Committing the aufs2.1 patch by Shea Levy. His comments:

* My motivation for this patch is that kernels < 2.6.36 contain an
     e1000e that does not support the ethernet card that is part of the
     chipset for the second-generation Core-i Intel CPUs, so in order
     to have a more useful livecd I needed to get aufs working with a
     newer kernel, and 2.6.37 is the latest kernel with an official
     aufs release.
   * All sources are downloaded with fetchgit. This is because the aufs
     upstream doesn't provide release tarballs, they just add a tag to
     their git tree for an official release.
   * The make target for the aufs2.1 headers uses a Makefile in the
     kernel build directory that requires that unifdef be in the
     scripts/ subdirectory of the build directory. The way I've dealt
     with this here is by adding "make $makeFlags -C scripts unifdef"
     to the postBuild in the kernel builder. Since the builder is used
     by all kernel versions, this will require rebuilding every kernel
     and kernel-dependent package if the patch is accepted, so one
     alternative I thought of would be to create a fake kernel build
     directory where everything is symlinked to the real build
     directory except scripts/, which is first copied and then make
     unifdef is run before building aufs2.1. If that more complicated
     solution is preferred, or if anyone has ideas for another one, I
     can do that and submit a new patch.
   * The patch was tested by building a livecd ISO that uses it, then
     running the ISO from within virtualbox and installing aufs2.1-util
     from within the livecd environment.
   * The livecd was built using installation-cd-minimal.nix, with two
     changes to the Nixos tree:
        1. boot.kernelPackages = pkgs.linuxPackages_2_6_37 was added to
           profiles/minimal.nix
        2. config.boot.kernelPackages.aufs2 was changed to
           config.boot.kernelPackages.aufs2_1 in iso-image.nix
     I would have preferred to keep all changes within
     profiles/minimal.nix, but I couldn't figure out how to override
     iso-image.nix's definition of boot.extraModulePackages. Livecds
     that use an older kernel can't be built with this iso-image.nix,
     since we don't have aufs2.1 for them (just aufs2). If someone can
     point me to how I can override things set in iso-image.nix, I'd
     appreciate it.

make -C scripts unifdef compiles the unifdef application in the
scripts/ directory, and when Nix copies over the build tree to
$out/lib/modules/$version/build for kernel modules to reference, it
copies over all of scripts/ except the .o files. I can't speak for
other kernel versions, but at the least for 2.6.37.1 unifdef is not
built by default. If you look at the Makefile in scripts, unifdef is
listed  under a comment saying that the following programs are only
built on-demand.

svn path=/nixpkgs/trunk/; revision=26548

pkgs/os-specific/linux/aufs2.1-util/default.nix

@@ -0,0 +1,41 @@
+{ stdenv, fetchgit, kernel, aufs2_1 }:
+
+let version = "20110217"; in
+
+stdenv.mkDerivation {
+  name = "aufs2.1-util-${version}";
+
+  src = fetchgit {
+    url = "git://git.c3sl.ufpr.br/aufs/aufs2-util.git";
+    rev = "0f0cf3f2ae39906fd4b5376cdaa24e9fe64a03f4";
+    sha256 = "0fce5601b67efe8b5652a813ae612348bf4503aa71056cd31a5ed0406632e364";
+  };
+
+  buildInputs = [ aufs2_1 ];
+
+  makeFlags =
+    [ "KDIR=${kernel}/lib/modules/${kernel.version}/build"
+      "Install=install"
+      "DESTDIR=$(out)"
+    ];
+
+  postInstall =
+    ''
+      mv $out/usr/* $out
+      rmdir $out/usr
+
+      cp aufs.shlib $out/lib/
+
+      substituteInPlace $out/bin/aubrsync \
+        --replace /sbin/mount $out/sbin/mount \
+        --replace /usr/lib/aufs.shlib $out/lib/aufs.shlib
+    '';
+
+  meta = {
+    description = "Utilities for AUFS2.1";
+    homepage = http://aufs.sourceforge.net/;
+    maintainers = [ stdenv.lib.maintainers.eelco 
+                    stdenv.lib.maintainers.shlevy ];
+    platforms = stdenv.lib.platforms.linux;
+  };
+}

pkgs/os-specific/linux/aufs2.1/default.nix

@@ -0,0 +1,37 @@
+{ stdenv, kernel, fetchgit, perl }:
+
+assert kernel.features ? aufsBase;
+
+let version = "20110303"; in
+
+stdenv.mkDerivation {
+  name = "aufs2.1-${version}";
+
+  src = fetchgit {
+    url = "git://git.c3sl.ufpr.br/aufs/aufs2-standalone.git";
+    rev = "aceef6c84dbe5798bf46904252727b9588eafaf6";
+    sha256 = "50a8cb39af5fee82e88b65351cac52b6ab95a68c45e0a98da9fa1925b28f048d";
+  };
+
+  buildInputs = [ perl ];
+
+  makeFlags = "KDIR=${kernel}/lib/modules/${kernel.version}/build";
+
+  installPhase =
+    ''
+      ensureDir $out/lib/modules/${kernel.version}/misc
+      cp -v aufs.ko $out/lib/modules/${kernel.version}/misc
+
+      # Install the headers because aufs2.1-util requires them.
+      cp -av usr/include $out/
+    '';
+
+  meta = {
+    description = "Another Unionfs implementation for Linux (second generation)";
+    homepage = http://aufs.sourceforge.net/;
+    maintainers = [ stdenv.lib.maintainers.eelco
+                    stdenv.lib.maintainers.raskin
+                    stdenv.lib.maintainers.shlevy ];
+    platforms = stdenv.lib.platforms.linux;
+  };
+}

pkgs/os-specific/linux/kernel/aufs2.1-37.patch

@@ -0,0 +1,368 @@
+aufs2.1 base patch for linux-2.6.37
+
+diff --git a/fs/namei.c b/fs/namei.c
+index 4ff7ca5..a8c583f 100644
+--- a/fs/namei.c
++++ b/fs/namei.c
+@@ -1161,12 +1161,12 @@ out:
+  * needs parent already locked. Doesn't follow mounts.
+  * SMP-safe.
+  */
+-static struct dentry *lookup_hash(struct nameidata *nd)
++struct dentry *lookup_hash(struct nameidata *nd)
+ {
+ 	return __lookup_hash(&nd->last, nd->path.dentry, nd);
+ }
+ 
+-static int __lookup_one_len(const char *name, struct qstr *this,
++int __lookup_one_len(const char *name, struct qstr *this,
+ 		struct dentry *base, int len)
+ {
+ 	unsigned long hash;
+diff --git a/fs/splice.c b/fs/splice.c
+index ce2f025..ff0ae69 100644
+--- a/fs/splice.c
++++ b/fs/splice.c
+@@ -1092,8 +1092,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
+ /*
+  * Attempt to initiate a splice from pipe to file.
+  */
+-static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+-			   loff_t *ppos, size_t len, unsigned int flags)
++long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
++		    loff_t *ppos, size_t len, unsigned int flags)
+ {
+ 	ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
+ 				loff_t *, size_t, unsigned int);
+@@ -1120,9 +1120,9 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ /*
+  * Attempt to initiate a splice from a file to a pipe.
+  */
+-static long do_splice_to(struct file *in, loff_t *ppos,
+-			 struct pipe_inode_info *pipe, size_t len,
+-			 unsigned int flags)
++long do_splice_to(struct file *in, loff_t *ppos,
++		  struct pipe_inode_info *pipe, size_t len,
++		  unsigned int flags)
+ {
+ 	ssize_t (*splice_read)(struct file *, loff_t *,
+ 			       struct pipe_inode_info *, size_t, unsigned int);
+diff --git a/include/linux/namei.h b/include/linux/namei.h
+index 05b441d..91bc74e 100644
+--- a/include/linux/namei.h
++++ b/include/linux/namei.h
+@@ -73,6 +73,9 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
+ extern struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
+ 		int (*open)(struct inode *, struct file *));
+ 
++extern struct dentry *lookup_hash(struct nameidata *nd);
++extern int __lookup_one_len(const char *name, struct qstr *this,
++			    struct dentry *base, int len);
+ extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
+ 
+ extern int follow_down(struct path *);
+diff --git a/include/linux/splice.h b/include/linux/splice.h
+index 997c3b4..be9a153 100644
+--- a/include/linux/splice.h
++++ b/include/linux/splice.h
+@@ -89,4 +89,10 @@ extern int splice_grow_spd(struct pipe_inode_info *, struct splice_pipe_desc *);
+ extern void splice_shrink_spd(struct pipe_inode_info *,
+ 				struct splice_pipe_desc *);
+ 
++extern long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
++			   loff_t *ppos, size_t len, unsigned int flags);
++extern long do_splice_to(struct file *in, loff_t *ppos,
++			 struct pipe_inode_info *pipe, size_t len,
++			 unsigned int flags);
++
+ #endif
+aufs2.1 standalone patch for linux-2.6.37
+
+diff --git a/fs/file_table.c b/fs/file_table.c
+index c3dee38..f529e4d 100644
+--- a/fs/file_table.c
++++ b/fs/file_table.c
+@@ -393,6 +393,8 @@ void file_sb_list_del(struct file *file)
+ 	}
+ }
+ 
++EXPORT_SYMBOL(file_sb_list_del);
++
+ #ifdef CONFIG_SMP
+ 
+ /*
+diff --git a/fs/inode.c b/fs/inode.c
+index ae2727a..2c8071a 100644
+--- a/fs/inode.c
++++ b/fs/inode.c
+@@ -82,6 +82,7 @@ static struct hlist_head *inode_hashtable __read_mostly;
+  * the i_state of an inode while it is in use..
+  */
+ DEFINE_SPINLOCK(inode_lock);
++EXPORT_SYMBOL(inode_lock);
+ 
+ /*
+  * iprune_sem provides exclusion between the kswapd or try_to_free_pages
+diff --git a/fs/namei.c b/fs/namei.c
+index a8c583f..b020c45 100644
+--- a/fs/namei.c
++++ b/fs/namei.c
+@@ -347,6 +347,7 @@ int deny_write_access(struct file * file)
+ 
+ 	return 0;
+ }
++EXPORT_SYMBOL(deny_write_access);
+ 
+ /**
+  * path_get - get a reference to a path
+@@ -1165,6 +1166,7 @@ struct dentry *lookup_hash(struct nameidata *nd)
+ {
+ 	return __lookup_hash(&nd->last, nd->path.dentry, nd);
+ }
++EXPORT_SYMBOL(lookup_hash);
+ 
+ int __lookup_one_len(const char *name, struct qstr *this,
+ 		struct dentry *base, int len)
+@@ -1187,6 +1189,7 @@ int __lookup_one_len(const char *name, struct qstr *this,
+ 	this->hash = end_name_hash(hash);
+ 	return 0;
+ }
++EXPORT_SYMBOL(__lookup_one_len);
+ 
+ /**
+  * lookup_one_len - filesystem helper to lookup single pathname component
+diff --git a/fs/namespace.c b/fs/namespace.c
+index 3dbfc07..3998762 100644
+--- a/fs/namespace.c
++++ b/fs/namespace.c
+@@ -1321,6 +1321,7 @@ int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
+ 	}
+ 	return 0;
+ }
++EXPORT_SYMBOL(iterate_mounts);
+ 
+ static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end)
+ {
+diff --git a/fs/notify/group.c b/fs/notify/group.c
+index d309f38..f0e9568 100644
+--- a/fs/notify/group.c
++++ b/fs/notify/group.c
+@@ -22,6 +22,7 @@
+ #include <linux/srcu.h>
+ #include <linux/rculist.h>
+ #include <linux/wait.h>
++#include <linux/module.h>
+ 
+ #include <linux/fsnotify_backend.h>
+ #include "fsnotify.h"
+@@ -70,6 +71,7 @@ void fsnotify_put_group(struct fsnotify_group *group)
+ 	if (atomic_dec_and_test(&group->refcnt))
+ 		fsnotify_destroy_group(group);
+ }
++EXPORT_SYMBOL(fsnotify_put_group);
+ 
+ /*
+  * Create a new fsnotify_group and hold a reference for the group returned.
+@@ -102,3 +104,4 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
+ 
+ 	return group;
+ }
++EXPORT_SYMBOL(fsnotify_alloc_group);
+diff --git a/fs/notify/mark.c b/fs/notify/mark.c
+index 325185e..adede09 100644
+--- a/fs/notify/mark.c
++++ b/fs/notify/mark.c
+@@ -113,6 +113,7 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
+ 	if (atomic_dec_and_test(&mark->refcnt))
+ 		mark->free_mark(mark);
+ }
++EXPORT_SYMBOL(fsnotify_put_mark);
+ 
+ /*
+  * Any time a mark is getting freed we end up here.
+@@ -190,6 +191,7 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
+ 	if (unlikely(atomic_dec_and_test(&group->num_marks)))
+ 		fsnotify_final_destroy_group(group);
+ }
++EXPORT_SYMBOL(fsnotify_destroy_mark);
+ 
+ void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask)
+ {
+@@ -277,6 +279,7 @@ err:
+ 
+ 	return ret;
+ }
++EXPORT_SYMBOL(fsnotify_add_mark);
+ 
+ /*
+  * clear any marks in a group in which mark->flags & flags is true
+@@ -332,6 +335,7 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
+ 	atomic_set(&mark->refcnt, 1);
+ 	mark->free_mark = free_mark;
+ }
++EXPORT_SYMBOL(fsnotify_init_mark);
+ 
+ static int fsnotify_mark_destroy(void *ignored)
+ {
+diff --git a/fs/open.c b/fs/open.c
+index 4197b9e..912817a 100644
+--- a/fs/open.c
++++ b/fs/open.c
+@@ -60,6 +60,7 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
+ 	mutex_unlock(&dentry->d_inode->i_mutex);
+ 	return ret;
+ }
++EXPORT_SYMBOL(do_truncate);
+ 
+ static long do_sys_truncate(const char __user *pathname, loff_t length)
+ {
+diff --git a/fs/splice.c b/fs/splice.c
+index ff0ae69..1c9e9b0 100644
+--- a/fs/splice.c
++++ b/fs/splice.c
+@@ -1116,6 +1116,7 @@ long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ 
+ 	return splice_write(pipe, out, ppos, len, flags);
+ }
++EXPORT_SYMBOL(do_splice_from);
+ 
+ /*
+  * Attempt to initiate a splice from a file to a pipe.
+@@ -1142,6 +1143,7 @@ long do_splice_to(struct file *in, loff_t *ppos,
+ 
+ 	return splice_read(in, ppos, pipe, len, flags);
+ }
++EXPORT_SYMBOL(do_splice_to);
+ 
+ /**
+  * splice_direct_to_actor - splices data directly between two non-pipes
+diff --git a/security/commoncap.c b/security/commoncap.c
+index 64c2ed9..e58b5d8 100644
+--- a/security/commoncap.c
++++ b/security/commoncap.c
+@@ -929,3 +929,4 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
+ 	}
+ 	return ret;
+ }
++EXPORT_SYMBOL(cap_file_mmap);
+diff --git a/security/device_cgroup.c b/security/device_cgroup.c
+index 8d9c48f..29108aa 100644
+--- a/security/device_cgroup.c
++++ b/security/device_cgroup.c
+@@ -515,6 +515,7 @@ found:
+ 
+ 	return -EPERM;
+ }
++EXPORT_SYMBOL(devcgroup_inode_permission);
+ 
+ int devcgroup_inode_mknod(int mode, dev_t dev)
+ {
+diff --git a/security/security.c b/security/security.c
+index 1b798d3..3b7d2ca 100644
+--- a/security/security.c
++++ b/security/security.c
+@@ -360,6 +360,7 @@ int security_path_mkdir(struct path *dir, struct dentry *dentry, int mode)
+ 		return 0;
+ 	return security_ops->path_mkdir(dir, dentry, mode);
+ }
++EXPORT_SYMBOL(security_path_mkdir);
+ 
+ int security_path_rmdir(struct path *dir, struct dentry *dentry)
+ {
+@@ -367,6 +368,7 @@ int security_path_rmdir(struct path *dir, struct dentry *dentry)
+ 		return 0;
+ 	return security_ops->path_rmdir(dir, dentry);
+ }
++EXPORT_SYMBOL(security_path_rmdir);
+ 
+ int security_path_unlink(struct path *dir, struct dentry *dentry)
+ {
+@@ -374,6 +376,7 @@ int security_path_unlink(struct path *dir, struct dentry *dentry)
+ 		return 0;
+ 	return security_ops->path_unlink(dir, dentry);
+ }
++EXPORT_SYMBOL(security_path_unlink);
+ 
+ int security_path_symlink(struct path *dir, struct dentry *dentry,
+ 			  const char *old_name)
+@@ -382,6 +385,7 @@ int security_path_symlink(struct path *dir, struct dentry *dentry,
+ 		return 0;
+ 	return security_ops->path_symlink(dir, dentry, old_name);
+ }
++EXPORT_SYMBOL(security_path_symlink);
+ 
+ int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+ 		       struct dentry *new_dentry)
+@@ -390,6 +394,7 @@ int security_path_link(struct dentry *old_dentry, struct path *new_dir,
+ 		return 0;
+ 	return security_ops->path_link(old_dentry, new_dir, new_dentry);
+ }
++EXPORT_SYMBOL(security_path_link);
+ 
+ int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+ 			 struct path *new_dir, struct dentry *new_dentry)
+@@ -400,6 +405,7 @@ int security_path_rename(struct path *old_dir, struct dentry *old_dentry,
+ 	return security_ops->path_rename(old_dir, old_dentry, new_dir,
+ 					 new_dentry);
+ }
++EXPORT_SYMBOL(security_path_rename);
+ 
+ int security_path_truncate(struct path *path)
+ {
+@@ -407,6 +413,7 @@ int security_path_truncate(struct path *path)
+ 		return 0;
+ 	return security_ops->path_truncate(path);
+ }
++EXPORT_SYMBOL(security_path_truncate);
+ 
+ int security_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
+ 			mode_t mode)
+@@ -415,6 +422,7 @@ int security_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
+ 		return 0;
+ 	return security_ops->path_chmod(dentry, mnt, mode);
+ }
++EXPORT_SYMBOL(security_path_chmod);
+ 
+ int security_path_chown(struct path *path, uid_t uid, gid_t gid)
+ {
+@@ -422,6 +430,7 @@ int security_path_chown(struct path *path, uid_t uid, gid_t gid)
+ 		return 0;
+ 	return security_ops->path_chown(path, uid, gid);
+ }
++EXPORT_SYMBOL(security_path_chown);
+ 
+ int security_path_chroot(struct path *path)
+ {
+@@ -498,6 +507,7 @@ int security_inode_readlink(struct dentry *dentry)
+ 		return 0;
+ 	return security_ops->inode_readlink(dentry);
+ }
++EXPORT_SYMBOL(security_inode_readlink);
+ 
+ int security_inode_follow_link(struct dentry *dentry, struct nameidata *nd)
+ {
+@@ -512,6 +522,7 @@ int security_inode_permission(struct inode *inode, int mask)
+ 		return 0;
+ 	return security_ops->inode_permission(inode, mask);
+ }
++EXPORT_SYMBOL(security_inode_permission);
+ 
+ int security_inode_setattr(struct dentry *dentry, struct iattr *attr)
+ {
+@@ -611,6 +622,7 @@ int security_file_permission(struct file *file, int mask)
+ 
+ 	return fsnotify_perm(file, mask);
+ }
++EXPORT_SYMBOL(security_file_permission);
+ 
+ int security_file_alloc(struct file *file)
+ {
+@@ -638,6 +650,7 @@ int security_file_mmap(struct file *file, unsigned long reqprot,
+ 		return ret;
+ 	return ima_file_mmap(file, prot);
+ }
++EXPORT_SYMBOL(security_file_mmap);
+ 
+ int security_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
+ 			    unsigned long prot)
+

pkgs/os-specific/linux/kernel/builder.sh

@@ -50,6 +50,7 @@ postBuild() {
     # After the builder did a 'make all' (kernel + modules)
     # we force building the target asked: bzImage/zImage/uImage/...
     make $makeFlags $kernelTarget
+    make $makeFlags -C scripts unifdef
 }
 
 installPhase() {

pkgs/os-specific/linux/kernel/patches.nix

@@ -202,6 +202,15 @@ in
       features.aufsBase = true;
     };
 
+  aufs2_1_2_6_37 =
+    { # From http://git.c3sl.ufpr.br/gitweb?p=aufs/aufs2-standalone.git;a=tree;h=refs/heads/aufs2.1-37;hb=refs/heads/aufs2.1-37
+      # Note that this merely the patch needed to build AUFS2.1 as a
+      # standalone package.
+      name = "aufs2.1";
+      patch = ./aufs2.1-37.patch;
+      features.aufsBase = true;
+    };
+
   # Increase the timeout on CIFS requests from 15 to 120 seconds to
   # make CIFS more resilient to high load on the CIFS server.
   cifs_timeout =

pkgs/top-level/all-packages.nix

@@ -5067,7 +5067,7 @@ let
     kernelPatches =
       [ kernelPatches.fbcondecor_2_6_37
         kernelPatches.sec_perm_2_6_24
-        #kernelPatches.aufs2_2_6_35
+        kernelPatches.aufs2_1_2_6_37
         #kernelPatches.mips_restart_2_6_36
       ];
   };
@@ -5106,8 +5106,12 @@ let
 
     aufs2 = callPackage ../os-specific/linux/aufs2 { };
 
+    aufs2_1 = callPackage ../os-specific/linux/aufs2.1 { };
+
     aufs2_util = callPackage ../os-specific/linux/aufs2-util { };
 
+    aufs2_1_util = callPackage ../os-specific/linux/aufs2.1-util { };
+
     blcr = callPackage ../os-specific/linux/blcr {
       #libtool = libtool_1_5; # libtool 2 causes a fork bomb
     };