Cellular Modem Information » Qualcomm Linux Modems by Quectel & Co

h1. EC20/EC25 Delta Firmware over the air (DFOTA) upgrades

An example of the DFOTA file is here: http://dfota.quectel-service.com:8088/Dfiles/EC20/EC20EQAR02A05V03-R02A09V02.zip. EC25 seems to use the stock "recovery"/"applypatch".

h2. Mechanism

It is based on the recovery.git of Android. For the EC20 the delta format (and RSA signing) has been replaced by the usage of

RedBend FOTA. The RedBend FOTA is used by other Qualcomm customers too and is also used on the UC20. For the EC25 it

seems that the stock Android/LinuxFoundation @recovery@ is used.

The general approach is:

* APN is configured for the Linux system

* AT+QFOTADL is handled by atfwd_daemon and starts @wget@ to write to @update.zip@

* @"IP_START_UPDATE" > /cache/fota/ipth_config_dfs.txt@

* Reboot into the recovery image

* recovery will apply the update.

h2. Start delta upgrade

<pre>

AT+QICSGP=1,1,"APN_NAME_HERE","","",1

AT+QFOTADL="http://dfota.quectel-service.com:8088/Dfiles/EC20/EC20EQAR02A05V03-R02A09V02.zip"

</pre>

It will start an internal connection manager to terminate data on the Linux module and then run wget to store the file to

"update.zip". If it worked a reboot into the recovery system will be made.

h2. Recovery image

The @/usr/bin/recovery@ of the recovery image will be started on boot and checks for a @update.zip@ and

the instructions in @ipth_config_dfs.txt@ and then apply the updates. Maintain some counters for how often

an upgrade was attempted and reboot into the main image.

h2. Delta format

Delta updates can update images (e.g. bootloader, kernel) and files on a mounted filesystem. The update.zip

contains one file per image/filesystem to update. The general format is the same for both images and filesystems

and the semantic comes from the partition table supplied by the recovery application to the RedBend component.

The delta update consists out of several nested parts and pointers/offsets into it.

* Part1 with actual update

** CRC32 + len

** Common header

** Information of decompressed size of TableOfContents (TOC), offset for info within TOC

** Information of different amount of updates (diffs, inserts, removals, links, etc.)

** Variable part depending on above information (e.g. old and new CRC32 of files, unused data for insert, unknown for other)

** LZMA TableOfContents (TOC) (needs to have uncompressed size in the header and no end-of-payload marker)

*** Starts with null terminated filenames to patch

*** List of file permissions (separated by 0xAF)

*** Information about updates (common header points to this offset). For inserts includes filesize, offset for permission, compressed size of update)

** LZMA of Insert (same requirement as above)

** Maybe some padding.. unknown about when to insert it

* Part2 with FileNamesTable

** CRC32 + len

** Common Information

** Len + null terminated string

<pre>

struct update_part_header {

   uint32_t crc32 // CRC32 of len + data

   uint32_t __le len; //

   uint8_t data[0];

};

</pre>

We have a python script to dissect the basic structure of a diff and another script to pack a file as insert in an upgrade. Image

updates were not studied.

h2. Kicking the recovery binary

* mount /dev/mtdblock14 /mnt..

* Place update.zip to /cache/

* echo "IP_START_UPDATE" > /cache/fota/ipth_config_dfs.txt  to say what to do

Was difficult to repeat, e.g. creating backup and mounting system partition failed on second/third tries

<pre>

/ # recovery 

mount: mounting none on /sys/kernel/debug failed: Device or resource busy

Starting recovery on Fri Oct 14 12:39:48 2016

recovery filesystem table

=========================

  0 /tmp ramdisk (null) (null) 0

  1 / auto rootfs (null) 0

  2 /proc proc proc (null) 0

  3 /dev/pts devpts devpts (null) 0

  4 /proc/bus/usb usbfs usbfs (null) 0

  5 /dev/shm tmpfs tmpfs (null) 0

  6 /cache yaffs2 /dev/mtdblock9 (null) 0

  7 /media/card auto /dev/mmcblk0p1 (null) 0

  8 /system yaffs2 /dev/mtdblock14 (null) 0

  9 /data yaffs2 /dev/mtdblock15 (null) 0

  10 /misc mtd /dev/mtdblock10 (null) 0

rootfs on / type rootfs (rw)

/dev/root on / type yaffs2 (rw,relatime)

proc on /proc type proc (rw,relatime)

sysfs on /sys type sysfs (rw,relatime)

tmpfs on /dev type tmpfs (rw,relatime,size=64k,mode=755)

devpts on /dev/pts type devpts (rw,relatime,mode=600)

tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777)

/dev/mtdblock15 on /usr type yaffs2 (rw,relatime)

/dev/mtdblock9 on /cache type yaffs2 (rw,relatime)

/dev/mtdblock13 on / type yaffs (rw,relatime)

tmpfs on /dev type tmpfs (rw,relatime,size=64k,mode=755)

/dev/mtdblock9 on /cache type yaffs2 (rw,relatime)

none on /sys type sysfs (rw,relatime)

none on /sys/kernel/debug type debugfs (rw,relatime)

proc on /proc type proc (rw,relatime)

total 3

lrwxrwxrwx    1 root     root            31 Jul 21 07:10 boot_hsic_composition -> /usr/bin/usb/compositions/empty

lrwxrwxrwx    1 root     root            30 Jul 21 07:10 boot_hsusb_composition -> /usr/bin/usb/compositions/9215

drwxr-xr-x    1 root     root          2048 Jul 21 07:10 compositions

crw--w----    1 root     root      247,   0 Jan  8  1970 /dev/ttyGS0

RB_Progress: fwrite "/dev/ttyGS1" fail

I:Checking delta update status...

handle_redbend_update: START_DELTA_UPDATE

I:Setting delta update status...

I:Delta update status is set to (IP_PREVIOUS_UPDATE_IN_PROGRESS 0)

I:Start delta update...

I:Setting recovery boot...

I:Recovery mode reached maximum retry. Clear boot message.

mtd: successfully wrote block at bebe0f4800000000

I:Set boot command ""

I:boot.command=

I:boot.recovery=

I:Update location: /cache/update.zip

I:number of files in zip is 1 

I:verifying file at index 0

I:No radio diff images found 

I:system.diff found 

E:No modem package available.

E:No modem update needed. returning O.K

mtd: successfully wrote block at bebe23a000000000

I:Reset FOTA cookie done.

start fota update (/cache/fota/system.diff)

redbend_fs_entry: device_name: /dev/mtdblock14

redbend_fs_entry: mount_point: /tmp/system

redbend_fs_entry: update_name: /cache/fota/system.diff

redbend_fs_entry: part_name: system

RB_GetDelta: offset 0x0(0), size 0x14(20)

RB_GetDelta: offset 0x0(0), size 0x18(24)

RB_GetDelta: offset 0x4(4), size 0x3508(13576)

RB_GetDelta: offset 0x0(0), size 0x40(64)

RB_GetDelta: offset 0x350c(13580), size 0x18(24)

RB_GetDelta: offset 0x3510(13584), size 0x27(39)

RB_GetDelta: offset 0x0(0), size 0x14(20)

RB_GetDelta: offset 0x0(0), size 0x18(24)

RB_GetDelta: offset 0x350c(13580), size 0x18(24)

RB_GetDelta: offset 0x0(0), size 0x18(24)

RB_GetDelta: offset 0x0(0), size 0x18(24)

RB_GetDelta: offset 0x350c(13580), size 0x18(24)

RB_GetDelta: offset 0x3524(13604), size 0x4(4)

RB_GetDelta: offset 0x3528(13608), size 0x4(4)

RB_GetDelta: offset 0x352c(13612), size 0x7(7)

RB_GetDelta: offset 0x0(0), size 0x40(64)

RB_GetDelta: offset 0x0(0), size 0x40(64)

RB_GetDelta: offset 0x40(64), size 0x304(772)

RB_GetDelta: offset 0x344(836), size 0xd(13)

RB_GetDelta: offset 0x351(849), size 0x4a8(1192)

FS partition delta dump

RedBend: Delta Info: delta_sig - 0x6d0d05e5

RedBend: Delta Info: delta_size - 13580

RedBend: Delta Info: ver - 82000

RedBend: Delta Info: scout_ver - 80000

RedBend: Delta Info: flags - 0x80000000

RedBend: Delta Info: runtype_flags - 0x280

RedBend: Delta Info: ram_size - 0x200c8

RedBend: Delta Info: sector_size - 0x40000

RedBend: Delta Info: dic_sz - 0xdc8

RedBend: Delta Info: compress_sz - 0x4b5

RedBend: Delta Info: min_alloc_ram_use - 0x22

RedBend: Delta Info: ext_info_sz - 2

RedBend: Delta Info: num_copy - 0

RedBend: Delta Info: num_diff - 95

RedBend: Delta Info: num_insert - 3

RedBend: Delta Info: num_delete - 0

RedBend: Delta Info: num_del_dirs - 0

RedBend: Delta Info: num_dirs - 0

RedBend: Delta Info: num_del_link - 0

RedBend: Delta Info: num_link - 4

RedBend: Delta Info: num_critical_update - 95

RedBend: Delta Info: num_critical_insert - 3

RB_CreateFolder: /cache/fota/a, mode:0x1ff

open file /cache/fota/a/backup

RB_OpenFile: Path:/cache/fota/a/backup | Mode: RDONLY 

 First open() with error 2

open file /tmp/system/etc/version

RB_OpenFile: Path:/tmp/system/etc/version | Mode: RDONLY 

 First open() with error 2

open file /tmp/system/etc/version

RB_OpenFile: Path:/tmp/system/etc/version | Mode: RDONLY 

 First open() with error 2

RedBend: Error in scout, file signature mismatch in file /tmp/system/etc/version

umount: can't umount /tmp/system: No such file or directory

fota update fail (/cache/fota/system.diff)

I:fs:/cache/update.zip update err

mtd: successfully wrote block at bebe23a000000000

I:Reset FOTA cookie done.

mtd: successfully wrote block at bebe0f3800000000

I:Set boot command ""

I:Setting delta update status...

I:Delta update status is set to (IP_PREVIOUS_UPDATE_FAILED 500)

handle_redbend_update: DELTA_UPDATE_IN_PROGRESS

I:Setting delta update status...

I:Delta update status is set to (IP_PREVIOUS_UPDATE_IN_PROGRESS 0)

I:Start delta update...

I:Setting recovery boot...

I:Error opening recovery count file. Ignore.

mtd: successfully wrote block at bebe0f4800000000

I:Set boot command "boot-recovery"

I:boot.command=boot-recovery

I:boot.recovery=recovery

I:Update location: /cache/update.zip

E:Can't open /cache/update.zip

(No such file or directory)

mtd: successfully wrote block at bebe0f3800000000

I:Set boot command ""

I:Setting delta update status...

I:Delta update status is set to (IP_PREVIOUS_UPDATE_FAILED 410)

mtd: successfully wrote block at bebe23a000000000

I:Reset FOTA cookie done.

RB_Progress: fwrite "/dev/ttyGS1" fail

precent:0 total:1 cur:1

Rebooting after recovery

I:Rebooting at the end of recovery module.

mtd: successfully wrote block at bebe0f8000000000

I:Set boot command ""

</pre>