minutes OTA meetup 13.2.2015

#Attendees

• Jeff Katz (kiwi.ki)
• Trevor Jordan (kiwi.ki)
• Arvid Picciani (airfy)
• Christian Mehlis (airfy)
• Ludwig Ortmann (airfy / FU Berlin)
• Hans Christian (FU Berlin)

#goal of the meeting

define a common architecture for over the air full-system updates (excluding network protocol)

#OTA identified use cases

• separate update code from main code
• download with any high level protocol
• encrypted and signed images
• protection against power loss during flash
• sometimes limited internal flash
• binary diffs to save bandwidth/rx power (for example bsdiff)
• relocate update code to ram

Architecture agreement

as per this PDF sent to the ML (OTA Taskforce)

• minimalistic bootloader, which may execute app specific strategy out of:
  • copy from ext to internal storage
  • select other region to boot, trigger watchdog, expect AOK flag from new image or fallback
  • relocate itself to ram and run dangerous in-place ota
• logical assignment in board config of storage to enums for OTA regions and key/value store
  • multiple OTA regions must be supported to have multiple images available on offline storage
• existing crypto apis seems fairly good to implement signature checks
• common relocation support
• config store for bootreason and AOK flag will be eating an entire erase sector.
• no common image format will be defined. checking for wether it makes sense to flash a certain image are left to the application
• all the apis are designed to work on complete images

Open questions:

• is there a smaller version of elf?
• unclear if storage type abstraction is necessary

Other

• common interest in implementing a v4 stack, should probably discuss that in the network task force