Testsuite: T3871: change testcase to use multiple NIC drivers

Extend testcase to use multiple differen virtual NIC drivers to also see if
they are always placed in the same order - given my ascending MAC addresses.

Author: c-po

scripts/check-qemu-install

@@ -82,6 +82,9 @@ tpm_folder = '/tmp/vyos_tpm_test'
 tpm_sock = f'{tpm_folder}/swtpm-sock'
 qemu_name = 'VyOS-QEMU'
 
+# RFC7042 section 2.1.2 MAC addresses used for documentation
+macbase = '00:00:5E:00:53'
+
 test_timeout = 5 *3600 # 5 hours (in seconds) to complete individual testcases
 
 op_mode_prompt = r'vyos@vyos:~\$'
@@ -268,9 +271,6 @@ def get_qemu_cmd(name, enable_uefi, disk_img, raid=None, iso_img=None, tpm=False
             else:
                 nested_cdrom = f'{nested_cdrom} -device ide-cd,bus=achi0.1,{drive_settings}'
 
-    # RFC7042 section 2.1.2 MAC addresses used for documentation
-    macbase = '00:00:5E:00:53'
-
     # Set QEmu disk image format - this differs if VyOS was installed via smoketest
     # or we use an already ewxisting image
     disk_format = 'qcow2' if args.disk.endswith('.qcow2') else 'raw'
@@ -290,10 +290,10 @@ def get_qemu_cmd(name, enable_uefi, disk_img, raid=None, iso_img=None, tpm=False
         -netdev user,id=n1 -device virtio-net-pci,netdev=n1,mac={macbase}:01,romfile="",host_mtu=1500 \
         -netdev user,id=n2 -device virtio-net-pci,netdev=n2,mac={macbase}:02,romfile="",host_mtu=1500 \
         -netdev user,id=n3 -device virtio-net-pci,netdev=n3,mac={macbase}:03,romfile="",host_mtu=1500 \
-        -netdev user,id=n4 -device virtio-net-pci,netdev=n4,mac={macbase}:04,romfile="" \
-        -netdev user,id=n5 -device virtio-net-pci,netdev=n5,mac={macbase}:05,romfile="" \
-        -netdev user,id=n6 -device virtio-net-pci,netdev=n6,mac={macbase}:06,romfile="" \
-        -netdev user,id=n7 -device virtio-net-pci,netdev=n7,mac={macbase}:07,romfile="" \
+        -netdev user,id=n4 -device e1000e,netdev=n4,mac={macbase}:04,romfile="" \
+        -netdev user,id=n5 -device e1000e,netdev=n5,mac={macbase}:05,romfile="" \
+        -netdev user,id=n6 -device vmxnet3,netdev=n6,mac={macbase}:06,romfile="" \
+        -netdev user,id=n7 -device vmxnet3,netdev=n7,mac={macbase}:07,romfile="" \
         -device virtio-scsi-pci,id=scsi0 \
         {cdrom}{nested_cdrom} \
         -drive format={disk_format},file={disk_img},if=none,media=disk,id=drive-hd1,readonly=off \
@@ -687,6 +687,31 @@ def basic_cli_tests(c):
     c.expect(f'set console_type="{console_type}"')
     c.expect(op_mode_prompt)
 
+def verify_eth_mac_mapping(c, log):
+    """ NICs are attached with a mix of drivers (virtio/e1000e/vmxnet3, see
+        get_qemu_cmd()) to cover different naming schemes. Regardless of
+        driver, udev must always enumerate them in ascending order: eth0
+        carries mac0, eth1 mac1, ... up to eth7 mac7 - never scrambled. """
+    log.info('Verify eth0..eth7 are enumerated in ascending MAC order')
+    c.sendline('ip -json link show | jq -r \'.[] | select(.ifname|test("^eth[0-9]+$")) | "\(.ifname) \(.address)"\'')
+    c.expect(op_mode_prompt)
+    lines = [l.strip() for l in c.before.decode(errors='replace').splitlines() if l.strip()]
+
+    macs = {}
+    for line in lines:
+        parts = line.split()
+        if len(parts) == 2 and re.fullmatch(r'eth\d+', parts[0]):
+            macs[parts[0]] = parts[1].lower()
+
+    for i in range(8):
+        ifname = f'eth{i}'
+        expected_mac = f'{macbase}:{i:02x}'.lower()
+        if ifname not in macs:
+            raise Exception(f'Interface {ifname} not found on installed system')
+        if macs[ifname] != expected_mac:
+            raise Exception(f'Interface {ifname} has MAC {macs[ifname]}, expected {expected_mac} - naming race?')
+    log.info('eth0..eth7 MAC mapping verified')
+
 def _image_update_cli_sequence(c, log, new_image_name, server_bind_host='127.0.0.1', use_vrf=False):
     """One add-system-image/delete cycle for nested ISO over HTTP (optional Linux VRF + VyOS vrf arg)."""
     url = f'http://{server_bind_host}:{NESTED_HTTP_SERV_PORT}/{NESTED_INNER_ISO_NAME}'
@@ -1067,6 +1092,11 @@ try:
     log.info('Basic CLI configuration mode test')
     basic_cli_tests(c)
 
+    #################################################
+    # Verify NIC driver mix did not scramble interface naming
+    #################################################
+    verify_eth_mac_mapping(c, log)
+
     #################################################
     # Verify /etc/os-release via lsb_release
     #################################################