[PATCH 0/7] test: Add framebuffer test

[PATCH 0/7] test: Add framebuffer test

[Ahmad Fatoum]

QEMU allows taking screenshots of screen. Make use of this to enable
doing some rudimentary graphic tests.

Ahmad Fatoum (7):
  ARM: multi_v8_defconfig: enable QEMU ramfb driver
  test: enable VirtIO keyboard
  commands: fbtest: add flush for single pattern
  test: conftest: don't call .startswith on int
  test: conftest: set -display none when non-interactive
  test: conftest: add qemu feature
  test: add framebuffer screenshot testing via QMP screendump

 arch/arm/configs/multi_v8_defconfig   |  1 +
 commands/fbtest.c                     |  1 +
 conftest.py                           | 37 +++++++-------
 test/arm/virt@multi_v8_defconfig.yaml |  2 +
 test/py/helper.py                     | 53 +++++++++++++++++++
 test/py/test_fbtest.py                | 74 +++++++++++++++++++++++++++
 6 files changed, 149 insertions(+), 19 deletions(-)
 create mode 100644 test/py/test_fbtest.py

-- 
2.47.3

[PATCH 1/7] ARM: multi_v8_defconfig: enable QEMU ramfb driver

[Ahmad Fatoum]

Enable CONFIG_DRIVER_VIDEO_RAMFB so that barebox can drive the QEMU
ramfb display device. All dependencies (CONFIG_VIDEO,
CONFIG_QEMU_FW_CFG, CONFIG_FS_QEMU_FW_CFG) are already enabled.

This will allow framebuffer testing with --graphics on the QEMU Virt
platform later.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 arch/arm/configs/multi_v8_defconfig   | 1 +
 test/arm/virt@multi_v8_defconfig.yaml | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/arm/configs/multi_v8_defconfig b/arch/arm/configs/multi_v8_defconfig
index a6cc49859620..d2f04d30a422 100644
--- a/arch/arm/configs/multi_v8_defconfig
+++ b/arch/arm/configs/multi_v8_defconfig
@@ -222,6 +222,7 @@ CONFIG_USB_GADGET_MASS_STORAGE=y
 CONFIG_VIDEO=y
 CONFIG_FRAMEBUFFER_CONSOLE=y
 CONFIG_DRIVER_VIDEO_BOCHS_PCI=y
+CONFIG_DRIVER_VIDEO_RAMFB=y
 CONFIG_SOUND=y
 CONFIG_MCI=y
 CONFIG_MCI_MMC_BOOT_PARTITIONS=y
diff --git a/test/arm/virt@multi_v8_defconfig.yaml b/test/arm/virt@multi_v8_defconfig.yaml
index 2e654359709e..4eb75da4610e 100644
--- a/test/arm/virt@multi_v8_defconfig.yaml
+++ b/test/arm/virt@multi_v8_defconfig.yaml
@@ -17,6 +17,8 @@ targets:
       - network
       - barebox-state
       - testfs
+    env:
+      nv/dev.fb0.enable: 1
 images:
   barebox-qemu-virt.img: !template "$LG_BUILDDIR/images/barebox-qemu-virt.img"
 imports:
-- 
2.47.3

[PATCH 2/7] test: enable VirtIO keyboard

[Ahmad Fatoum]

The QEMU ARM64 Virt machine has no input method by default.
As we already had VirtIO input for the web demo, enable it when
--graphic is enabled.

The barebox VirtIO input driver was ported from Linux and both support
only VirtIO v1 devices, so we need to explicitly set
virtio-mmio.force-legacy=false for this to work.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 conftest.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/conftest.py b/conftest.py
index b0d314f3f345..c27e7a9546a1 100644
--- a/conftest.py
+++ b/conftest.py
@@ -175,6 +175,7 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
 
     if "virtio-mmio" in features:
         virtio = "device"
+        strategy.append_qemu_args('-global virtio-mmio.force-legacy=false')
     if "virtio-pci" in features:
         virtio = "pci,disable-modern=off"
         features.append("pci")
@@ -210,6 +211,7 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
             graphics = '-device VGA'
         elif virtio:
             graphics = '-vga none -device ramfb'
+            graphics += f' -device virtio-keyboard-{virtio}'
         else:
             pytest.exit("--graphics unsupported for target\n", 1)
 
-- 
2.47.3

[PATCH 3/7] commands: fbtest: add flush for single pattern

[Ahmad Fatoum]

The single-pattern else-branch calls gu_screen_blit() to copy the render
buffer to the framebuffer in-memory image, but never called fb_flush()
to make sure the image makes it to display RAM.

Add fb_flush(sc->info) after gu_screen_blit(), matching the cycling
path above.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 commands/fbtest.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/commands/fbtest.c b/commands/fbtest.c
index cee72b039371..40c97f72a442 100644
--- a/commands/fbtest.c
+++ b/commands/fbtest.c
@@ -297,6 +297,7 @@ static int do_fbtest(int argc, char *argv[])
 	} else {
 		pattern(sc, color);
 		gu_screen_blit(sc);
+		fb_flush(sc->info);
 	}
 done:
 	fb_close(sc);
-- 
2.47.3

[PATCH 4/7] test: conftest: don't call .startswith on int

[Ahmad Fatoum]

The returned YAML value may be an integer if quotes are missing, which
will lead to an error when .startswith() is called on it.

Check that the value is a string first and while at it, combine the two
loops to reduce the duplicate code.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 conftest.py | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/conftest.py b/conftest.py
index c27e7a9546a1..6bf92f3afed7 100644
--- a/conftest.py
+++ b/conftest.py
@@ -226,25 +226,17 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
         else:
             pytest.exit("--blk unsupported for target\n", 1)
 
+    envopts = {}
+
     for i, fw_cfg in enumerate(pytestconfig.option.qemu_fw_cfg):
+        value = fw_cfg.pop()
+        envpath = fw_cfg.pop() if fw_cfg else f"data/fw_cfg{i}"
+
+        envopts[envpath] = value
+
+    for envpath, value in (yaml_env | envopts).items():
         if virtio:
-            value = fw_cfg.pop()
-            envpath = fw_cfg.pop() if fw_cfg else f"data/fw_cfg{i}"
-
-            if value.startswith('@'):
-                source = f"file='{value[1:]}'"
-            else:
-                source = f"string='{value}'"
-
-            strategy.append_qemu_args(
-                '-fw_cfg', f'name=opt/org.barebox.env/{envpath},{source}'
-            )
-        else:
-            pytest.exit("--env unsupported for target\n", 1)
-
-    for envpath, value in yaml_env.items():
-        if virtio:
-            if value.startswith('@'):
+            if isinstance(value, str) and value.startswith('@'):
                 source = f"file='{value[1:]}'"
             else:
                 source = f"string='{value}'"
-- 
2.47.3

[PATCH 5/7] test: conftest: set -display none when non-interactive

[Ahmad Fatoum]

When running QEMU with --graphic, but in a non graphical session,
running QEMU may fail because it fails to start e.g. the GTK window.

Allow headless tests for these configurations by adding -display none.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 conftest.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/conftest.py b/conftest.py
index 6bf92f3afed7..d02e5aff998f 100644
--- a/conftest.py
+++ b/conftest.py
@@ -215,6 +215,10 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
         else:
             pytest.exit("--graphics unsupported for target\n", 1)
 
+        if graphics is not None and \
+                pytestconfig.option.lg_initial_state != 'qemu_interactive':
+            graphics += ' -display none'
+
         strategy.append_qemu_args(graphics)
 
     for i, blk in enumerate(pytestconfig.option.qemu_block):
-- 
2.47.3

[PATCH 6/7] test: conftest: add qemu feature

[Ahmad Fatoum]

This will allow skipping tests that explicitly require qemu features,
like the incoming screendump in the grpahical tests.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 conftest.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/conftest.py b/conftest.py
index d02e5aff998f..72d2df792e6d 100644
--- a/conftest.py
+++ b/conftest.py
@@ -168,8 +168,9 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
     try:
         main = target.env.config.data["targets"]["main"]
         qemu_bin = main["drivers"]["QEMUDriver"]["qemu_bin"]
+        features.append("qemu")
     except KeyError:
-        qemu_bin = None
+        pass
 
     virtio = None
 
@@ -202,7 +203,7 @@ def strategy(request, target, pytestconfig):  # noqa: max-complexity=30
         else:
             pytest.exit("barebox currently supports only a single extra virtio console\n", 1)
 
-    if qemu_bin is not None:
+    if "qemu" in features:
         if not pytestconfig.option.qemu_graphics:
             graphics = '-nographic'
         elif qemu_bin == "qemu-system-x86_64":
-- 
2.47.3

[PATCH 7/7] test: add framebuffer screenshot testing via QMP screendump

[Ahmad Fatoum]

Add screendump() and parse_ppm() helpers to capture and parse QEMU
framebuffer screenshots using the QMP screendump command. Use them in a
new test that draws a solid color with fbtest and verifies the pixels
match. The test auto-skips when no framebuffer is available (e.g. without
--graphics).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 test/py/helper.py      | 53 ++++++++++++++++++++++++++++++
 test/py/test_fbtest.py | 74 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 test/py/test_fbtest.py

diff --git a/test/py/helper.py b/test/py/helper.py
index ab615280048f..2e3bc489d88a 100644
--- a/test/py/helper.py
+++ b/test/py/helper.py
@@ -6,6 +6,7 @@ import os
 import re
 import shlex
 import subprocess
+import tempfile
 
 
 def parse_config(lines):
@@ -200,6 +201,58 @@ def skip_disabled(config, *options):
             pytest.skip("skipping test due to disabled " + (",".join(undefined)) + " dependency")
 
 
+def parse_ppm(path):
+    """Parse a PPM P6 (binary) image file.
+
+    Returns (width, height, data) where data is bytes of RGB pixel values.
+    Pixel (x, y) starts at offset (y * width + x) * 3.
+    """
+    with open(path, 'rb') as f:
+        magic = f.readline().strip()
+        assert magic == b'P6', f"Expected P6, got {magic}"
+
+        line = f.readline()
+        while line.startswith(b'#'):
+            line = f.readline()
+
+        width, height = map(int, line.split())
+        maxval = int(f.readline().strip())
+        assert maxval == 255
+
+        data = f.read()
+        expected = width * height * 3
+        assert len(data) == expected, \
+            f"Expected {expected} bytes, got {len(data)}"
+
+    return width, height, data
+
+
+def screendump(qemu, path=None):
+    """Capture a QEMU framebuffer screenshot via QMP screendump.
+
+    Args:
+        qemu: A labgrid QEMUDriver instance.
+        path: Optional host path for the PPM file. If None, a temp file is used.
+
+    Returns:
+        (width, height, data) tuple from parse_ppm().
+    """
+    if qemu is None:
+        pytest.skip("screendump requires a QEMU target")
+
+    cleanup = path is None
+    if path is None:
+        fd, path = tempfile.mkstemp(suffix='.ppm')
+        os.close(fd)
+
+    try:
+        qemu.monitor_command('screendump', {'filename': path})
+        return parse_ppm(path)
+    finally:
+        if cleanup:
+            os.unlink(path)
+
+
 def ensure_debian_iso(env, destdir):
     """
     Extract Debian kernel and initrd from ISO into destdir.
diff --git a/test/py/test_fbtest.py b/test/py/test_fbtest.py
new file mode 100644
index 000000000000..58b70d7dc4ab
--- /dev/null
+++ b/test/py/test_fbtest.py
@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+import hashlib
+import pytest
+from .helper import skip_disabled, screendump
+
+
+@pytest.fixture(autouse=True)
+def check_fbtest_in_qemu(barebox, env, barebox_config):
+    skip_disabled(barebox_config, "CONFIG_CMD_FBTEST")
+
+    if 'qemu' not in env.get_target_features():
+        pytest.skip("fbtest tests only possible with QEMU")
+
+    _, _, ret = barebox.run("test -e /dev/fb0")
+    if ret != 0:
+        pytest.skip("no framebuffer device available")
+
+
+def assert_solid_color(data, width, height, color):
+    """Verify that sampled pixels in the lower half match the expected color."""
+    sample_points = [
+        (width // 2, height * 3 // 4),
+        (width // 4, height * 3 // 4),
+        (width * 3 // 4, height * 3 // 4),
+        (width // 2, height - 2),
+    ]
+
+    r_exp = (color >> 16) & 0xff
+    g_exp = (color >> 8) & 0xff
+    b_exp = color & 0xff
+
+    for x, y in sample_points:
+        off = (y * width + x) * 3
+        r, g, b = data[off], data[off + 1], data[off + 2]
+        assert abs(r - r_exp) < 10, f"pixel ({x},{y}): R={r}, expected {r_exp}"
+        assert abs(g - g_exp) < 10, f"pixel ({x},{y}): G={g}, expected {g_exp}"
+        assert abs(b - b_exp) < 10, f"pixel ({x},{y}): B={b}, expected {b_exp}"
+
+
+def test_fb_solid_color(barebox, barebox_config, strategy):
+    color = 0xff0000
+    barebox.run_check(f"fbtest -p solid -c {color:06x}")
+
+    width, height, data = screendump(strategy.qemu)
+    assert_solid_color(data, width, height, color)
+
+
+def screendump_hash(qemu):
+    """Capture a screenshot and return a hash of the pixel data."""
+    _, _, data = screendump(qemu)
+    return hashlib.sha256(data).hexdigest()
+
+
+def test_fb_patterns_distinct_and_stable(barebox, barebox_config, strategy):
+    patterns = ["solid", "geometry", "bars", "gradient"]
+
+    # Render each pattern twice and collect hashes
+    hashes = {p: [] for p in patterns}
+
+    for run in range(2):
+        for pattern in patterns:
+            barebox.run_check(f"fbtest -p {pattern} -c ffffff")
+            hashes[pattern].append(screendump_hash(strategy.qemu))
+
+    # Same pattern must produce the same output across runs
+    for pattern in patterns:
+        assert hashes[pattern][0] == hashes[pattern][1], \
+            f"pattern '{pattern}' produced different output across runs"
+
+    # Different patterns must produce different output
+    unique = set(hashes[p][0] for p in patterns)
+    assert len(unique) == len(patterns), \
+        f"expected {len(patterns)} distinct patterns, got {len(unique)}"
-- 
2.47.3

Re: [PATCH 0/7] test: Add framebuffer test

[Sascha Hauer]

On Mon, 13 Apr 2026 09:44:43 +0200, Ahmad Fatoum wrote:
> QEMU allows taking screenshots of screen. Make use of this to enable
> doing some rudimentary graphic tests.
> 
> Ahmad Fatoum (7):
>   ARM: multi_v8_defconfig: enable QEMU ramfb driver
>   test: enable VirtIO keyboard
>   commands: fbtest: add flush for single pattern
>   test: conftest: don't call .startswith on int
>   test: conftest: set -display none when non-interactive
>   test: conftest: add qemu feature
>   test: add framebuffer screenshot testing via QMP screendump
> 
> [...]

Applied, thanks!

[1/7] ARM: multi_v8_defconfig: enable QEMU ramfb driver
      https://git.pengutronix.de/cgit/barebox/commit/?id=1e1b3b66677a (link may not be stable)
[2/7] test: enable VirtIO keyboard
      https://git.pengutronix.de/cgit/barebox/commit/?id=50c2aabc574b (link may not be stable)
[3/7] commands: fbtest: add flush for single pattern
      https://git.pengutronix.de/cgit/barebox/commit/?id=af2a6133e535 (link may not be stable)
[4/7] test: conftest: don't call .startswith on int
      https://git.pengutronix.de/cgit/barebox/commit/?id=80554888f677 (link may not be stable)
[5/7] test: conftest: set -display none when non-interactive
      https://git.pengutronix.de/cgit/barebox/commit/?id=74693d62342f (link may not be stable)
[6/7] test: conftest: add qemu feature
      https://git.pengutronix.de/cgit/barebox/commit/?id=af5b226aa085 (link may not be stable)
[7/7] test: add framebuffer screenshot testing via QMP screendump
      https://git.pengutronix.de/cgit/barebox/commit/?id=3fb451e0110a (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>