No warning on >100% ram usage

[non-bin]

In Marlin, I couldn't figure out why compiling with FT_MOTION caused the board to freeze during boot, until I noticed it reporting negative free memory.

Is it possible to add at least a warning for high memory usage?
I'm not very familiar with where gcc, pio, and the marlin build config start and end, so this may need to be a gcc feature

Build log

Executing task: C:\Users\jacka\.platformio\penv\Scripts\platformio.exe run --target upload 

Processing mega2560 (board: megaatmega2560; platform: atmelavr@~4.0.1; framework: arduino)
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/atmelavr/megaatmega2560.html
PLATFORM: Atmel AVR (4.0.1) > Arduino Mega or Mega 2560 ATmega2560 (Mega 2560)
HARDWARE: ATMEGA2560 16MHz, 8KB RAM, 248KB Flash
DEBUG: Current (avr-stub) External (avr-stub, simavr)
PACKAGES:
 - framework-arduino-avr @ 5.1.0
 - tool-avrdude @ 1.60300.200527 (6.3.0)
 - toolchain-atmelavr @ 1.70300.191015 (7.3.0)
Converting Marlin.ino
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 5 compatible libraries
Scanning dependencies...
Dependency Graph
|-- Wire @ 1.0
|-- SPI @ 1.0
Building in release mode
Compiling .pio\build\mega2560\src\src\HAL\AVR\HAL.cpp.o

...

Compiling .pio\build\mega2560\src\src\sd\cardreader.cpp.o
Linking .pio\build\mega2560\firmware.elf
Checking size .pio\build\mega2560\firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [==========]  193.5% (used 15849 bytes from 8192 bytes)
Flash: [========  ]  77.5% (used 196936 bytes from 253952 bytes)
Building .pio\build\mega2560\firmware.hex
Configuring upload protocol...
AVAILABLE: wiring
CURRENT: upload_protocol = wiring
Looking for upload port...
Auto-detected: COM4
Uploading .pio\build\mega2560\firmware.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.04s

avrdude: Device signature = 0x1e9801 (probably m2560)
avrdude: reading input file ".pio\build\mega2560\firmware.hex"
avrdude: writing flash (196936 bytes):

Writing | ################################################## | 100% 49.25s

avrdude: 196936 bytes of flash written
avrdude: verifying flash memory against .pio\build\mega2560\firmware.hex:
avrdude: load data flash data from input file .pio\build\mega2560\firmware.hex:
avrdude: input file .pio\build\mega2560\firmware.hex contains 196936 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 42.33s

avrdude: verifying ...
avrdude: 196936 bytes of flash verified

avrdude: safemode: Fuses OK (E:FD, H:D8, L:FF)

avrdude done.  Thank you.

================================================================================== [SUCCESS] Took 309.48 seconds ==================================================================================
Environment    Status    Duration
-------------  --------  ------------
mega2560       SUCCESS   00:05:09.482
=================================================================================== 1 succeeded in 00:05:09.482 =================================================================================== *  Terminal will be reused by tasks, press any key to close it. 

MarlinFirmware/Marlin#26451

[ivankravets]

Thanks for the report! Fixed.