network: do not rename other interfaces and document the ifname usage

We do not support renaming in the kernel namespace anymore (as udev does
that not anymore). So, if a user wants to use ifname, he has to rename
to a custom namespace. "eth[0-9]+" is not allowed anymore.

dracut.cmdline.7.asc

@@ -295,24 +295,51 @@ Network
 **ip=**_<interface>_:_{dhcp|on|any|dhcp6|auto6}_[:[_<mtu>_][:_<macaddr>_]]::
     This parameter can be specified multiple times.
 +
+=====================
 dhcp|on|any|dhcp6::: get ip from dhcp server on a specific interface
 auto6::: do IPv6 autoconfiguration
-<macaddr>::: optionally set <macaddr> on the <interface>
+<macaddr>::: optionally **set** <macaddr> on the <interface>. This
+cannot be used in conjunction with the **ifname** argument for the
+same <interface>.
+=====================
+
+[IMPORTANT]
+=====================
+It is recommended to either bind <interface> to a MAC with the **ifname**
+argument. Or use biosdevname to name your interfaces, which will then have names according to their hardware location.
+
+em<port>::: for embedded NICs
+p<slot>#<port>_<virtual instance>::: for cards in PCI slots
+=====================
 
 **ip=**_<client-IP>_:_<server-IP>_:_<gateway-IP>_:_<netmask>_:_<client_hostname>_:_<interface>_:_{none|off|dhcp|on|any|dhcp6|auto6|ibft}_[:[_<mtu>_][:_<macaddr>_]]::
     explicit network configuration. If you want do define a IPv6 address, put it
     in brackets (e.g. [2001:DB8::1]). This parameter can be specified multiple
     times.
 +
-<macaddr>::: optionally set <macaddr> on the <interface>
+=====================
+<macaddr>::: optionally **set** <macaddr> on the <interface>. This
+cannot be used in conjunction with the **ifname** argument for the
+same <interface>.
+=====================
+
+[IMPORTANT]
+=====================
+It is recommended to either bind <interface> to a MAC with the **ifname**
+argument. Or use biosdevname to name your interfaces, which will then have names according to their hardware location.
+
+em<port>::: for embedded NICs
+p<slot>#<port>_<virtual instance>::: for cards in PCI slots
+=====================
 
 **ifname=**_<interface>_:_<MAC>_::
-    Assign network device name <interface> (ie eth0) to the NIC with MAC <MAC>.
-    Note: If you use this option you _must_ specify an ifname= argument for all
-    interfaces used in ip= or fcoe= arguments. However, if the interface in
-    ip= or fcoe= is a bridge, bonding or vlan interface, you should specify
-    an ifname= for _each_ of its underlying interfaces. This parameter can be
-    specified multiple times.
+    Assign network device name <interface> (ie "bootnet") to the NIC with MAC <MAC>.
++
+[IMPORTANT]
+
+Do **not** use the default kernel naming scheme for the interface name,
+as it can conflict with the kernel names. So, don't use "eth[0-9]+" for the
+interface name. Better name it "bootnet" or "bluesocket".
 
 **bootdev=**_<interface>_::
     specify network interface to use routing and netroot information from.
@@ -430,8 +457,10 @@ FCoE
 **fcoe=**_<edd|interface|MAC>_:_{dcb|nodcb}_::
     Try to connect to a FCoE SAN through the NIC specified by _<interface>_ or
     _<MAC>_ or EDD settings. For the second argument, currently only nodcb is
-    supported. This parameter can be specified multiple times. Note: letters in
-    the MAC-address must be lowercase!
+    supported. This parameter can be specified multiple times.
++
+[NOTE]
+letters in the MAC-address must be lowercase!
 
 NBD
 ~~~

modules.d/40network/ifname-genrules.sh

@@ -15,9 +15,4 @@ command -v parse_ifname_opts >/dev/null || . /lib/net-lib.sh
         printf 'SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="%s", ATTR{type}=="1", NAME="%s"\n' "$ifname_mac" "$ifname_if"
     done
 
-    # Rename non named interfaces out of the way for named ones.
-    for p in $(getargs ifname=); do
-        parse_ifname_opts $p
-        printf 'SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="?*", ATTR{type}=="1", NAME!="?*", KERNEL=="%s", NAME="%%k-renamed"\n' "$ifname_if"
-    done
-} > /etc/udev/rules.d/50-ifname.rules
+} >> /etc/udev/rules.d/80-ifname.rules

modules.d/40network/net-genrules.sh

@@ -54,7 +54,7 @@ fix_bootif() {
 
     # Default: We don't know the interface to use, handle all
     else
-        printf 'SUBSYSTEM=="net", RUN+="%s"\n' "/sbin/initqueue --onetime $ifup" > /etc/udev/rules.d/61-default-net.rules
+        printf 'SUBSYSTEM=="net", RUN+="%s"\n' "/sbin/initqueue --onetime $ifup" > /etc/udev/rules.d/91-default-net.rules
     fi
 
-} > /etc/udev/rules.d/60-net.rules
+} > /etc/udev/rules.d/90-net.rules

modules.d/40network/net-lib.sh

@@ -304,4 +304,14 @@ parse_ifname_opts() {
             die "Invalid arguments for ifname="
             ;;
     esac
+
+    case $ifname_if in
+        eth[0-9]|eth[0-9][0-9]|eth[0-9][0-9][0-9]|eth[0-9][0-9][0-9][0-9])
+            warn "ifname=$ifname_if uses the kernel name space for interfaces"
+            warn "This can fail for multiple network interfaces and is discouraged!"
+            warn "Please use a custom name like \"netboot\" or \"bluesocket\""
+            warn "or use biosdevname and no ifname= at all."
+            ;;
+    esac
+
 }

modules.d/95fcoe/fcoe-genrules.sh

@@ -13,4 +13,4 @@
     else
         printf 'ACTION=="add", SUBSYSTEM=="net", NAME=="%s", RUN+="/sbin/initqueue --onetime --unique --name fcoe-up-$env{INTERFACE} /sbin/fcoe-up $env{INTERFACE} %s"\n' "$fcoe_interface" "$fcoe_dcb"
     fi
-} > /etc/udev/rules.d/60-fcoe.rules
+} > /etc/udev/rules.d/92-fcoe.rules