I am curious as to how it survives the coreboot flash re-write, maybe the EC?
e.g.
Base Board Information Manufacturer: LENOVO Product Name: 4291QT1 Version: ThinkPad X220 Serial Number: XYZU1234...
comes from a small i2c eeprom (at24 based). src/drivers/i2c/at24rf08c/lenovo_serials.c
best, lynxis
ps: The at24 also contains your lenovo bios password.