Qemu Qtest

QEMU qtest

Use this operational/domain skill for QEMU device and board tests using the qtest framework.

Flow relationship

• Use qemu-flow-plan to define the behavior claim and artifact root.
• Use qemu-build before running qtests if binaries are stale or missing.
• Use qemu-rlcr-loop when qtest findings drive iterative source changes.
• Store test logs, copied command lines, and debug notes under build/agent//.

Hard policy boundary

Do not produce source code intended for QEMU upstream submission. Do not add DCO or review trailers.

What qtest should prove

Use qtest for:

• MMIO/PIO register contracts;
• reset behavior;
• IRQ assertion/deassertion;
• virtual clock/timer behavior;
• QMP-visible state and hotplug;
• board instantiation and memory-map probes;
• simple DMA or guest-memory effects.

Prefer qtest over boot smoke for device contracts.

Running qtests

Run from a configured build directory. Default to build/.

List tests:

build/pyvenv/bin/meson test -C build --list

Run one test:

build/pyvenv/bin/meson test -C build qtest-riscv64/

Make frontends from inside build/:

make check-qtest
make check-qtest-riscv64
V=1 make check-qtest-riscv64

Use the narrow Meson test name when possible.

Finding/registering tests

Inspect:

• tests/qtest/meson.build for architecture buckets;
• tests/qtest/.c for source;
• tests/qtest/libqtest.h for API;
• build/meson-logs/testlog.txt for failures.

Register architecture-specific tests under the matching qtests_ list. Use qtests_generic only when the test is truly architecture-independent.

Useful libqtest APIs

• startup/shutdown: qtest_init(), qtest_initf(), qtest_quit();
• reset: qtest_system_reset();
• QMP/HMP: qtest_qmp(), qtest_qmp_assert_success(), qtest_qmp_eventwait(), qtest_hmp();
• MMIO: qtest_readb/readw/readl/readq(), qtest_writeb/writew/writel/writeq();
• memory: qtest_memread(), qtest_memwrite(), qtest_memset();
• PIO: qtest_inb/inw/inl(), qtest_outb/outw/outl();
• IRQ: qtest_irq_intercept_in(), qtest_irq_intercept_out(), qtest_set_irq_in();
• virtual clock: qtest_clock_step_next(), qtest_clock_step(), qtest_clock_set().

Use libqos/qgraph when nearby subsystem tests already do.

Device qtest checklist

• reset values;
• masks and reserved bits;
• read-only/write-only/W1C behavior;
• unsupported width behavior when guest-visible;
• IRQ level and clear path;
• virtual-clock timer expiry;
• DMA guest-memory effects;
• dirty-state reset.

Debugging qtests

Qtest environment variables include:

• QTEST_QEMU_BINARY
• QTEST_QEMU_ARGS
• QTEST_QEMU_IMG
• QTEST_QEMU_STORAGE_DAEMON_BINARY
• QTEST_STOP
• QTEST_LOG

Use verbose test output to recover exact commands. Use QTEST_STOP=1 when attaching a debugger to spawned QEMU is needed.

Portability rules

• Use GLib temp/file APIs.
• Avoid hardcoded /tmp.
• Avoid POSIX-only paths unless guarded.
• Use double quotes in extra QEMU command-line strings.
• Open binary files in binary mode when data comparison matters.

Report

Include:

• PASS/FAIL/INCONCLUSIVE;
• build dir;
• exact command;
• qtest name;
• decisive excerpt;
• log path;
• behavior proven and not proven.

Upstream references

• QEMU code provenance and AI policy: docs/devel/code-provenance.rst.
• QEMU RFC qemu-testing skill.
• Testing overview: docs/devel/testing/main.rst.
• QTest docs: docs/devel/testing/qtest.rst.
• API: tests/qtest/libqtest.h.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: processmission
• Source: processmission/oh-my-qemu
• License: MIT
• Homepage: https://processmission.github.io/oh-my-qemu/

Install and usage instructions live in the source repository linked above.