How _‘‘long’’_ it is? Over a year? Given i’ve got my laptop’s ALL the blobs using `flashrom`, but how to _‘‘write’’_ those code for those blobs?
In summary, it's a long process of writing and testing mainboard
specific code that enables coreboot to do exactly the right things to initialize the hardware on your mainboard far enough that an operating system or boot loader can run.
Not all nations have their own stores selling SPI programmers, if unfortunately *none* are selling them, then i’m *unlikely* able to start committing Coreboot tasks
External flashing means that you don't use the laptop's own southbridge
(flashrom -p internal ...) to interface with the flash chip, but rather a flash programmer that is external to the laptop's own electronics, for example a Bus Pirate or a CH341A-based programmer, that is connected to the flash chip with a SOIC-8/SOIC-16 clip.
Note that in most cases the flash chip that holds the BIOS or coreboot
uses the SPI protocol and is not compatible SD or microSD cards.