Baremetal Example

A minimal baremetal kernel that demonstrates basic hardware initialization and UART output on multiple architectures. This project supports both ARM64 (AArch64) and SPARC v8 (AJIT) platforms, providing a foundation for bare-metal systems programming and hardware experimentation.

ARM64 (AArch64)

Build instructions

• Run ./download_toolchain_arm64.sh to download the ARM64 baremetal toolchain.
• Run make or make ARCH=arm64 to build the kernel for ARM64.

Running instructions

• Make sure you have qemu-system-aarch64 on your machine. If not, install with sudo apt install qemu-system-arm
• Once qemu is installed, run ./run_qemu_arm64.sh
• For debugging, run ./run_qemu_arm64.sh debug to start QEMU with GDB server enabled
• Tested on qemu version v10.1.0

Status

• Arm64 virt board boots fine & printing stuff through PL011 UART works.

SPARCv8 (AJIT)

Build instructions

• Download the custom AJIT QEMU model from here
• Run ./download_toolchain_sparcv8.sh to download the SPARCv8 baremetal toolchain.
• Run make ARCH=sparc to build the kernel for SPARCv8.

Running instructions

• Ensure the custom qemu-system-sparc binary is in your PATH
• Once qemu is installed, run ./run_qemu_ajit.sh. Enter c at the qemu monitor.
• For debugging, run ./run_qemu_ajit.sh debug to start QEMU with GDB server enabled
• Note: The AJIT machine uses a remote serial connection (PTY). The serial device path will be displayed when QEMU starts.

Connecting to the serial console

The AJIT QEMU model uses a PTY (pseudo-terminal) for serial communication. To view the output:

1. Start QEMU with ./run_qemu_ajit.sh - note the PTY device path in the output (e.g., /dev/pts/X)
2. In a separate terminal, connect using minicom:

   minicom -D /dev/pts/X

   Replace X with the actual PTY number from QEMU's output
3. If minicom is not installed, install it with: sudo apt install minicom
4. To exit minicom, press Ctrl-A followed by X

Status

• SPARC v8 AJIT model with UART, Timer, & Interrupt controller works.
• The dummy kernel code just tests the UART TX though by printing stuff.

Debugging with GDB

GDB debugging is available for both architectures. The process is the same:

1. Start QEMU in debug mode:
   • For ARM64: ./run_qemu_arm64.sh debug
   • For SPARCv8: ./run_qemu_ajit.sh debug
2. In a separate terminal, start GDB and connect using:

   gdb-multiarch -x connect.gdb

3. Set breakpoints and debug as needed.