Piotr Piwko wrote:
Does coreboot support executing of boostrap which is contained in MBR?
No. coreboot itself doesn't really do operating system bootstrapping.
Maybe you have any hints about writing payload which can do that?
As Joseph pointed out you could look at SeaBIOS, which has quickly become a very complete BIOS implementation. SeaBIOS runs well as a coreboot payload, and if you combine coreboot and SeaBIOS you will indeed have a legacy compatible open source firmware.
//Peter