This page documents coreboot usage with NetBSD. It is probably terser than it could be, as it mostly just describes differences from the more-commonly-documented Linux procedures.
building coreboot on NetBSD
GNU make is required to build coreboot, install it from pkgsrc/devel/gmake.
Use coreboot/util/crossgcc, you may have to work around a issue with the path to the GCC sources.
building SeaBIOS on NetBSD
Build SeaBIOS with the previously mentioned crossgcc. You may need to (temporarily) use pkgsrc/shells/bash as your shell.
using NetBSD/x86 with coreboot
Legacy interrupt routing (the PCI interrupt line register) is traditionally not implemented by coreboot on many mainboards. MPBIOS or ACPI will be required otherwise.
NetBSD does not (without patching) search for a MPBIOS floating pointer at the location coreboot usually places it. SeaBIOS does relocate this pointer structure however.
(This section is probably only relevant when not loading via SeaBIOS.)
NetBSD/i386 GENERIC still makes some BIOS calls after boot(8):
Removal of these subsystems from your kernel config(5) file removes these calls.
Due to the nature of x86_64, BIOS calls on NetBSD/amd64 are not a problem, as they cannot be made from long-mode.
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