GM MDI serial number: How to get new serial

Here are some great tips and guides of GM MDI clone serial number update from HMM Forum，Collected by OBDexpress.co.uk

The GM MDI serial number is in the 16mb on board flash memory – the intel chip on the computer sub-board.

You can get u-boot access by making up a serial cable. Signals are available on the 8 pin mini din on the outside of the MDI case. pin 1 goes to PC TX (MDI

RX), pin 2 goes to PC RX (MDI TX). Pin 3 goes to ground. Then when you boot:

Quote:U-Boot 1.1.4 (Dec 21 2007 – 12:11:55) ETAS VCI (r13006)

U-Boot code: A3F00000 -> A3F218F0 BSS: -> A3F27524

RAM Configuration: TRITON 270 II

Bank #0: a0000000 64 MB

Bank #1: a4000000 64 MB

HW Configuration: (0x207) MDI VCI with SMSC9116

Found P30 Flash, unlocking all blocks: 130

Flash: 16 MB

In: serial

Out: serial

Err: serial

Hit any key to stop autoboot: 0

$ help

? – alias for ‘help’

askenv – get environment variables from stdin

autoscr – run script from memory

base – print or set address offset

bdinfo – print Board Info structure

boot – boot default, i.e., run ‘bootcmd’

bootd – boot default, i.e., run ‘bootcmd’

bootm – boot application image from memory

bootp – boot image via network using BootP/TFTP protocol

cmp – memory compare

coninfo – print console devices and information

cp – memory copy

crc32 – checksum calculation

dhcp – invoke DHCP client to obtain IP/boot params

echo – echo args to console

erase – erase FLASH memory

exit – exit script

flinfo – print FLASH memory information

flock – physical lock of Strataflash

funlock – physical unlock of Strataflash

go – start application at address ‘addr’

help – print online help

iminfo – print header information for application image

imls – list all images found in flash

increnv – increment environment variables

itest – return true/false on integer compare

loadb – load binary file over serial line (kermit mode)

loads – load S-Record file over serial line

loop – infinite loop on address range

macaddr – display or store MAC address in Strataflash

mapadd – add a memory map item

mapdel – delete a memory map item

mapinfo – display the memory map information

md – memory display

mm – memory modify (auto-incrementing)

mmcinfo – get info on mmc(sd) card

mtest – simple RAM test

mw – memory write (fill)

nfs – boot image via network using NFS protocol

nm – memory modify (constant address)

ping – send ICMP ECHO_REQUEST to network host

pinit – PCMCIA sub-system

printenv- print environment variables

protect – enable or disable FLASH write protection

rarpboot- boot image via network using RARP/TFTP protocol

reset – Perform RESET of the CPU

run – run commands in an environment variable

saveenv – save environment variables to persistent storage

serialnum – display or store serial number in Strataflash

setenv – set environment variables

sleep – delay execution for some time

test – minimal test like /bin/sh

tftpboot- boot image via network using TFTP protocol

version – print monitor version

The problem is the serial number and MAC flash partitions are misaligned from the flash erase block boundaries, which forces them to mount read only. Because of this the update commands don’t work

Code:

$ serialnum Serial number: 1220-22129579 $ serialnum 1220-12345678 Error: start address not on sector boundary Failed to read same serial number back from Strataflash

I think that if we mapped a memory partition at 0x00FE0000 with size 0x00020000 then we would be able to erase that partition and load a new one via ethernet / tftp. This 128k block would cover both the serial and mac paritions. Both these partitions have checksums which would need to be figured out and calculated.

What you have been editing is the equivalent of the MDI registry. Once the

serial and mac are changed in flash then a re-flash of the device should put

the new numbers in the registry and they should persist over device firmware

updates. I expect duplicate mac addresses are as relevant as the serial number

duplicates on your lan.

Quote:$ mapinfo Name Location Size Type Source Guard —- ——– —- —- —— —– boot 0x00000000 0x00040000 Flash bootargs Off bootvars 0x00040000 0x00020000 Flash bootargs Off linux1 0x00060000 0x00180000 Flash bootargs Off initrd1 0x001e0000 0x00600000 Flash bootargs Off linux2 0x007e0000 0x00180000 Flash bootargs Off initrd2 0x00960000 0x00600000 Flash bootargs Off linuxvars1 0x00f60000 0x00020000 Flash bootargs Off linuxvars2 0x00f80000 0x00020000 Flash bootargs Off serialnum 0x00ff0000 0x00008000 Flash bootargs Off macaddress 0x00ff8000 0x00008000 Flash bootargs Off zImage 0xa0008000 0x00200000 DRAM Initial Off scratch 0xa2000000 0x00a00000 DRAM Initial Off script 0xa2a00000 0x00100000 DRAM Initial Off Stack 0xa3e9ff80 0x00020000 DRAM System On GD 0xa3ebff80 0x00000080 DRAM System On Heap 0xa3ec0000 0x00040000 DRAM System On Text 0xa3f00000 0x000218f0 DRAM System On BSS 0xa3f218f0 0x00005c34 DRAM System On

The sdcard is just the /usr/local/ portion of the firmware. The rest is in the 16mb flash.

Be careful, its super easy to brick your MDI Interface with these tools.

Figured it out. Mount the sdcard parition 1 under linux, and rename telnetd.sh-disabled to telnet.sh in /bin. While there I also edited the init script and added this near the start to make the prompt nicer:

Quote:export PS1='[\u@mdi \W]\$ ‘

Access u-boot (38400 baud, see previous post), and at the prompt type:

Quote:askenv setbootargsprimary

Please enter ‘setbootargsprimary’:run normalargs addinit addconsole addeth

addprimary;setenv bootargs ${bootargs}

mtdparts=flash0:256k(boot),128k(bootvars),1536k(linux1),6144k(initrd1),1536k(linux2),6144k(initrd2),128k(linuxvars1),128k(linuxvars2),32k@16320k(serialnum),32k(macaddress),128k@16256k(id);

boot

The MDI will boot and start a telnet server on its IP and have a new flash partition configured as /dev/mtd10 called ‘id’. This will align with the erase block so can be updated. Check in /var/log/messages for the presence of ‘id’ without it being forced readonly.

Telnet in and rip a copy of mtd10 with dd, and send it to an ftp server you

have setup on your lan.

Quote:[root@mdi ~]# cd /tmp [root@mdi tmp]# dd if=/dev/mtd10 of=mtd10.img 256+0 records in 256+0 records out [root@mdi tmp]# ls -l mtd10.img -rw-r–r– 1 root root 131072 Jan 1 00:07 mtd10.img [root@mdi tmp]# ftpput -u <user> -p <pass> <ip> mtd10.img mtd10.img

Now load up mtd10.img on your pc in HxD or Hexworkshop. The serial is at 0x10000 with a crc32 checksum of 0x10000->0x17FFB at 17FFC (LSB).

MAC is at 18000 with a crc32 checksum 0x18000->0x1FFFB at 1FFFC.

Update both (just change the last couple of numbers), and use the calculate

checksum feature of the hexeditor to calculate crc32 the sums of of the ranges

and save the new sums in the bin (remember to enter them in LSB format).

Now pull the files back to the mdi, and update flash:

Quote:[root@mdi ~]# cd /tmp [root@mdi tmp]# ftpget -u <user> -p <pass> <ip> mtd10-new.img mtd10-new.img [root@mdi tmp]# cd /usr/local/mtd/ [root@mdi mtd]# ./flash_unlock /dev/mtd10 [root@mdi mtd]# ./flash_erase /dev/mtd10 Erase Total 1 Units Performing Flash Erase of length 131072 at offset 0x0 done [root@mdi mtd]# ./flashcp /tmp/mtd10-new.img /dev/mtd10 [root@mdi mtd]# dd if=/dev/mtd10 of=/tmp/mtd10-readback.img 256+0 records in 256+0 records out [root@mdi mtd]# md5sum /tmp/mtd10-new.img /tmp/mtd10-readback.img 1a1f4fb7db878218c558b45c0db50c9f /tmp/mtd10-new.img 1a1f4fb7db878218c558b45c0db50c9f /tmp/mtd10-readback.img

Now reboot the MDI, and hold down the power button so it goes in to recovery mode. Use MDI manager to recover the device. Once completed it’ll have the new serial and mac.

I expect that the cloners will find this thread and soon they won’t all have

the same serial anymore. But if you already have one then you can do this

yourself, so long as your careful and make sure everything is going to plan and

makes sense to you as you go.

(Many many many thanks to gmtools at https://mhhauto.com/Thread-GM-MDI-serial-number?)

Source:http://blog.obdexpress.co.uk/2018/12/06/how-to-update-cloned-gm-mdi-serial-number/