Your tiny OS as BIOS replacement

Good day!
I'm one of the coreboot users/developers. This is FOSS alternative to legacy BIOS/EFI. It let boot any elf image, or SeaBIOS (which provide legacy bios services).
And it's pretty small. So, as usually modern BIOS flash chips are big, you can place your tiny own OS in ROM.
As example, i'm working on booting KolibriOS from coreboot. Now it booting oveer SeaBIOS, but i'm hope exclude SeaBIOS stage from booting.

First of all - please, read our wiki http://www.coreboot.org/
Found supported hardware http://www.coreboot.org/Supported_Motherboards
and decide which you have to try coreboot, or you can use QEMU.

1. Download&configure&build:

Code:

svn co svn://coreboot.org/coreboot/trunk coreboot
cd coreboot
make menuconfig

You need to choose:

Code:

Mainboard -> Mainboard Vendor -> Emulation 
Mainboard -> Mainboard Model -> QEMU x86

for producing image for qemu. Then run

Code:

make

2. Output will be in coreboot.rom inside build directory.
3. Download vgabios image for qemu from http://www.coreboot.org/images/0/0d/Vgabios-cirrus.zip
4. You need latest qemu (0.14 or from git)
3. Copy coreboot.rom in working directory, rename it into bios.bin
Copy vgabios-cirrus.bin here also.
4. Run qemu with

Code:

qemu -L . -cdrom kolibri.iso -serial stdio

where kolibri.iso is kolibrios image, but can be your own OS image. "-L ." option point qemu to directory where bios.bin and vgabios-cirrus.bin files.

here is my example image:

Code:

coreboot.rom: 4096 kB, bootblocksize 1504, romsize 4194304, offset 0x0
Alignment: 64 bytes

Name                           Offset     Type         Size
cmos_layout.bin                0x0        unknown      1159
fallback/romstage              0x4c0      stage        12720
fallback/coreboot_ram          0x36c0     stage        27797
fallback/payload               0xa3c0     payload      40596
(empty)                        0x142c0    null         4110104

Also you can pack OS image in rom:
I'm using kolibri.img (floppy image):

Code:

lzma -zc kolibri.img > kolibri.img.lzma
./build/cbfstool coreboot.rom add kolibri.img.lzma floppyimg/Kolibri.lzma raw

where cbfstool in build directory of coreboot tree.
you can check now result with:

Code:

./build/cbfstool coreboot.rom print

Now you can also rename coreboot.rom into bios.bin for your working directory and try boot with qemu.

Also, coreboot let you boot:

directly boot 32-bit code
have no bugs usual for BIOS (see http://www.coreboot.org/Security)
Have support from AMD ( http://blogs.amd.com/work/2011/02/28/technical-details-coreboot/ + http://blogs.amd.com/work/2011/02/28/amd-coreboot/ )
Its faster and smaller. See http://www.coreboot.org/Benefits

For additional info, please read first:
http://www.coreboot.org/FAQ

http://www.coreboot.org/Developer_Manual
http://www.coreboot.org/Payloads
http://www.coreboot.org/SeaBIOS
http://www.coreboot.org/FILO
http://www.coreboot.org/Libpayload
http://www.coreboot.org/Payload_API

For flashing your image you can use flashrom utility (http://www.flashrom.org) - please always use latest (from svn) version!!!

For debugging this on real hardware you can use SerialICE http://www.serialice.com/

I'm attaching ready image and some files from libpayload to show how-to work with coreboot specifics