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

h2. Start delta upgrade

<pre>

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

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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

It seems that /usr/bin/recovery will be started and finds a update.zip in the right partition and will then apply

the delta updates.

h2. Delta format

Delta updates are available for the bootloader (?), dsp, userdata and system. It is speculated that for the

system and userdata yaffs2 the actual filesystem will be mounted and individual files will be modified.

<pre>

struct upgrade_file_begin {

   uint32_t checksum; // ???? different in all of these upgrades

   uint32_t __le len; // len.. E.g. 184014 of a 184059 file

   ... still a lot of 32bit length.. not really TLV

};

struct upgrade_file_trailer {

  uint32_t __le len;

  char name[len]; with trailing \0

  uint32_t null_end (four bytes 0x00)

};

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