Boot flow

The ISO and direct-QEMU targets both start the Linux kernel with a compressed CPIO initramfs. The kernel command line selects:

rdinit=/usr/bin/bdsh-init

rdinit selects the init program inside the initramfs. Buildroot installs the bdsh-init console entry point, which calls bdsh.init:main. That entry point creates the shell data directories and starts the minimal shell as user default; it does not ask for a login or start the BadLogon and network services.

ISO menu

The GRUB menu in kernel/iso/grub.cfg provides two entries:

• Start BadOS uses the VGA virtual terminal (tty0).
• Start BadOS (serial mode) uses ttyS0 at 115200 baud.

The shell accepts keyboard input through the selected console. In the graphical entry, focus the QEMU display window to type. The serial entry is intended for a connected serial console or a terminal attached to QEMU’s serial output.

Live filesystem and persistence

The CPIO filesystem is expanded into RAM at boot. Files created or changed during a session, including shell profiles and package installs, disappear when the machine shuts down. The ISO does not install BadOS to a disk or provide persistent user data.

Entropy device

QEMU is configured with a virtio random-number device. The required kernel drivers expose it to the system; this supplies random data used by Python and password hashing during startup and login.