The irom0_flash.bin file gets written to offset 0x40000 in flash. Said file
has the following layout
| irom0 | text | data | rodata | chksum |
...so the previous approach of having a _flash_used_end symbol at the end of
the irom0 section no longer gives us an accurate view of how much of the flash
is used.
A fair bit of reshuffling with include paths and overrides was necessary, as
the two RTOS SDKs (ESP8266 and ESP32) don't have the same header structure
(or even libraries for that matter). Uses the xtensa-esp108-elf toolchain
to build.
Completely untested beyond linking, as I still can't flash the ESP32 module
I have :( I'd be most surprised if it does anything useful at this point
considering I've spent almost no time on the linker script or UART setup.
Anything using espconn has been ifdef'd out since espconn is not (and
probably will not be) available. Notably this includes the entire net module
as well as coap, mqtt and enduser_setup.
Many (most?) hardware bus drivers and related modules are also ifdef'd
out for now due to hardware differences. Functions surrounding sleep,
rtc and RF modes have also been hit by the ifdef hammer. Grep'ing for
__ESP8266__ and/or FIXME is a quick way of finding these places. With
time I hope all of these will be reinstated.