BIOS for baremetal programs on x86

Question

Is it a good idea to use the BIOS interrupts INT10? Or should I consider coreboot, UFEI or openFirmware? Are these compatible? What should I use to display to the screen?

Answer 1

You're mixing up a couple of entirely unrelated things here.

• Coreboot is an alternative to the PC BIOS which is not available for all motherboards, and which must be specifically installed by the user. It must always run a payload, which may be something like the Linux kernel, or an open-source PC BIOS such as SeaBIOS (at which point, it's largely indistinguishable from any other PC BIOS).

• UEFI is an alternative to the PC BIOS which is more advanced, but considerably harder to code for. It almost always contains compatibility routines for the standard PC BIOS.

• Open Firmware is a rough equivalent to the PC BIOS used on some other platforms, including PowerPC Macs and some Sun systems. It's never been used on an x86 system that I'm aware of, so it's almost certainly uninteresting to you.

If you are programming for a bare-metal x86 system, then interrupt 10h is probably the way to go. The next alternative to consider would be accessing the VGA hardware directly.