From 348ba69de1b0acfe24ce2a5b3e5f0ef6ef3fbf3a Mon Sep 17 00:00:00 2001
From: Michael Biebl <biebl@debian.org>
Date: Tue, 17 Sep 2013 22:01:54 +0200
Subject: [PATCH] Abort udev upgrade if devtmpfs support is missing

Add preinst check to abort udev upgrade if the currently running kernel
lacks devtmpfs support. Since udev 176, devtmpfs is mandatory as udev no
longer creates any device nodes itself. This only affects self-compiled
kernels which now need CONFIG_DEVTMPFS=y.  Closes: #722580
---
 debian/udev.preinst | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/debian/udev.preinst b/debian/udev.preinst
index 14c88eedb..ed6182bac 100644
--- a/debian/udev.preinst
+++ b/debian/udev.preinst
@@ -117,6 +117,12 @@ check_kernel_features() {
 
   fi
 
+  local missing_devtmpfs=0
+  if ! grep -q '[[:space:]]devtmpfs$' /proc/filesystems; then
+    missing_devtmpfs=1
+    abort_install=1
+  fi
+
   local sysfs_deprecated=0
   if [ -d /sys/class/mem/null -a ! -L /sys/class/mem/null ]; then
     sysfs_deprecated=1
@@ -135,6 +141,15 @@ the running kernel:
 END
   fi
 
+  if [ "$missing_devtmpfs" -eq 1 ]; then
+    cat <<END
+Since release 176, udev requires support for the following features in
+the running kernel:
+
+- devtmpfs         (CONFIG_DEVTMPFS)
+END
+  fi
+
   if [ "$sysfs_deprecated" -eq 1 ]; then
     db_input critical udev/sysfs_deprecated_incompatibility || true
   fi
@@ -203,7 +218,7 @@ check_version() {
   # $2 is non-empty when installing from the "config-files" state
   [ "$2" ] || return 0
 
-  if dpkg --compare-versions $2 lt 168-2; then
+  if dpkg --compare-versions $2 lt 204-4; then
     # these must be checked first to allow aborting before changing anything
     if chrooted; then
       echo 'Running in a chroot, skipping the kernel versions checks!'