研究一下海信官方发布的MP800H固件，以春节版V049_0121为例。
固件文件名叫：
install.img在Linux系统上用
file命令探测一下文件类型
1 $ file install.img
2 install.img: POSIX tar archive (GNU)
原来是tar文件，用
tar命令显示文件列表
1 $ tar tvf install.img
2 -rwxr-xr-x root/root 143300 2010-01-21 19:30 arial.ttf
3 -rwxr-xr-x root/root 1773344 2010-01-21 19:30 audio_firmware.install.bin
4 -rwxr-xr-x root/root 1773 2010-01-21 19:30 configuration.xml
5 -rwxr-xr-x root/root 43400 2010-01-21 19:30 flash_erase
6 -rwxr-xr-x root/root 1730100 2010-01-21 19:30 install_a
7 -rwxr-xr-x root/root 163948 2010-01-21 19:30 mkfs.jffs2
8 -rwxr-xr-x root/root 56936 2010-01-21 19:30 nandwrite
9 drwxr-xr-x root/root 0 2010-01-21 19:30 package1/
10 -rw-r--r-- root/root 797104 2010-01-21 19:30 package1/bluecore.audio.lzma
11 -rwxr--r-- root/root 10260480 2010-01-21 19:30 package1/squashfs1.img
12 -rw-r--r-- root/root 632911 2010-01-21 19:30 package1/bluecore.video.lzma
13 -rw-r--r-- root/root 988127 2010-01-21 19:30 package1/vmlinux.develop.avhdd.mars.bin.lzma
14 -rw-r--r-- root/root 2064 2010-01-21 19:30 package1/usr.local.etc.tar.bz2
15 -rwxr-xr-x root/root 1623760 2010-01-21 19:30 video_firmware.install.bin
其中有个configuration.xml文件，看一下
1 <?xml version="1.0" encoding="ISO-8859-1" ?>
2 <packageFile>
3 <info>
4 <company>Realtek Semiconductor Corp.</company>
5 <description>This image file contains 2 Mars packages. One is for AVHDD on NOR and the other is for AVHDD on NAND.</description>
6 <version>0.0.1</version>
7 <releaseDate>01/21/10 19:30</releaseDate>
8 <signature>MARS AVHDD on NOR or NAND</signature>
9 </info>
10 <installerAP>
11 <fileName>install_a</fileName>
12 </installerAP>
13 <package>
14 <info>
15 <description>This is Mars AVHDD on NOR</description>
16 <version>N/A</version>
17 </info>
18 <flash>
19 <image type="linuxKernel">
20 <fileName>package1/vmlinux.develop.avhdd.mars.bin.lzma</fileName>
21 <targetAddress>0x80100000</targetAddress>
22 <version>SVN:</version>
23 </image>
24 <image type="audioKernel">
25 <fileName>package1/bluecore.audio.lzma</fileName>
26 <targetAddress>0x81b00000</targetAddress>
27 <version>N/A</version>
28 </image>
29 <image type="videoKernel">
30 <fileName>package1/bluecore.video.lzma</fileName>
31 <targetAddress>0x81d80000</targetAddress>
32 <version>N/A</version>
33 </image>
34 <image type="squash">
35 <fileName>package1/squashfs1.img</fileName>
36 <mountPoint>/</mountPoint>
37 </image>
38 <image type="jffs2">
39 <fileName>package1/usr.local.etc.tar.bz2</fileName>
40 <sizeBytesMin>0x50000</sizeBytesMin>
41 <mountPoint>/usr/local/etc</mountPoint>
42 </image>
43 </flash>
44 </package>
45 </packageFile>
install_a 是固件安装程序
下面3个文件是我们最关心的，自制固件就是通过修改/替换它们来实现的：
1) vmlinux.develop.avhdd.mars.bin.lzma 是Linux内核，用lzma压缩的二进制文件。
2) squashfs1.img是根文件系统，类型为
squashfs，一种压缩的只读文件系统。
3) usr.local.etc.tar.bz2包含一些系统配置文件，其内容将会被复制到可读写的文件系统/usr/local/etc下。
用unsquashfs命令解开squashfs1.img
$ unsquashfs squashfs1.img
解开的文件系统放在squashfs-root目录下，麻雀虽小，五脏具全，目录结构如下（只列出目录名）：
1 $ find squashfs-root -type d
2 squashfs-root
3 squashfs-root/bin
4 squashfs-root/dev
5 squashfs-root/etc
6 squashfs-root/etc/reexec_init
7 squashfs-root/etc/init.d
8 squashfs-root/etc/dvdplayer
9 squashfs-root/etc/dvdplayer/script
10 squashfs-root/lib
11 squashfs-root/lib/modules
12 squashfs-root/lib/modules/2.6.12.6-VENUS
13 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel
14 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs
15 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs/ptp
16 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs/udf
17 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs/vcd
18 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs/ufsd
19 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/fs/isofs
20 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/net
21 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/net/ipv4
22 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers
23 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net
24 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless
25 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek
26 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8187
27 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8187/ieee80211
28 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8187/rtl8187
29 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/11n8709
30 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/11n8709/HAL
31 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/11n8709/HAL/rtl8192u
32 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/11n8709/ieee80211
33 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8191su
34 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8191su/HAL
35 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8191su/HAL/rtl8192u
36 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/net/wireless/realtek/rtl8191su/ieee80211
37 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/usb
38 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/usb/net
39 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/usb/host
40 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/drivers/scsi
41 squashfs-root/lib/modules/2.6.12.6-VENUS/kernel/crypto
42 squashfs-root/mnt
43 squashfs-root/mnt/rd
44 squashfs-root/mnt/hda
45 squashfs-root/mnt/hdb
46 squashfs-root/mnt/hdc
47 squashfs-root/mnt/hdd
48 squashfs-root/tmp
49 squashfs-root/sys
50 squashfs-root/usr
51 squashfs-root/usr/bin
52 squashfs-root/usr/sbin
53 squashfs-root/usr/local
54 squashfs-root/usr/local/bin
55 squashfs-root/usr/local/bin/DVD
56 squashfs-root/usr/local/bin/Resource
57 squashfs-root/usr/local/bin/Resource/bmp
58 squashfs-root/usr/local/bin/Resource/TT_Font
59 squashfs-root/usr/local/bin/Resource/CC_Font
60 squashfs-root/usr/local/bin/Resource/dtv_table
61 squashfs-root/usr/local/etc
62 squashfs-root/usr/local/etc/hdd.old
63 squashfs-root/usr/local/etc/hdd.old/root
64 squashfs-root/usr/local/etc/hdd.old/root/lock
65 squashfs-root/usr/local/etc/hdd.old/root/recovery
66 squashfs-root/usr/local/etc/hdd.old/dvdvr
67 squashfs-root/usr/local/etc/hdd.old/fat32
68 squashfs-root/usr/local/etc/hdd.old/livepause
69 squashfs-root/usr/local/etc/dvdplayer
70 squashfs-root/usr/local/lib
71 squashfs-root/usr/local/sbin
72 squashfs-root/usr/local/firmware
73 squashfs-root/proc
74 squashfs-root/sbin
75 squashfs-root/tmp_orig
76 squashfs-root/tmp_orig/lib
77 squashfs-root/tmp_orig/lib/hotplug
78 squashfs-root/tmp_orig/log
79 squashfs-root/tmp_orig/log/dvdplayer
80 squashfs-root/tmp_orig/www
81 squashfs-root/tmp_orig/www/adm
82 squashfs-root/tmp_orig/www/cgi-bin
83 squashfs-root/tmp_orig/lock
84 squashfs-root/tmp_orig/lock/subsys
85 squashfs-root/tmp_orig/lock/hotplug
86 squashfs-root/tmp_orig/lock/hotplug/mount_tmp
87 squashfs-root/tmp_orig/lock/hotplug/rename_tmp
88 squashfs-root/tmp_orig/lock/hotplug/convert_tmp
89 squashfs-root/tmp_orig/ramfs
90 squashfs-root/tmp_orig/ramfs/labels
91 squashfs-root/tmp_orig/ramfs/volumes
92 squashfs-root/tmp_orig/usbmounts
了解了这些，我们已经具备了自制固件的基本条件了。