Standalone HMP monitor for QEMU, communicating exclusively through QMP.

When QAPI was added, some 15 years ago, the plan was to migrate every HMP command over to QMP. Fast forward to today, and that goal is still a work in progress—mostly because manual conversion is not bringing much benefit. I decided to see if LLMs could handle the heavy lifting. After a few hours of prompting Claude to replicate HMP via the QMP API, I was able to map out the missing pieces. This is the result of this experiment.

• "reedline" support, with history, bindings etc
• both HMP and QOM
• QOM events!
• completions, including QOM tree, block devices, enum values, keyval
• inlined "kitty" screendump!
• QOM socket auto-discovery
• aiming at feature parity

cargo build

To build against a different QEMU source tree:

QEMU_SCHEMA_DIR=/path/to/qemu cargo build

# Start QEMU with a QMP socket:
qemu-system-x86_64 ... -qmp unix:/tmp/qmp.sock,server,wait=off

# Interactive mode (auto-discovery):
qemu-hmp

# Batch mode:
qemu-hmp -s /tmp/qmp.sock -c "info version" -c "info cpus"

# Pipe mode (stdin is not a terminal):
echo "info version" | qemu-hmp -s /tmp/qmp.sock

Pipe mode emits a NUL byte (\0) after each response for machine parsing.

cargo test

To verify output parity with QEMU's built-in HMP:

python3 tests/compare_hmp.py [--qemu /path/to/qemu-system-x86_64]

• test coverage
• requires various new x- commands to be added to QEMU
• device_add / object_add etc don't have good completion
• no deprecated commands
• qemu-io is out of scope

GPL-2.0-or-later