How to store an array in flash memory (only) using the pico sdk?

Question

The RP2040 on my board (Seeeduino XIAO) comes with 2MB of flash ram.

How can I store an array that is too large to fit into RAM in flash, using C and the pico sdk?

As the array exceeds a certain size, the linker throws errors like this one:

[  0%] Linking CXX executable test.elf
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: test.elf section `.data' will not fit in region `RAM'
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: region RAM overflowed
/usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: region `RAM' overflowed by 182056 bytes

With Arduino, I could just add PROGMEM like so and be done with it:

const PROGMEM uint8_t samples[] = { ... }

This does however not work with the pico sdk.

Answer 1

Following and slighly modifying the suggestions on the Raspberry Pi forum I got it to work. __in_flash() is what needs to be added:

#include <pico/platform.h>

const uint8_t __in_flash() samples [] = {

This way, I can now use an array of 442615 bytes that would not fit into the 264k internal RAM.