tests/functional/x86_64: Add vhost-user-bridge test
Introduce a functional test of vhost-user-bridge and enter it into MAINTAINERS under the vhost section. The test runs vhost-user-bridge as a subprocess, then launches a guest with four backends: a unix domain socket for vhost-user, a UDP socket, a user-mode net, and a hubport to hub the UDP and user backends; only the vhost-user backend is exposed, the rest are deviceless. This configuration mimics the testing setup described in the initial commit of vhost-user-bridge in 3595e2eb0a23. The test creates a scratch file containing a hardcoded UUID on the host and exposes it to the the guest via the tftp parameter of the user netdev. After the guest invokes tftp to request the file, the test verifies the transfer by hashsum. Similarly, the test creates a file with another hardcoded UUID in the guest. A call to check_http_download() serves the file to the host via http, whereupon a check of the file hashsum occurs on the host. Lastly, add the test to the thorough tests suite in meson.build. Suggested-by: Cédric Le Goater <clg@redhat.com> Suggested-by: Marc-André Lureau <marcandre.lureau@gmail.com> Suggested-by: Michael S. Tsirkin <mst@redhat.com> Suggested-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Signed-off-by: Yodel Eldar <yodel.eldar@yodel.dev> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Message-Id: <20260129133049.119829-3-yodel.eldar@yodel.dev>
Yodel Eldar committed
Jan 29, 2026 at 07:30 UTC
051364b36b2c68058f7e6d2204ef2a877b0bb221
3 files changed
+149
MAINTAINERS
+1
@@ -2406,6 +2406,7 @@ F: subprojects/libvhost-user/
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F: block/export/vhost-user*
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F: util/vhost-user-server.c
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F: net/vhost*
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+F: tests/functional/x86_64/test_vhost_user_bridge.py
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vhost-shadow-virtqueue
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R: Eugenio Pérez <eperezma@redhat.com>
tests/functional/x86_64/meson.build
+1
@@ -34,6 +34,7 @@ tests_x86_64_system_thorough = [
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'reverse_debug',
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'tuxrun',
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'vfio_user_client',
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+ 'vhost_user_bridge',
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'virtio_balloon',
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'virtio_gpu',
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]
tests/functional/x86_64/test_vhost_user_bridge.py
new
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@@ -0,0 +1,147 @@
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+#!/usr/bin/env python3
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+#
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+# Copyright (c) 2025 Software Freedom Conservancy, Inc.
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+#
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+# Author: Yodel Eldar <yodel.eldar@yodel.dev>
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+#
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+# SPDX-License-Identifier: GPL-2.0-or-later
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+"""
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+Test vhost-user-bridge (vubr) functionality:
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+
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+ 1) Run vhost-user-bridge on the host.
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+ 2) Launch a guest VM:
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+ a) Instantiate a unix domain socket to the vubr-created path
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+ b) Instantiate a vhost-user backend on top of that socket
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+ c) Map a virtio-net-pci device to the vhost-user backend
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+ d) Instantiate a UDP socket backend
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+ e) Instantiate a user-mode net backend
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+ i) Forward an ephemeral port to port 8080 in-guest with hostfwd=
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+ ii) Expose a generated scratch file to the guest with tftp=
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+ f) Hub the UDP and user-mode backends.
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+ 3) Invoke tftp in the guest to download exported scratch file from the host.
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+ 4) Serve a file to the host via http server in the guest.
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+"""
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+
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+import os
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+import shutil
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+import subprocess
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+from qemu_test import Asset, LinuxKernelTest, which
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+from qemu_test import exec_command_and_wait_for_pattern
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+from qemu_test import is_readable_executable_file
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+from qemu_test import wait_for_console_pattern
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+from qemu_test.ports import Ports
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+
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+class VhostUserBridge(LinuxKernelTest):
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+
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+ ASSET_KERNEL_INITRAMFS = Asset(
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+ "https://github.com/yodel/vhost-user-bridge-test/raw/refs/heads/main/bzImage",
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+ "8860d7aa59434f483542cdf25b42eacae0d4d4aa7ec923af9589d1ad4703d42b")
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+
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+ HOST_UUID = "ba4c2e39-627f-487d-ae3b-93cc5d783eb8"
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+ HOST_UUID_HSUM = \
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+ "d2932e34bf6c17b33e7325140b691e27c191d9ac4dfa550f68c09506facb09b9"
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+
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+ GUEST_UUID = "143d2b21-fdf0-4c5e-a9ef-f35ebbac8945"
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+ GUEST_UUID_HSUM = \
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+ "14b64203f5cf2afe520f8be0fdfe630aafc1e85d1301f55a0d1681e68881f3a2"
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+
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+ def configure_vm(self, ud_socket_path, lport, rport, hostfwd_port, tftpdir):
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+ self.require_accelerator("kvm")
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+ self.require_netdev("vhost-user")
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+ self.require_netdev("socket")
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+ self.require_netdev("hubport")
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+ self.require_netdev("user")
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+ self.require_device("virtio-net-pci")
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+ self.set_machine("q35")
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+ self.vm.add_args(
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+ "-cpu", "host",
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+ "-accel", "kvm",
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+ "-append", "printk.time=0 console=ttyS0",
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+ "-smp", "2",
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+ "-m", "128M",
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+ "-object", "memory-backend-memfd,id=mem0,"
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+ "size=128M,share=on,prealloc=on",
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+ "-numa", "node,memdev=mem0",
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+ "-chardev", f"socket,id=char0,path={ud_socket_path}",
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+ "-netdev", "vhost-user,id=vhost0,chardev=char0,vhostforce=on",
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+ "-device", "virtio-net-pci,netdev=vhost0",
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+ "-netdev", f"socket,id=udp0,udp=localhost:{lport},"
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+ f"localaddr=localhost:{rport}",
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+ "-netdev", "hubport,id=hub0,hubid=0,netdev=udp0",
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+ "-netdev", f"user,id=user0,tftp={tftpdir},"
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+ f"hostfwd=tcp:127.0.0.1:{hostfwd_port}-:8080",
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+ "-netdev", "hubport,id=hub1,hubid=0,netdev=user0"
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+ )
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+
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+ def assemble_vubr_args(self, vubr_path, ud_socket_path, lport, rport):
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+ vubr_args = []
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+
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+ if (stdbuf_path := which("stdbuf")) is None:
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+ self.log.info("Could not find stdbuf: vhost-user-bridge "
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+ "log lines may appear out of order")
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+ else:
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+ vubr_args += [stdbuf_path, "-o0", "-e0"]
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+
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+ vubr_args += [vubr_path, "-u", f"{ud_socket_path}",
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+ "-l", f"127.0.0.1:{lport}", "-r", f"127.0.0.1:{rport}"]
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+
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+ return vubr_args
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+
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+ def test_vhost_user_bridge(self):
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+ prompt = "~ # "
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+ host_uuid_filename = "vubr-test-uuid.txt"
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+ guest_uuid_path = "/tmp/uuid.txt"
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+ kernel_path = self.ASSET_KERNEL_INITRAMFS.fetch()
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+
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+ vubr_path = self.build_file("contrib", "vhost-user-bridge",
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+ "vhost-user-bridge")
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+ if not is_readable_executable_file(vubr_path):
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+ self.skipTest("Could not find a readable and executable "
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+ "vhost-user-bridge")
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+
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+ vubr_log_path = self.log_file("vhost-user-bridge.log")
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+ self.log.info("For the vhost-user-bridge application log,"
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+ f" see: {vubr_log_path}")
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+
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+ sock_dir = self.socket_dir()
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+ ud_socket_path = os.path.join(sock_dir.name, "vubr-test.sock")
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+
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+ tftpdir = self.scratch_file("tftp")
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+ shutil.rmtree(tftpdir, ignore_errors=True)
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+ os.mkdir(tftpdir)
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+ host_uuid_path = self.scratch_file("tftp", host_uuid_filename)
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+ with open(host_uuid_path, "w", encoding="utf-8") as host_uuid_file:
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+ host_uuid_file.write(self.HOST_UUID)
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+
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+ with Ports() as ports:
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+ # pylint: disable=unbalanced-tuple-unpacking
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+ lport, rport, hostfwd_port = ports.find_free_ports(3)
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+
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+ self.configure_vm(ud_socket_path, lport, rport, hostfwd_port,
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+ tftpdir)
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+
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+ vubr_args = self.assemble_vubr_args(vubr_path, ud_socket_path,
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+ lport, rport)
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+
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+ with open(vubr_log_path, "w", encoding="utf-8") as vubr_log, \
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+ subprocess.Popen(vubr_args, stdin=subprocess.DEVNULL,
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+ stdout=vubr_log,
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+ stderr=subprocess.STDOUT) as vubr_proc:
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+ self.launch_kernel(kernel_path, wait_for=prompt)
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+
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+ exec_command_and_wait_for_pattern(self,
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+ f"tftp -g -r {host_uuid_filename} 10.0.2.2 ; "
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+ f"sha256sum {host_uuid_filename}", self.HOST_UUID_HSUM)
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+ wait_for_console_pattern(self, prompt)
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+
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+ exec_command_and_wait_for_pattern(self,
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+ f"echo -n '{self.GUEST_UUID}' > {guest_uuid_path}", prompt)
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+ self.check_http_download(guest_uuid_path, self.GUEST_UUID_HSUM)
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+ wait_for_console_pattern(self, prompt)
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+
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+ self.vm.shutdown()
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+ vubr_proc.terminate()
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+ vubr_proc.wait()
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+
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+if __name__ == '__main__':
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+ LinuxKernelTest.main()