The Caliga Bootloader

I am designing a multi-architecture bootloader to use in future OS projects.

Currently working on the bootstrap process for aarch64 and x86_64-UEFI.

Build

For now, this section is very brief, but I plan to expand it so that it can be really easy to build the bootloader and test it out.

Note: Don't use the -j argument when running make. As cargo handles most of the build process, allowing make to use multiple threads does not improve the build speed.

Build and Run With Qemu

To quickly test out the boot loader's aarch64 implementation, run the following:

make qemu

Only Build

If you just want to build and not run in qemu, remove 'qemu' from the arguments:

make

Note about UEFI Firmware

It may be difficult to run for x86_64-unknown-uefi because the build system currently assumes that OVMF will be used from one of the default Linux paths (/usr/share/**/OVMF.fd).

If it's not found, then it will be compiled from scratch. This may fail if you don't have all the OVMF build dependencies, listed here. I will soon change this so that it will instead be automatically downloaded, but I haven't found a reliable source yet.

Switch Target Architecture

If you want to run a different architecture, export its target triple under the variable RUST_TARGET:

export RUST_TARGET=x86_64-unknown-uefi
make qemu

If you only want to change the architecture for a single run, use the following command:

RUST_TARGET=x86_64-unknown-uefi make qemu

Run Tests

Tests (currently including integration and documentation tests) should be easy to run:

make test

Supported Targets

The only target triples currently supported are:

• aarch64-unknown-none
• x86_64-unknown-uefi

Goals

Here's a checklist of some goals for this bootloader. Each goal is for both x86_64 and aarch64 and will only be checked off when implemented for both platforms:

• Entry point
• Panic handler
• Default text output device (uart for aarch64, efi_text_output for x86_64)
• Default logger
• Global allocator
• Slab allocator
• Intrusive linked list
• Linked list allocator
• Out of memory handler
• Initial method of loading kernel image (embedded ELF section for aarch64 and simple file system for x86_64 UEFI)
• Elf loader
• Address mapping
• Pass data to kernel (EFI table, DTB, ACPI table, etc.)
• Construct memory map
• Start running kernel

Further goals:

• RAM disk driver
• Block device drivers
• File system drivers

x86_64 Status

Some current parts of the x86_64 bootloader utilize the uefi_services crate to accomplish the previous goals.

I plan to wean off the features of this crate by slowly re-implementing them myself. This includes the following:

• Entry point
• Panic handler
• Default text output device
• Default logger
• Global allocator
• Out of memory handler