`Charlotte Core`

The Kernel of CharlotteOS

Charlotte Core is the kernel of CharlotteOS. It is a hybrid kernel that is designed to provide a flexible and low level interface to software running ontop of it.

Status

Charlotte Core is the kernel of CharlotteOS. The kernel was redeveloped due to a lack of sufficient modularity and improper code organization which could not be easily refactored in place. Charlotte Core as it exists today is the result of that redevelopment though it does reuse a substantial amount of code from it's previous incarnation. A fork of the old Charlotte Core is available as an archive in the CharlotteOS GitHub organization.

Charlotte Core is in very early development and does not yet support a userspace. Run it at your own risk.

Implementation Languages

Charlotte Core is written in Rust and Assembly language

Target Platforms

x86_64 devices with UEFI and ACPI
RISC-V64GC devices with either UEFI and ACPI or the standard RISC-V bootflow using U-Boot and SBI

Building

The following commands are used to build the debug and release versions of the kernel.

make build-x86_64-debug    # debug
make build-x86_64-release  # release

Testing

make run-x86_64-debug    # For testing a debug build in qemu
make run-x86_64-release  # For testing a release build in qemu

The x86_64 portion of any of the previous commands can be replaced with riscv64 to build the kernel for the RISC-V architecture.

GDB debug probe

Follow the steps in the Building section above, replacing make run-x86_64-debug for run-x86_64-debugprobe, this will start qemu, but it will appear unresponsive this is because it's waiting for gdb to connect, on linux this can be achieved by in another terminal running:

gdb charlotte_core/target/x86_64-unknown-none/debug/charlotte_core

and once gdb is open:

(gdb) target remote localhost:1234
make sure to set some breakpoints or the code will just go straight to the halt at the end of main currently
(gdb) c

OR Use the .gdbinit file present in the repo, to do this you need to allow gdb to load the .gdbinit file, this can be accomplished by adding add-auto-load-safe-path [path to the repo here]/.gdbinit to $HOME/.config/gdb/gdbinit, wit this done you just need to run:

# in terminal 1
make run-x86_64-debugprobe
# in another terminal
gdb

if you are currently in the repo main folder you may use the snippet bellow to add the loading allow to gdbinit

mkdir -p $HOME/.config/gdb/;echo "add-auto-load-safe-path $(pwd)/.gdbinit" >> $HOME/.config/gdb/gdbinit

further reference Qemu GDB docs

Documentation

Detailed documentation will eventually be available in this repository's GitHub wiki and at CharlotteOS's website.

Contributing

Contributions are always welcome and highly appreciated. Please create a new branch for your work and submit a pull request on GitHub. Make sure to rebase all your changes on master to maintain a linear commit history avoiding merge commits to the extent possible. Feel free to grab any unassigned issues in the GitHub issue tracker for this repository.

Also please join our community on Discord to stay up to date with the latest on CharlotteOS development.

charlotte-os/charlotte-core

Charlotte Core