KAM Bootloader

An x86 + ARM64 bootloader written in C. Freestanding, no libc: one UEFI C source builds for both x86_64 and AArch64, plus a BIOS path (512-byte MBR + stage2 trampoline + C payload) for x86.

• UEFI: x86_64 + AArch64 from a single source.
• BIOS: x86 MBR + stage2 (16-bit real mode to 64-bit long mode).
• ARM64 is UEFI-only; there is no MBR/BIOS outside x86.

• ELF64 kernels through a shared prepare/commit loader (BIOS + UEFI), with a fixed test kernel stub proving load, params and jump.
• Third-party .EFI binaries via LoadImage/StartImage chainload.
• bzImage direct boot: setup probe, initrd, cmdline, params page with e820/cmdline/ramdisk at genuine offsets, handover entry.
• ISO9660 + El Torito probe, Windows layout detection, GOP header art.
• Static KAM/KAM.INI config (labels, timeout, default, salted SHA-256 boot password, per-entry initrd/cmdline) merged with a dynamic multi-volume scan (own ESP, other disks, data partitions; dedupe by path).
• An in-memory boot log mirrored to ConOut and flushed to KAM/BOOT.LOG. The password gate logs only outcomes, never secrets.

include/kam/   -> headers (UEFI, BIOS, ELF, ISO, config, crypto)
src/uefi/      -> UEFI app, both arches from one C source
src/bios/      -> MBR (512B) + 16-to-64 stage2 trampoline + C payload
src/kernel/    -> test kernel stub (both arches)
src/linux/     -> bzImage test fixture (both arches)
linker/        -> per-arch linker scripts
tools/         -> image builders (mkesp/mkiso/mkusb/mkpasswd),
                  inspectors (isoinfo/imgcheck/fatread),
                  QEMU drivers (drive_boot, shot_boot)
tests/         -> host unit tests (no firmware needed)
.github/       -> CI workflow (full matrix on ubuntu-latest)

macOS:

brew install nasm lld llvm qemu

Linux (same as CI):

sudo apt-get install -y nasm llvm clang lld \
  qemu-system-x86 qemu-system-arm ovmf qemu-efi-aarch64

On Linux the Makefile defaults (Homebrew paths) are overridden:

make test-all LLVM=/usr/bin CLANG_CL=/usr/bin/clang-cl \
  QEMU_X64_FW=/usr/share/OVMF/OVMF_CODE_4M.fd \
  QEMU_AA64_FW=/usr/share/AAVMF/AAVMF_CODE.fd

make test-all   # full matrix: BIOS + UEFI x64/aa64 + media + host checks

Interactive runs (no assertions, watch the console yourself):

make run-bios
make run-x64
make run-aa64

make test-all runs everything below. QEMU tests boot real firmware (SeaBIOS/OVMF on x64, EDK2 virt on aa64) and assert serial output; shot_boot additionally screenshots the display and asserts GOP pixels.

Line-based, no allocation, unknown sections/keys are ignored:

timeout 5
default 1

[kernel]
label My Kernel
path \KAM\KERNEL.ELF

[chain]
label Hello
path \KAM\HELLO.EFI

[iso]
label Test ISO
path \KAM\TEST.ISO

[linux]
label Test Linux
path \KAM\VMLINUZ
initrd \KAM\INITRD.IMG
cmdline kam-test console=ttyS0

password_salt COST164
password_hash <64 hex chars of SHA-256(salt + password)>

Generate the password lines with:

python3 tools/mkpasswd.py --password kamboot --salt COST164 --timeout 5

Only the salted hash is stored; the password itself is never written anywhere.

• tools/mkesp.py: partitioned ESP disk image (bootable FAT16 ESP, optional second data partition, or partitionless superfloppy for El Torito EFI boot images). Pure Python, no mtools.
• tools/mkiso.py: minimal ISO9660 image with El Torito catalog, carrying both a BIOS boot path and an EFI boot image.
• tools/mkusb.py: USB stick image: MBR + BIOS payload in the alignment gap + ESP volume in partition 1, so one image boots both BIOS and UEFI.
• tools/isoinfo.py, tools/imgcheck.py, tools/fatread.py: host-side inspectors used by the tests (ISO listing, FAT structural audit, file extraction).

.github/workflows/ci.yaml installs the Linux dependencies above and runs make test-all on ubuntu-latest for every push and pull request.