Intel Pushes A Bunch Of Broadwell Code Into Coreboot

[uid313]

But usually both the BIOS and UEFI come heavily customized from each motherboard manufacturer, I imagine their not cross compatible (seeing as not all motherboards have the same featureset and options to configure) if it overwrites the firmware won't this be a problem? configuring the motherboard that is..

The motherboard manufacturers licenses a implementation of BIOS or UEFI from a firmware developer such as Phoenix, American Megatrends Inc (AMI) or Insyde Software.

This implementation has support for common chipsets such as Intel Z87, Z97, X99, and AMD 900-series chipsets. Then the motherboard configures the firmware for each of their motherboards to load the relevant modules for hardware support and configure the logo and strings for manufacturer, product, version, etc.

Coreboot also has support for multiple chipsets and hardware.
So Coreboot does essential hardware setup and configuration then executes a payload stored in the firmware. That payload may be SeaBIOS (a open source BIOS implementation) or TianoCore (a open source UEFI implementation) or GNU GRUB (the bootloader) or the Linux kernel directly.

When you flash Coreboot into firmware, you flash the Coreboot firmware image built for your motherboard (which contains modules for the chipset on your motherboards). You do not flash a big monolithic general-purpose image.