# QEMU Kernel Booting

**Kernel booting** is the fastest way to test a freshly cross-compiled kernel without needing a full disk image. Load the kernel, device tree, and command-line arguments directly.

```bash
qemu-system-arm -M versatilepb -kernel zImage -dtb versatile.dtb \
  -append "console=ttyAMA0 earlycon" -nographic
```

`-kernel` loads the kernel image (typically `Image` or `zImage` depending on architecture). `-dtb` provides the device tree file that describes the board's memory layout, peripherals, and clocks. Without a device tree, the kernel cannot initialize hardware.

`-append` sets kernel command-line arguments passed at boot. `console=ttyAMA0` tells the kernel to use that serial port for output; `earlycon` enables serial output before the main console is initialized, useful for debugging early boot.

The `-nographic` flag redirects the serial port to your terminal. The kernel's boot output appears on stdout; you can interact with it as if it were a serial console.

Common QEMU boards for embedded testing:

```bash
qemu-system-arm -M versatilepb       # ARM Versatile PB (well-supported, stable)
qemu-system-riscv64 -M virt          # RISC-V virtual machine
qemu-system-arm -M raspi2            # Raspberry Pi 2 (partial support)
```

Kernel boot is read-only by default—no rootfs, no persistent filesystem. Good for testing boot sequence, but to test with a running system, use a disk image ([[qemu-disk-images]]).

The kernel panics and shuts down when it can't find init. Add `panic=1` to halt immediately on panic instead of looping indefinitely, useful for automated testing.