runtime: pull_labs: emit tuxrun parameters for legacy FVP trees

config/runtime/base/pull_labs.jinja2

@@ -77,6 +77,13 @@
     "url": "{{ instance_callback }}/node/{{ node.id }}",
     "token_name": "{{ callback_token_name | default('kernelci-pipeline-callback') }}"
   }
+{%- if tuxrun_parameters %}
+  ,"parameters": {
+{%- for k, v in tuxrun_parameters.items() %}
+    "{{ k }}": "{{ v }}"{{ "," if not loop.last else "" }}
+{%- endfor %}
+  }
+{%- endif %}
 {%- if node.artifacts.metadata %}
   ,"integrity": {
     "sha256": {

kernelci/runtime/pull_labs.py

@@ -269,6 +269,28 @@ def get_log_parser(self):
         return LogParser(log)
 
 
+LEGACY_FVP_ARCH_VERSION = {
+    "linux-5.15.y": "9.5",
+    "linux-6.1.y": "9.5",
+}
+
+
+def compute_tuxrun_parameters(platform_name, node):
+    """Build tuxrun --parameters K=V values per job.
+
+    Clamps FVP_ARM_ARCH_VERSION on FVP jobs for legacy trees that
+    cannot boot on newer Arm architecture versions.
+    """
+    params = {}
+    if platform_name and platform_name.startswith("fvp-"):
+        branch = (
+            node.get("data", {}).get("kernel_revision", {}).get("branch", "")
+        )
+        if branch in LEGACY_FVP_ARCH_VERSION:
+            params["FVP_ARM_ARCH_VERSION"] = LEGACY_FVP_ARCH_VERSION[branch]
+    return params
+
+
 class PullLabs(Runtime):
     """Runtime implementation for PULL_LABS protocol
 
@@ -288,6 +310,9 @@ def get_params(self, job, api_config=None):
         params = super().get_params(job, api_config)
         params["timeout"] = self.config.timeout
         params["poll_interval"] = self.config.poll_interval
+        params["tuxrun_parameters"] = compute_tuxrun_parameters(
+            job.platform_config.name, job.node
+        )
         return params
 
     def generate(self, job, params):

tests/test_runtime.py

@@ -12,6 +12,7 @@
 
 import kernelci.config
 import kernelci.runtime
+from kernelci.runtime.pull_labs import compute_tuxrun_parameters
 
 
 class _FakeResponse:
@@ -345,3 +346,40 @@ def post_handler(url, payload):
     job_id = lab._submit("jobdef")
     assert job_id == 123
     assert captured["json"]["definition"] == "jobdef"
+
+
+def _node_with_branch(branch):
+    return {"data": {"kernel_revision": {"branch": branch}}}
+
+
+def test_compute_tuxrun_parameters_legacy_fvp():
+    """Old stable trees on FVP clamp to an older Arm arch version."""
+    for branch in ("linux-5.15.y", "linux-6.1.y"):
+        params = compute_tuxrun_parameters(
+            "fvp-aemva", _node_with_branch(branch)
+        )
+        assert params == {"FVP_ARM_ARCH_VERSION": "9.5"}
+
+
+def test_compute_tuxrun_parameters_modern_fvp():
+    """Mainline and modern stable trees on FVP keep the default arch version."""
+    for branch in ("master", "linux-6.6.y", "linux-6.12.y", "linux-next"):
+        params = compute_tuxrun_parameters(
+            "fvp-aemva", _node_with_branch(branch)
+        )
+        assert params == {}
+
+
+def test_compute_tuxrun_parameters_non_fvp():
+    """Non-FVP platforms get no tuxrun parameters regardless of branch."""
+    for platform in ("qemu-arm64", "rpi4", "rk3588"):
+        params = compute_tuxrun_parameters(
+            platform, _node_with_branch("linux-5.15.y")
+        )
+        assert params == {}
+
+
+def test_compute_tuxrun_parameters_missing_branch():
+    """Nodes lacking kernel_revision.branch get an empty parameter set."""
+    assert compute_tuxrun_parameters("fvp-aemva", {}) == {}
+    assert compute_tuxrun_parameters("fvp-aemva", {"data": {}}) == {}