simpleboot/example

Simpleboot Example Kernels

This directory contains the source for very minimal kernels, that can be booted with Simpleboot (and Easyboot as well). All they do is dumping the received boot parameters to the serial console.

Compilation

make all

Will compile the example 64-bit Multiboot2-compatible ELF kernel and create the bootable disk image disk.img.

LINUX=1 make all

Creates a disk image with an example kernel that speaks the Linux/x86 Boot Protocol v2.12+ (needs objcopy).

MB32=1 make all

Creates a disk image with a 32-bit Multiboot2-compatible ELF kernel.

PE=1 make clean all

Creates a disk image with a 64-bit Multiboot2-compatible COFF/PE kernel (requires Clang + lld).

MB32=1 PE=1 make all

Creates a disk image with a 32-bit Multiboot2-compatible COFF/PE kernel (requires Clang + lld).

RPI=1 make clean all

Creates a disk image with a 64-bit Multiboot2-compatible kernel for the Raspberry Pi (requires Clang + lld).

RPI=1 PE=1 make clean all

Creates a disk image with a 64-bit Multiboot2-compatible COFF/PE kernel for the Raspberry Pi (requires Clang + lld).

make clean

Cleans the repo from the compiled binaries.

Plus all cases can be prefixed by HI=1 which will compile a higher half kernel, and SMP=1 will test Symmetric MultiProcessing (latter only with 64-bit Multiboot2-compatible ELF/COFF kernels, no Linux and no 32-bit).

Testing

make mnt

Mounts the boot partition inside the disk image so that you can examine its contents.

make qemu

Boots the disk image in qemu using BIOS (or Raspberry Pi if RPI set).

make efi

Boots the disk image in qemu using UEFI (you have to provide your own OVMF).

make cdrom

Boots the disk image in qemu using BIOS and El Torito "no emulation" mode. Use CDROM=1 make disk.img to generate a hybrid disk / cdrom image.

make eficdrom

Boots the disk image in qemu using UEFI and El Torito "no emulation" mode (you have to provide your own OVMF). Use CDROM=1 make disk.img to generate a hybrid disk / cdrom image.

make bochs

Boots the disk image in bochs using BIOS.

make rpi

Boots the disk image in qemu on Raspberry Pi.

make cb

Boots the disk image using coreboot. Note: this toolchain generates boot/mykernel, and coreboot will complain about not finding the kernel. To fix, either add boot/simpleboot.cfg too or use mv boot/mykernel boot/kernel; make cb (unlike with the other loaders, you cannot change the default name with -k because coreboot is a read-only ROM image, so only config file works).

Debugging

make qemudbg

Boots the disk image in qemu using BIOS, but does not start the VM.

make efidbg

Boots the disk image in qemu using UEFI, but does not start the VM.

make gdb

Run this in another terminal. It runs gdb, connects it to the stopped VM and starts execution. Because there's no symbol file, it's a bit tricky to use. Place 1:jmp 1b anywhere in the code, and press Ctrl+ C in the gdb's window. You'll see that the VM is running that jump. Use set $pc += 2 to step over the jump instruction, and after that you can do step by step execution with si, or continue with c.