I would not dare to upload a firmware built from scratch, but what about only slightly modified one?
For me, it would suffice to just add a call to some script on the flash drive that would be launched at boot. From there I'd be able to do all I need (ATM).
The WL-600g GPL Makefile contains the following default sequence of commands in its
buildimage section:
./buildFS
$(HOSTTOOLS_DIR)/mksquashfs $(TARGET_FS) $(PROFILE_DIR)/rootfs.img -noappend -be -lzma -no-fragments -noI
$(OBJCOPY) -O binary vmlinux vmlinux.bin
$(HOSTTOOLS_DIR)/cmplzma -k -2 vmlinux vmlinux.bin vmlinux.lz;\
$(HOSTTOOLS_DIR)/bcmImageBuilder --output $(CFE_FS_KERNEL_IMAGE_NAME) --chip $(BRCM_CHIP) --board $(BRCM_BOARD_ID) \
--productname $(CUSTOMER_PRODUCT_NAME) --blocksize $(BRCM_FLASHBLK_SIZE) --cfefile $(CFE_FILE) --rootfsfile rootfs.img --kernelfile vmlinux.lz --include-cfe;
Let's keep hoping that WL-600g is the same as AM-200g, try to reverse the process, do the modifications and put together again.
bcmImageBuilder should just put together the filesystem file, kernel, cfe file (st like bios - see
OpenWRT - Everything you need to know about broadcom hardware (Part 1)) and some checksums. There is a utility done by OpenWRT people that should be a replacement of
bcmImageBuilder.
Here. From there I learned the structure of the header, let's repeat it here for the sake of completeness:
The header takes the first 256 bytes
/* Image component */
struct imagecomp {
uint8_t address[12]; /* Address of this component as ASCII */
uint8_t len[10]; /* Length of this component as ASCII */
};
/* Image tag */
struct imagetag {
uint8_t tagver[4]; /* 0 - 3: Version of the tag as ASCII (2) */
uint8_t sig1[20]; /* 4 - 23: BCM_MAGIC_1 */
uint8_t sig2[14]; /* 24 - 37: BCM_MAGIC_2 */
uint8_t chipid[6]; /* 38 - 43: Chip id as ASCII (6345) */
uint8_t boardid[16]; /* 44 - 59: Board id as ASCII (96345GW2, etc...) */
uint8_t bigendian[2]; /* 60 - 61: "1" for big endian, "0" for little endian */
uint8_t imagelen[10]; /* 62 - 71: The length of all data that follows */
struct imagecomp cfe; /* 72 - 93: The offset and length of CFE */
struct imagecomp rootfs; /* 94 - 115: The offset and length of the root file system */
struct imagecomp kernel; /* 116 - 137: The offset and length of the kernel */
uint8_t dualimage[2]; /* 138 - 139: use "0" here */
uint8_t inactive[2]; /* 140 - 141: use "0" here */
uint8_t reserved1[74]; /* 142 - 215: reserved */
uint32_t imagecrc; /* 216 - 219: crc of the images (net byte order) */
uint8_t reserved2[16]; /* 220 - 235: reserved */
uint32_t headercrc; /* 236 - 239: crc starting from sig1 until headercrc (net byte order) */
uint8_t reserved3[16]; /* 240 - 255: reserved */
};
Let's decompose it for the
firmware from Joyce:
tagver="36 00 00 00" = "6..."
sig1="42 72 6f 61 64 63 6f 6d 20 43 6f 72 70 6f 72 61 74 69 6f 00" = "Broadcom Corporatio."
sig2="76 65 72 2e 20 32 2e 30 00 00 00 00 00 00" = "ver. 2.0......"
chipid="36 33 34 38 00 00" = "6348.."
boardid="39 36 33 34 38 47 57 2d 31 31 00 00 00 00 00 00" = "96348GW-11......"
bigendian="31 00" = "1"
imagelen="33 38 32 32 33 35 36 00 00 00" = "3822356..." #indeed 3822356 + 256 = 3822612 (the size of the firmware file)
cfe="33 32 31 37 30 33 31 31 36 38 00 00 36 32 31 37 32 00 00 00 00 00" = "32170311..62172....." # this starts to be tricky ...
## 62172 is clearly the cfe size, but the cfe itself is slightly different from the files provided in the WL-600g GPL package.
rootfs="33 32 68 31 37 30 39 36 39 36 30 00 00 33 31 33 37 35 33 36 00 00 00" = "3217096960..3137536..." #fs size = 3137536
kernel="33 32 32 30 32 33 34 34 39 36 00 00 36 32 32 36 34 38 00 00 00 00" = "3220234496..622648...." # kernel size = 622648
## 3137536+622648+62172+256=3822612 - all fits so far!
dualimage="00 00"
inactive="00 00"
reserved="00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00"
imagecrc="c9 ea a8 50"
reserved2=""
The reserved2 part is different from WL-600g - after some experimentation, I found out that the first four bytes are CRC of the fs image and the second four bytes are CRC of the kernel, but was not able to figure out the CRC algorithm.
to extract cfe:
dd bs=1 if=JOYCE_IAD_U2_B_306063520_cfe_fs_kernel of=cfe skip=256 count=62172
to extract fs:
dd bs=1 if=JOYCE_IAD_U2_B_306063520_cfe_fs_kernel of=fs skip=62428 count=3137536
to extract kernel:
dd bs=1 if=JOYCE_IAD_U2_B_306063520_cfe_fs_kernel of=kernel skip=3199964 count=622648
By calling the Asus' bcmImageBuilder command on the extracted files, I got a firmware identical (verified with md5sum) to the original:
../../Dokumenty/GPL_AM604G_ForRussia/GENERIC_6348_WLAN_A34_3-06-02-01/hostTools/bcmImageBuilder --output bcmimage --chip 6348 --board 96348GW-11 --blocksize 64 --cfefile cfe --rootfsfile fs --kernelfile kernel --include-cfe
So, let's proceed further...
$ file fs
fs: Squashfs filesystem, big endian, version 2.0, 3136535 bytes, 423 inodes, blocksize: 65536 bytes, created: Mon May 28 08:35:59 2007
the file command confirms the fs file is indeed a squashfs image. Let's extract it:
$ unsquashfs -s fs
Reading a different endian SQUASHFS filesystem on fs
Can't find a SQUASHFS superblock on fs
This is already
reported in Ubuntu, I
reported it to the Mandriva guys as well.
The hand-compiled squashfs 3.3 seemed to work just fine, but it was not able to deal with the Broadcom specific lzma compression. I tried to mount the fs file on the router, but unfortunately
mount was not compiled with support for mounting loop devices
# mount -o ro -o loop /var/usb/usb_2/fs /var/usb/a
mount: Mounting /var/usb/usb_2/fs on /var/usb/a failed: Block device required
After some retries I found out about the excellent
OpenBox4 people hacking another Broadcom based ADSL router. They developed
nb4-unsquash - a tool to extract the content of Broadcom-lzma-compressed squashfs.
But I still did not trust it entirely. I found out I can mount the internal flash and that's enough for me.
First I made a backup of the original fs:
# mkdir /var/usb/a
# mount -o ro /dev/mtdblock0 /var/usb/a
# /var/usb/usb_1/bin/tar cvf /var/usb/usb_2/firmwarefs.tar /var/usb/a/
Copied the filesystem to my PC:
on-my-PC $ mkdir /tmp/fs
on-my-PC $ netcat -l -p 9000 | dd of=/tmp/fs/fs.tar
on-router# /var/usb/usb_1/bin/dd if=/var/usb/usb_2/firmwarefs.tar |/var/usb/usb_1/bin/mipsel-linux-netcat 192.168.1.64 9000
Unpacked (as root because the contents are special files):
$ su
# cd /tmp/fs
# tar xvf fs.tar
Before doing any modifications I tried recreating the squashfs image:
# /home/hajma/Dokumenty/GPL_AM604G_ForRussia/GENERIC_6348_WLAN_A34_3-06-02-01/hostTools/mksquashfs /tmp/fs/var/usb/a rootfs.img -noappend -be -lzma -no-fragments -noI
and verified with the nb4-unsquash that it looks similar to the original one:
# nb4-unsquash -d new rootfs.img
# nb4-unsquash -d old /tmp/joycefs
# ls -laR old/ > /tmp/oldfslist
# ls -laR new/ > /tmp/newfslist
# kdiff3 /tmp/oldfslist /tmp/newfslist
I saw that all except some modification times was identical, so I put the recreated fs together with the old kernel and cfe:
# /home/hajma/Dokumenty/GPL_AM604G_ForRussia/GENERIC_6348_WLAN_A34_3-06-02-01/hostTools/bcmImageBuilder --output bcmimage --chip 6348 --board 96348GW-11 --blocksize 64 --cfefile cfe --rootfsfile rootfs.img --kernelfile kernel --include-cfe
Then I took a deep breath and flashed the router with the recreated firmware ... ... ... ... ... ...
And it worked!
Unfortunately it was not possible to simply find a place in the boot sequence where everything is already done and flash is mounted. The
/etc/profile, launched by the line
::respawn:-/bin/sh of
/etc/inittab, calls
/bin/cfm, which takes care of all the ADSL settings and mounting the flash - but it stays loaded and the script does not go on. So after several retries I found a solution - added another line to the
/etc/inittab:
$ diff -u inittab.old inittab
--- inittab.old 2008-07-03 00:31:44.000000000 +0200
+++ inittab 2008-07-03 00:31:52.000000000 +0200
@@ -1,5 +1,6 @@
+::respawn:-/bin/myscript.sh
tty2::askfirst:-/bin/sh
that will launch a script that waits until the flash drive is mounted and then passes the command to script residing on the flash:
$ cat bin/myscript.sh
#!/bin/sh
while [ "`echo /var/usb/usb_*`" = "/var/usb/usb_*" ]; do
ping 127.0.0.1 # the shell does not have the sleep builtin, hence using ping as a substitute
done
ping -c 20 127.0.0.1 # wait 20 seconds after the usb is mounted just to be sure load is not too high
/bin/sh /var/usb/usb_2/myscript.sh > /var/usb/usb_2/myscript.log 2>&1
Then I created the new image:
# /home/hajma/Dokumenty/GPL_AM604G_ForRussia/GENERIC_6348_WLAN_A34_3-06-02-01/hostTools/mksquashfs /tmp/fs/var/usb/a rootfs.img -noappend -be -lzma -no-fragments -noI
Combined with the rest of the lot:
# /home/hajma/Dokumenty/GPL_AM604G_ForRussia/GENERIC_6348_WLAN_A34_3-06-02-01/hostTools/bcmImageBuilder --output bcmimage --chip 6348 --board 96348GW-11 --blocksize 64 --cfefile cfe --rootfsfile rootfs.img --kernelfile kernel --include-cfe
and flashed. Works like a charm. I put the firmware to the
OpenWRT page on AM-200g.
direct link
In the next part I'll try to fix the dhcp.
FYI, this is the content of the
/var/usb/usb_2/myscript.sh file, launching the jabber daemon:
#!/bin/sh
/bin/iptables -I INPUT -p tcp -i ppp_8_48_1 --dport 5222 -m state --state NEW -j ACCEPT
/bin/iptables -I INPUT -p tcp -i ppp_8_48_1 --dport 5223 -m state --state NEW -j ACCEPT
/bin/iptables -I INPUT -p tcp -i ppp_8_48_1 --dport 5269 -m state --state NEW -j ACCEPT
/var/usb/usb_1/bin/jabberd -c /var/usb/usb_2/jabberd/jabber.xml
FYI, the steps to cross-compile netcat and coreutils (for the tar and dd commands):
$ wget ftp://heanet.dl.sourceforge.net/n/ne/netcat/netcat-0.7.1.tar.bz2
$ tar xvf netcat-0.7.1.tar.bz2
$ cd netcat-0.7.1
$ ./configure --build=i686-pc-linux-gnu --host=mipsel-linux --target=mipsel-linux --prefix=/var/usb/usb_1
$ make
$ make install
$ cd ..
$ wget http://ftp.gnu.org/gnu/coreutils/coreutils-6.9.tar.bz2
$ tar xvf coreutils-6.9.tar.bz2
$ cd coreutils-6.9
$ ./configure --build=i686-pc-linux-gnu --host=mipsel-linux --target=mipsel-linux --prefix=/var/usb/usb_1
$ make
$ make install
Customizing Asus AM200g - IV. jabberd configuration
Customizing Asus AM200g - III. jabberd and vim
Customizing Asus AM200g - II. Preparing the environment
Customizing Asus AM200g - I. PREPARATION
