I've added to /opt/retropie/emulators/retroarch/retroarch.cfg:

input_enable_hotkey_btn = 8
input_exit_emulator_btn = 9

based on http://nickbartlett.com/retropie-emulationstation-not-saving-game-progress/.

To /opt/retropie/configs/all/retroarch.cfg, I've added:

# Automatically saves a savestate at the end of RetroArch's lifetime.
# The path is $SRAM_PATH.auto.
# RetroArch will automatically load any savestate with this path on startup if savestate_auto_load is set.
savestate_auto_save = true
savestate_auto_load = true

# Autosaves the non-volatile SRAM at a regular interval. This is disabled by default unless set otherwise.
# The interval is measured in seconds. A value of 0 disables autosave.
autosave_interval = 5

And I have no other configs that would overwrite those in /opt/retropie/configs/snes/retroarch.cfg:

# Settings made here will only override settings in the global retroarch.cfg if placed above the #include line

input_remapping_directory = "/opt/retropie/configs/snes/"

#include "/opt/retropie/configs/all/retroarch.cfg"

I watch the file that should change when I make progress, but nothing happens!

watch -d "ls -al ~/RetroPie/roms/snes/Legend*.state.auto"

I'm on retropie version:

pi@retropie:~/RetroPie-Setup $ git show
commit c522c722b6753b1908d7f5fa00b4bc1e105e514a

I tried running with verbose logging by pressing a on launching the ROM. It seems to add the --verbose logging option:

/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-snes9x2010/snes9x2010_libretro.so --config /opt/retropie/configs/snes/retroarch.cfg /home/pi/RetroPie/roms/snes/LegendofZeldaALinktothePast.sfc --verbose --appendconfig /dev/shm/retroarch.cfg

I haven't found yet where the logs are going.

Is there a command to flush the state from ram to that file?