Get free stack size on Raspberry Pi Pico2 (RP2350)

[vasya-serega]

Hi,

who can have any ideas how to get free stack size on Raspberry Pi Pico2 (RP2350)?

On RP2040 we can call rp2040.getFreeStack() and get proper value. On RP2350 the method returns 270272 and it does not seem to be true.

Platform.ini is:

[env:5500_evb_pico2]
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = wiznet_5500_evb_pico2
board_build.core = earlephilhower
board_build.filesystem_size = 0.5m
framework = arduino
test_framework = unity
test_build_src = yes
build_flags = 
	'-D SHIELD="W5500-EVB-Pico2"'
build_unflags = -fno-rtti

[earlephilhower]

Good catch. There were hardcoded addresses for the stack locations which are different in the RP2350. #3255 fixes this, verified showing the Pico2 with just under 8K free in loop() with an empty sketch.

[maxgerhardt]

But is the linker script correct? No declaration of the full 520 kB?

arduino-pico/ota/memmap_ota_rp2350.ld

Lines 27 to 30 in db59e47

	RAM(rwx) : ORIGIN = 0x20000000, LENGTH = 212k
	GLOBALS(rwx) : ORIGIN = 0x20035000, LENGTH = 44k
	SCRATCH_X(rwx) : ORIGIN = 0x20080000, LENGTH = 4k
	SCRATCH_Y(rwx) : ORIGIN = 0x20081000, LENGTH = 4k

Edit: Ah that seems to be for OTA updates and https://github.com/earlephilhower/arduino-pico/blob/master/lib/rp2350/memmap_default.ld is handled dynamically.

[earlephilhower]

That's for the OTA shim, not the main app, so it's not used except to build the ota.o which needs ~40KB. It probably should be corrected at some point, but it's effectively a no-op as-is.