What VLAN configurations are supported for kdump?

Root Cause

Red Hat Enterprise Linux 9.

• The source code for kdump (kexec-tools-2.0.23-9_1.el9_0.x86_64 at the time of writing) which checks the VLAN configuration on the local system is listed below, wherein kdump explicitly reports to the console that VLAN over a bridged device is unsupported:

kdump_setup_vlan() {
    local _netdev=$1
    local _phydev
    local _netmac
    local _kdumpdev

    _phydev="$(awk '/^Device:/{print $2}' /proc/net/vlan/"$_netdev")"
    _netmac="$(kdump_get_mac_addr "$_phydev")"

    #Just support vlan over bond and team
    if kdump_is_bridge "$_phydev"; then
        derror "Vlan over bridge is not supported!"          <-----
        exit 1
    elif kdump_is_bond "$_phydev"; then
        (kdump_setup_bond "$_phydev" "$(get_nmcli_connection_apath_by_ifname "$_phydev")") || exit 1
        echo " vlan=$(kdump_setup_ifname "$_netdev"):$_phydev" > "${initdir}/etc/cmdline.d/43vlan.conf"
    else
        _kdumpdev="$(kdump_setup_ifname "$_phydev")"
        echo " vlan=$(kdump_setup_ifname "$_netdev"):$_kdumpdev ifname=$_kdumpdev:$_netmac" > "${initdir}/etc/cmdline.d/43vlan.conf"
    fi
}

Red Hat Enterprise Linux 8

• The source code for kdump (kexec-tools-2.0.20-46.el8_4.2.x86_64 at the time of writing) which checks the VLAN configuration on the local system is listed below, wherein kdump explicitly reports to the console that VLAN over a bridged device is unsupported:

  kdump_setup_vlan() {
      local _netdev=$1
      local _phydev="$(awk '/^Device:/{print $2}' /proc/net/vlan/"$_netdev")"
      local _netmac="$(kdump_get_mac_addr $_phydev)"
      local _kdumpdev
  
      #Just support vlan over bond and team
      if kdump_is_bridge "$_phydev"; then
          derror "Vlan over bridge is not supported!"            <-----
          exit 1
      elif kdump_is_bond "$_phydev"; then
          kdump_setup_bond "$_phydev"
          echo " vlan=$(kdump_setup_ifname $_netdev):$_phydev" > ${initdir}/etc/cmdline.d/43vlan.conf
      else
          _kdumpdev="$(kdump_setup_ifname $_phydev)"
          echo " vlan=$(kdump_setup_ifname $_netdev):$_kdumpdev ifname=$_kdumpdev:$_netmac" > ${initdir}/etc/cmdline.d/43vlan.conf
      fi
  }
  

Red Hat Enterprise Linux 7

• The source code for kdump (kexec-tools-2.0.15-21.el7_6.3.x86_64 at the time of writing) which checks the VLAN configuration on the local system is listed below, wherein kdump explicitly reports to the console that VLAN over a bridged device or over a team is unsupported:

  kdump_setup_vlan() {
      local _netdev=$1
      local _phydev="$(awk '/^Device:/{print $2}' /proc/net/vlan/"$_netdev")"
      local _netmac="$(kdump_get_mac_addr $_phydev)"
      local _kdumpdev
  
      #Just support vlan over bond, it is not easy
      #to support all other complex setup
      if kdump_is_bridge "$_phydev"; then
          derror "Vlan over bridge is not supported!"        <---
          exit 1
      elif kdump_is_team "$_phydev"; then
          derror "Vlan over team is not supported!"           <---
          exit 1
      elif kdump_is_bond "$_phydev"; then
          kdump_setup_bond "$_phydev"
          echo " vlan=$_netdev:$_phydev" > ${initdir}/etc/cmdline.d/43vlan.conf
      else
          _kdumpdev="$(kdump_setup_ifname $_phydev)"
          echo " vlan=$_netdev:$_kdumpdev ifname=$_kdumpdev:$_netmac" > ${initdir}/etc/cmdline.d/43vlan.conf
      fi
  }