RFC Bridging plan

Attached is the parser of this bridging plan. Bridge details if parsed from cmdline are written to /tmp/bridge.info for later use by network scripts with the following behavior. Any comments?

SYNTAX
======
bridge=<bridgename>:<ethname>
If bridge without parameters, assume bridge=br0:eth0

BASIC IDEA
==========
* When <ethname> would be configured by network scripts, instead create a bridge named <bridgename> then add <ethname> to that bridge.
* <bridgename> automatically inherits the MAC address of <ethname>. BOOTIF thus should be optionally workable.
* Then $netif becomes <bridgename> instead of <ethname> and all existing scripts process netroot mount via this new $netif instead of <ethname>.
* Try only the one specified <ethname> interface, do not try others. (I suppose trying others in the "bridge root=dhcp" case would be possible, but let's get the basics working first.)
* write-ifcfg.sh writes out both ifcfg-<bridgename> and ifcfg-<ethname> files for later use by NetworkManager.

BOOT EXAMPLE
============
ifconfig eth0 up
brctl addbr br0
brctl setfd br0 0
brctl addif br0 eth0
dhclient br0
ifconfig br0 <parameters>
mount -t nfs server:/path /sysroot
switch_root /sysroot

ifcfg-br0 example
=================
# Generated by dracut initrd
DEVICE=br0
TYPE=Bridge
ONBOOT=yes
BOOTPROTO=dhcp
STP=off
USERCTL=no

ifcfg-eth0 example
==================
# Generated by dracut initrd
TYPE=Ethernet
DEVICE=eth0
HWADDR=52:54:00:12:34:56
ONBOOT=yes
BRIDGE=br0
USERCTL=no

Warren Togami
[email protected]

From 329b0b77e7d63ebe2092111de31f471fd22a5b06 Mon Sep 17 00:00:00 2001
From: Warren Togami <[email protected]>
Date: Thu, 16 Jul 2009 00:09:07 -0400
Subject: [PATCH] Bridge parsing example

---
 modules.d/40network/check           |    2 +-
 modules.d/40network/install         |    3 +-
 modules.d/40network/parse-bridge.sh |   55 +++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100755 modules.d/40network/parse-bridge.sh

index 79a6d97..3d45030 100755
@@ -1,4 +1,4 @@
 #!/bin/sh
-which ip dhclient hostname >/dev/null 2>&1 || exit 1
+which ip dhclient hostname brctl >/dev/null 2>&1 || exit 1
 exit 255
 

index 0b76cbd..216d203 100755
@@ -1,5 +1,5 @@
 #!/bin/bash
-dracut_install ip dhclient hostname
+dracut_install ip dhclient hostname brctl
 # Include wired net drivers, excluding wireless
 for modname in $(find "/lib/modules/$kernel/kernel/drivers" -name '*.ko'); do
   if nm -uPA $modname | grep -q eth_type_trans; then

@@ -18,6 +18,7 @@ instmods ecb arc4
 inst_hook pre-udev 60 "$moddir/net-genrules.sh"
 inst_hook cmdline 91 "$moddir/dhcp-root.sh"
 inst_hook cmdline 99 "$moddir/parse-ip-opts.sh"
+inst_hook cmdline 98 "$moddir/parse-bridge.sh"
 inst_hook pre-pivot 10 "$moddir/kill-dhclient.sh"
 
 # TODO ifcfg config style is redhat specific, this should probably

1.6.2.5

I was under the impression that you could swizzle IP addresses from "real" userspace even if the root filesystem was mounted over the network.

That said, did you have a specific use case in mind?

Victor Lowther
RHCE# 805008539634727
LPIC-2# LPI000140019
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