Origami is a x86_64 UEFI bootloader and boot protocol/specification meant for hobbist kernels, providing modern features like ACPI and KASLR while keeping things ultra-simple. It is inspired in Stivale boot protocol and in the now archived TomatBoot.
- Complete ELF load
- Higher half mapping
- Custom protocol
- Runs on baremetal
- Boot Menu
- KASLR and relocatable kernels support
- Level 5 paging
- Variable number of boot entries
You will need clang and lld; both of them use the LLVM architecture to cross compile apps, which will allow us to link the objects and transform the executable into a EFI app (see the Makefile for further information).
Run the command make all to generate a bootable UEFI app inside the bin folder. To test using QEMU run make test. You can speed up the build process (of building all the EDK2 library) by passing the flags -j <nproc + 1> -l <nproc> to the previous command.
Origami has been designed to provide hobbist OS developers an easy boot protocol to rely on. This means it is kept simple (following KISS philosophy) yet powerful, giving ACPI, UNIX Epoch and a frambuffer as the very basics to build great kernels, no SMP nor TTY support. Origami is not meant to replace Stivale or Multiboot; in fact, it is a project I did to learn.
Firstly copy the Spec file to the directory from where your kernel will be developed. Then create the kernel main file containing the entry point, a stack and the Origami header with the appropriate flags that suit your needs. You can take a look at the Test kernel. Modify the kernel entry point to do whatvere you want. Finally, create a linker.ld fileand fill it with the executable sections.
To build and test the kernel, I assume you understand what is a freestanding toolchain and a cross compiler and the args you have to pass to the compiler. The minimal command would look like gcc -nostdlib -ffreestanding -fno-stack-protector -fno-pic -mcmodel=kernel -mno-red-zone -mno-sse -mno-sse2 -c kernel.c -o kernel .o, and it will link with -nostdlib -static -fno-pic -z max-page-size=0x1000 -T linker.ld kernel.o -o kernel.elf.
Create a directory containing the following structure:
./
|__ EFI
|__ BOOT
Place the compiled BOOTX64.EFI file into the BOOT folder and the kernel.elf at the root. Then create origami.cfg at the root and fill it following the Spec.
Finally, issue qemu-system-x86_64 -machine q35 -m 4G -smp 4 -debugcon stdio -hda fat:rw:<directory name>.
Format an USB drive with FAT32 and follow steps above. Then shutdown your computer. disable Secure Boot and use the USB as boot drive.
When the kernel is booted, all the registers are set to 0 except rdi, which contains the boot parameters according to SysV x86_64 ABI, and rsp, which is set to the value of origami_header.stack. gBS->ExitBootServices() is called just before jumping into the kernel. The kernel must load its own GDT immediately.
The format used by Origami is very similar to Limine to keep the parser simple, using :Name to denote the boot entry name, PATH or KERNEL_PATH to indicate the kernel image file, CMDLINE to pass parameters to the kernel and TRACING to enabel bootloader debug messages.
An example can be found at config/example.cfg.
This project is hugely inspired by TomatBoot, using its library and build system; and also by the Stivale boot protocol.