idea for a way to store data in flash from running program

Can somebody tell me if this would be possible or not (and why)? Seems like it could be very useful.

Bootloader looks into eeprom during startup it adds the data from eeprom into a location in flash (maybe have the first part of the eeprom data be instructions for where to store it) run program program does it's thing. now you can also read the data that is saved into flash at some point, I want to store more data. so, write more data to the eeprom and trigger a reset process repeats...

This way if you needed more non-volatile storage than the amount of eeprom you have (like you want to record 5k of data), you could use your extra flash space instead. I know it would be slow, but in some cases that doesn't really matter. I'm mostly interested in if this would be possible or not. I mentioned this in another thread I had asked a question in, but it seemed like an idea that should have its own topic to me.

Sounds like it would work. You just need to write the bootloader changes.

Sounds messy. Why not just have your code write the data into a large external FRAM? Writes fast like SRAM, yet has EEPROM data retention, and waaaay higher rewrite capability than EEPROM or FLASH

For example

"The MB85RC128 is a FRAM (Ferroelectric Random Access Memory) Stand-Alone chip in a configuration of 16,384 words × 8 bits, using the ferroelectric process and silicon gate CMOS process technologies for forming the nonvolatile memory cells. The MB85RC128 adopts the two-wire serial interface. Unlike SRAM, the MB85RC128 is able to retain data without using a data backup battery. The read/write endurance of the nonvolatile memory cells used for the MB85RC128 has improved to be at least 1010 cycles, significantly out performing Flash memory and E2PROM in the number. The MB85RC128 does not need a polling sequence after writing to the memory such as the case of Flash memory nor E2PROM."

Mouser used to carry 256K x 8 parts for like $5.77, but their prices seemed to have skyrocketed recently.

I agree, that using extra parts would be way simpler to implement. I was just curious about if it could be done. I'll try to understand what this pile of hieroglyphics aka the bootloader code actually means. Maybe if I stare at it for a few months or years, I can figure out what I'm doing and give it a try. Or if anybody with some actual knowledge wants to give it a shot...

Well, the whole intent of the bootloader to date seems to have been to minimize it to fit in a small segment and to leave more room for a sketch. Adding code to allow a sketch to access something from the bootloader to write to flash would bump the bootloader into the next segment size. Same for your special application. I'm not a good enough coder to jump into that.