.ld scripts refactoring

[mcspr]

Fixes arduino/Arduino#1260

• distribute two sets of ldscripts
• automatically pick proper ldscript via platformio python extra script
• additional flash sizes for Generic board
• float support ON/OFF menu option for IDE
• ldscript generator (sector calculation included, based on boards.txt.py script from Core)

Arduino IDE (only tested with 2.5.0 release):

copy proper ldscripts into the <esp8266-package-dir>/tools/sdk/ld
copy boards.local.txt into the <esp8266-package-dir>
run / restart IDE, select ESPurna board in the menu

PlatformIO

same as above, but happens automatically
added platform = ${common.arduino_core_git} and platform = ${common.arduino_core_2_5_0} to allow testing with the newest Core

TODO

boards.local.txt generator script Done
ldscript generator Done
maybe try to find out different way to detect core version (platform.txt? parse framework package version?) Done (Checking 'local....' presence)

[mcspr]

Also trying out draft PRs.
I do not see travis build, so here it is: https://travis-ci.org/mcspr/espurna/builds/495245870

[mcspr]

When building from IDE, it generates special string that describes settings. Like this:

$ grep fqbn $TMP/arduino_build_446496/build.options.json
"fqbn": "esp8266com:esp8266:espurna:xtal=160,vt=flash,exceptions=disabled,ResetMethod=ck,CrystalFreq=26,FlashFreq=40,FlashMode=dout,ip=lm2f,float_support=disabled,variant=esp8285,eesz=1M,wipe=none,baud=115200"

If board definition has some defaults (espurna.build.f_cpu=80 instead of espurna.menu.blablabla.80.build.f_cpu=80), it is possible to launch cli tools with fqbn just being esp8266com:esp8266:espurna to build "default" flavour.
https://github.com/arduino/arduino-builder, arguments for which can be copied from IDE build log
https://github.com/arduino/arduino-cli, which is merciful and only wants fqbn setting

Ofc it is not compatible between versions (search SUBSTITUTIONS in boards script)

[Niek]

I think it's possible to pre-process the LD files with the compiler and use something like DEFINED(ARDUINO_ESP8266_RELEASE_2_5_0) to include the correct file. See https://sourceware.org/binutils/docs/ld/Builtin-Functions.html#Builtin-Functions

[mcspr]

But binutils DEFINED and preprocessor defined() are different things. That is a linker script level expression, checking if symbol exists. Example given uses ternary expression to assign symbol some default value. And even then, are there global level if/else expressions to use it?

But we can do something like this:

$ cat check.sh.in
#include <core_version.h>
#if defined(ARDUINO_ESP8266_RELEASE_2_3_0) || defined(ARDUINO_ESP8266_RELEASE_2_4_2)
echo old
#else
echo new
#endif
$ cc -x c -P -E -I~/.platformio/packages/framework-arduinoespressif8266@2.20402.2/cores/esp8266 check.sh.in -o check.sh
$ bash check.sh
old

BTW, Arduino Core does use preprocessor to generate that file

[Niek]

OK, I haven't tested too much with the DEFINED() in binutils.

Another option would be to use regular C #define statements in the ld files and preprocess them with something like gcc -E -x c -C eagle.flash.1m0m1s.ld | grep -v "^# " - but the bash script probably makes more sense.

[Niek]

That diff is exactly what I have now in my linker script, and it works fine (with PIO). Either that or utils.ino and eeprom need to be ifdef-ed with the correct macro name.
By the way is anybody seriously building Espurna with IDE? I tried it once but it takes an hour to gather all dependencies with the correct versions etc. PIO is just so much better IMHO.

[mcspr]

Yeah, and an interesting note from the Tasmota issue tracker:
arendst/Tasmota#6073 (comment)

We do reference include inside tools/sdk/ld, so it does (?) work ok, or at least how it always worked before. But, we can't exactly not use them with 2.3.0 and rely on default scripts. We still need those aliases for some time, so I'll add this as a temporary solution (and to speed up -git builds setup time)

I'll try to come up with a reasoning for Core issue tracker and open an issue there regarding FS... symbols usage (or some other way to use them through helper methods)
Rotate lib can be forked or imported inside / be submodule / lib header
boards.local kind of solves this too, since our scripts have different names

[Niek]

FYI the SPIFFS symbols have been added to core as well now: esp8266/Arduino@418b00f