- Revise firmware implementation notes
- Document how to do fw syscalls
- Document how to trigger a syscall function in the firmware, how to
pass arguments, what the caller is responsible for and what is
returned.
- Describe hardware syscall implementation
- how the syscall interrupts are triggered,
- the hardware privilege escalation,
- the UDS protection.
Co-authored-by: Daniel Jobson <jobson@tillitis.se>
Co-authored-by: Michael Cardell Widerkrantz <mc@tillitis.se>
In order to be able to leave data for firmware signalling the
intention with a reset or to leave data for the next app in a chain of
apps, we introduce a part of FW_RAM that can be used to store this
data. In order to do this, we:
- Change size of ROM from 6 KB to 8 KB.
- Change size of FW_RAM, from 2 KB to 4 KB.
- Add RESETINFO memory partition inside FW_RAM.
- Add generation of map file.
- Change CFLAGS from using -O2 to using -Os.
- Update address ranges for valid access to ROM and FW_RAM.
- Move stack to be located before data+bss and the RESETINFO data
above them. This also means we introduce hardware stack overflow
protection through the Security Monitor.
- Revise firmware README to the new use of FW_RAM.
- The API changes name from `_SWITCH_APP` to `_SYSTEM_MODE_CTRL`.
- The registers and wires changes name to `system_mode_*`, instead of a
mix of `switch_app_*` and `fw_app_mode`.
- Remove the define `NOCONSOLE`, add define `QEMU_CONSOLE`
- Inverse the use of it, add the define to have QEMU debug output in fw.
- Add a make target `qemu_firmware.elf` which builds the firmware with
QEMU console enabled.
Co-authored-by: Mikael Ågren <mikael@tillitis.se>
- Remove all text about other software than firmware.
- Remove the Reset section.
- Include a diagram and detailed explanation about the state machine
in close vicinity.
- Describe the test firmware.
Co-authored-by: Joachim Strömbergson <joachim@assured.se>
