How to create a bootloader to flash not using espflash?

[yanshay]

I want to flash my application (which is based on esp-hal) on a blank esp32s3 not using esp-flash, and as separate parts (so bootloader, partition table and application image).

I know how to flash the application itself.
I know how to flash the partition table.
But when I flash the bootloader (of esp32s3) found here, it fails to work and the device goes into restarts with error:
E (55) flash_parts: partition 4 invalid - offset 0x30000 size 0x300000 exceeds flash chip size 0x200000

I guess that's because I need to modify the bootloader for my exact chip because it has inside settings for smaller memory and maybe other values I need to modify.

How can I generate the proper bootloader for my device?

[yanshay]

Answering in case someone in the future needs this.
Easiest way I found was:

1. Find in this repo the bootloader you need for your chip and check the bin size (let's assume it is 21008 - esp32s3).
2. Flash some demo app to your device.
3. run espflash read-flash 0 21008 esp32s3-bootloader-downloaded.bin and you have a bootloader file as was generated in (2) for yout device.