4. ── Init. d
   
5. │ ── RcS --> only the cross-section and cross section are required.
   
6. ── Mtab --> this file is created by the mount program and is not in the file system.

Fstab content: Mount proc

1. Cong @ msi:/work/OS/rootfs/ext2/etc $ cat fstab
   
2. Proc/proc defaults 0 0

The content of the rcS, mount all

1. Cong @ msi:/work/OS/rootfs/ext2/etc $ cat init. d/rcS
   
2. #! /Bin/sh
   
3. Mount-

4. Create a script for the root file system
Cong @ msi:/work/OS/rootfs/ext2 $ cat creatext2.sh

1. 
   
2. #! /Bin/sh
   
3. TOPDIR = 'pwd'
   
4. Create_fs ()
   
5. {
   
6. Echo "cong: next create fs"
   
7. # Create filesystem
   
8. Cd/tmp/ext2
   
9. 
   
10. # Create a system directory first
    
11. Sudo mkdir-pv dev/tmp/sys/proc/
    
12. Sudo mknod./dev/tty1 c 4 1
    
13. Sudo mknod./dev/console c 5 1
    
14. # Sudo cp $ TOPDIR/busybox./bin/
    
15. # Sudo cp $ TOPDIR/src/hello./bin/sh
    
16. Sudo cp-Arn $ TOPDIR/lib ./
    
17. Sudo cp-Arn $ TOPDIR/bin ./
    
18. Sudo cp-Arn $ TOPDIR/sbin ./
    
19. Sudo cp-Arn $ TOPDIR/etc ./
    
20. }
    
21. Mount_fs ()
    
22. {
    
23. Echo "cong: next losetup/dev/loop0"
    
24. Sudo losetup/dev/loop0./hdc. img
    
25. #512*2048 = 1048576
    
26. Echo "cong: next losetup/dev/loop1"
    
27. Sudo losetup-o 1048576/dev/loop1/dev/loop0
    
28. Echo "cong: next show losetup all"
    
29. Sudo losetup-
    
30. 
    
31. Echo "cong: next mount"
    
32. Mkdir/tmp/ext2
    
33. Sudo mount-t ext2/dev/loop1/tmp/ext2/
    
34. }
    
35. # Fdisk hdc. img to ext2 83
    
36. Make_fs ()
    
37. {
    
38. #64 M
    
39. Dd if =/dev/zero of =./hdc. img bs = 1 M count = 64
    
40. Fdisk./hdc. img <EOF
    
41. N
    
42. P
    
43. 1
    
44. 2048
    
45. 131071
    
46. T
    
47. 83
    
48. W
    
49. EOF
    
50. Sleep 1
    
51. Fdisk-l./hdc. img
    
52. 
    
53. Echo "cong: next losetup/dev/loop0"
    
54. Sudo losetup/dev/loop0./hdc. img
    
55. #512*2048 = 1048576
    
56. Echo "cong: next losetup/dev/loop1"
    
57. Sudo losetup-o 1048576/dev/loop1/dev/loop0
    
58. Echo "cong: next show losetup all"
    
59. Sudo losetup-
    
60. 
    
61. Echo "cong: next mkfs ext2/dev/loop1"
    
62. Sudo mkfs. ext2/dev/loop1
    
63. 
    
64. Echo "cong: next mount"
    
65. Mkdir/tmp/ext2
    
66. Sudo mount-t ext2/dev/loop1/tmp/ext2/
    
67. Create_fs
    
68. }
    
69. Umount_fs ()
    
70. {
    
71. Sudo umount/tmp/ext2
    
72. Sudo losetup-d/dev/loop0
    
73. Sudo losetup-d/dev/loop1
    
74. Sudo losetup-
    
75. }
    
76. 
    
77. Clean_fs ()
    
78. {
    
79. Echo "cong: next umount/tmp/ext2"
    
80. Sudo umount/tmp/ext2
    
81. Echo "cong: next rm-rf/tmp/ext2"
    
82. Sudo rm-rf/tmp/ext2
    
83. Echo "cong: next losetup-d"
    
84. Sudo losetup-d/dev/loop0
    
85. Sudo losetup-d/dev/loop1
    
86. Echo "cong: next show losetup"
    
87. Sudo losetup-
    
88. Echo "cong: next rm-rf./hdc. img"
    
89. Rm-rf./hdc. img
    
90. }
    
91. 
    
92. Case "$1" in
    
93. Fs)
    
94. Make_fs
    
95. ;;
    
96. Clean)
    
97. Clean_fs
    
98. ;;
    
99. Mount)
    
100. Mount_fs
     
101. ;;
     
102. Umount)
     
103. Umount_fs
     
104. ;;
     
105. *)
     
106. Make_fs
     
107. ;;
     
108. Esac

5. Used

1. Cong @ msi:/work/OS/rootfs/ext2 $ tree
   
2. .
   
3. ── Bin --> copies the bin directory of the root file system.
   
4. │ ── Busybox
   
5. │ ── Busybox_0.60.5
   
6. │ ── Cat-> busybox
   
7. │ ── Cp-> busybox
   
8. │ ── Df-> busybox
   
9. │ ── Dmesg-> busybox
   
10. │ ── Echo-> busybox
    
11. │ ├ ── Grep-> busybox
    
12. │ ── Hostname-> busybox
    
13. │ ── Ln-> busybox
    
14. │ ├ ── Ls-> busybox
    
15. │ ── Mkdir-> busybox
    
16. │ ── Mknod-> busybox
    
17. │ ── Mount-> busybox
    
18. │ ── Mv-> busybox
    
19. │ ── Netstat-> busybox
    
20. │ ├ ── Ping-> busybox
    
21. │ ── Ps-> busybox
    
22. │ ── Pwd-> busybox
    
23. │ ── Rm-> busybox
    
24. │ ├ ── Sh-> busybox
    
25. │ ── Sync-> busybox
    
26. │ ── Touch-> busybox
    
27. │ ── Umount-> busybox
    
28. │ ── Vi-> busybox
    
29. ── Creatext2.sh --> Create a script for the root file system
30. ── Etc--> Is copiedEtc of the root file systemDirectory
    
31. │ ── Fstab
    
32. │ ── Init. d
    
33. │ ── RcS
    
34. │ ── Mtab
    
35. ── Lib--> Is copiedLib of the root file systemDirectory
    
36. │ ── Ld-linux.so.2 // Interpreter
    
37. │ ├ ── Libc-2.3.2.so // libc library, this is the most basic
    
38. │ ├ ── Libcrypt-2.3.2.so // The Rest Of The libcrypt and libm library single run helloworld is not needed
    
39. │ ├ ── Libcrypt. so.1-> libcrypt-2.3.2.so
    
40. │ ├ ── Libc. so.6-> libc-2.3.2.so // but here the busybox is used, it is added
    
41. │ ── Libm-2.3.2.so.
    
42. │ └ ── Libm. so.6-> libm-2.3.2.so
    
43. ── Makefile
    
44. ── Sbin--> Is copiedSbin of the root file systemDirectory
    
45. │ ├ ── Ifconfig-> ../bin/busybox
    
46. │ ── Init-> ../bin/busybox
    
47. │ ── Insmod-> ../bin/busybox
    
48. │ ── Lsmod-> ../bin/busybox
    
49. │ ── Modprobe-> ../bin/busybox
    
50. │ ── Rmmod-> ../bin/busybox
    
51. ── Src--> Code of some test programs
    
52. ──
    
53. │ ── Hello. s
    
54. │ ── Makefile
    
55. ── Hello. c
    
56. ── Makefile
    
57. ── Mycompile. sh
    
58. ── Nasm
    
59. ── Hello
    
60. ── Hello. o
    
61. ── Hello. s
    
62. ── Hello. s_nasm
    
63. ── Init. c_hello
    
64. ── Makefile
    
65. 
    
66. 8 directories, 54 files

5.1 package the files used
Ext2.rar(change the name to ext2.tar.gz after downloading)