[arch-projects] [initscripts][udev][RFC] first step towards removing load-modules.sh

[Tom Gundersen]

Hi guys,

This is in regards to FS#18421.

I am looking at ways to move our udev package closer to upstream. The
biggest difference is currently our load-modules.sh script which
filters out what modules to load. This adds significant overhead to
boot, so I think it is the first thing that should go.

The below patch generate a blacklist file at boot from rc.conf, which
should be linked to by a softlink in /etc/modprobe.d/. This allows
udev to figure out blacklisting by itself.

Once this is in initscripts and a similar patch is in mkinitcpio, then
we can ditch load-modules.sh.

One thing to note: the attached patch does "blacklist <module>" (which
allows modules to be pulled in as dependencies). We could also do
"install <module> /bin/false" (which has the same effect as deleting
the module altogether), if that is necessary. I chose to use blacklist
as it looks to be the recommended way.

Thoughts?

Cheers,

Tom





>From 56e6e5684d40b66d810a3d7d424b5aabec6d660e Mon Sep 17 00:00:00 2001
From: Tom Gundersen <teg at jklm.no>
Date: Mon, 9 May 2011 22:15:43 +0200
Subject: [PATCH] udev: generate blacklist on boot

udev will read /etc/modprobe.d/*.conf and blacklist all modules that
are listed as

blacklist <module>

We parse rc.conf at boot and generate such a .conf file. It cannot be
written to /etc this early, so we save it to /run. A symlink exists in
/etc to get the desired functionality.

While we are at it we also write the list of autoloaded. This is
useful in case we ever want to move to using
/etc/modules-load.d/*.conf for loading modules.

With this patch load-modules.sh can be removed from the udev package
without loss of functionality.

Original-idea-by: Benjamen Richer <br at waldteufel-online.net>
Based-on-patch-by: David Reisner <d at falconindy.com>
Signed-off-by: Tom Gundersen <teg at jklm.no>
---
 Makefile            |    4 +++-
 rc.gen-module-lists |   32 ++++++++++++++++++++++++++++++++
 rc.sysinit          |    3 +++
 3 files changed, 38 insertions(+), 1 deletions(-)
 create mode 100755 rc.gen-module-lists

diff --git a/Makefile b/Makefile
index d3a1824..dfb2ff0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 VER  := $(shell git describe)
-DIRS := /etc/rc.d /etc/conf.d /etc/rc.d/functions.d /etc/cron.hourly /sbin
+DIRS := /etc/rc.d /etc/conf.d /etc/rc.d/functions.d /etc/cron.hourly
/sbin /etc/modprobe.d /etc/module-load.d

 minilogd: minilogd.o

@@ -13,6 +13,8 @@ install: minilogd installdirs
 	install -m755 -t $(DESTDIR)/etc/cron.hourly adjtime
 	install -m755 -t $(DESTDIR)/etc/rc.d functions hwclock network netfs
 	install -m755 -t $(DESTDIR)/sbin minilogd rc
+	ln -s /run/initscripts/modules-blacklist.conf
$(DESTDIR)/etc/modprobe.d/arch-blacklist.conf
+	ln -s /run/initscripts/modules-load.conf
$(DESTDIR)/etc/modules-load.d/arch-modules.conf

 clean:
 	rm -f minilogd minilogd.o
diff --git a/rc.gen-module-lists b/rc.gen-module-lists
new file mode 100755
index 0000000..14f9619
--- /dev/null
+++ b/rc.gen-module-lists
@@ -0,0 +1,32 @@
+#!/bin/bash
+#
+# /etc/rc.gen-modules-list
+#
+
+. /etc/rc.conf
+
+declare -a modules blacklist
+for mod in "${MODULES[@]}"; do
+	case $mod in
+		!*) blacklist+=("${mod:1}") ;;
+		*) modules+=("$mod") ;;
+	esac
+done
+
+# create new module blacklist in /run/initscripts, there should be a
symlink in /etc/modprobe.d/ pointing here
+if [[ $blacklist ]]; then
+	/bin/mkdir -p /run/initscripts
+	echo "# Autogenerated from rc.conf at boot, do not edit" >
/run/initscripts/modules-blacklist.conf
+	(( ${#blacklist[@]} )) && printf 'blacklist %s\n' "${blacklist[@]}"
>> /run/initscripts/modules-blacklist.conf
+fi
+
+# create new module list in /run/initscripts, there should be a
symlink in /etc/modules-load.d/ pointing here
+if [[ $modules ]]; then
+	/bin/mkdir -p /run/initscripts
+	echo "# Autogenerated from rc.conf at boot, do not edit" >
/run/initscripts/modules-load.conf
+	printf '%s\n' "${modules[@]}" >> /run/initscripts/modules-load.conf
+fi
+
+unset blacklist modules
+
+# vim: set noet ts=2 sw=2:
diff --git a/rc.sysinit b/rc.sysinit
index 1521299..4e45d7c 100755
--- a/rc.sysinit
+++ b/rc.sysinit
@@ -83,6 +83,9 @@ if [[ $HWCLOCK_PARAMS ]]; then
 	fi
 fi

+# parse rc.conf and create the blacklist file for use by udev
+status "Creating UDev blacklist" /etc/rc.gen-module-lists
+
 status "Starting UDev Daemon" /sbin/udevd --daemon

 run_hook sysinit_udevlaunched
-- 
1.7.5.1