: Choose your source (e.g., a "Hard Disk" for a USB flash drive or an "ISO" file).

Previous versions used synchronous serial polling. Version 4.0 introduces an asynchronous event loop that can handle multiple VMs simultaneously. You can now boot-test 20 different kernel configurations on 20 different QEMU instances in the same time it used to take for one.

: Developers use QEMU to sanity-check uncompressed kernel binaries (supported since QEMU 4.0) to ensure they aren't "completely busted" before moving to physical metal. Expert Tips for Use

qemu-boot-tester run test.yaml --verbose

Test warm reboot, cold reboot, and ACPI S3 sleep/resume by saving and restoring VM snapshots. This allows you to test bootloader persistence and NVRAM behavior.

: You can dynamically allocate system memory to the test environment, supporting up to 16 GB of RAM in newer iterations to simulate higher-end hardware environments.