diff --git a/pkgs/os-specific/linux/kernel/builder.sh b/pkgs/os-specific/linux/kernel/builder.sh
index f850514dcb77..336d11d9ac1b 100644
--- a/pkgs/os-specific/linux/kernel/builder.sh
+++ b/pkgs/os-specific/linux/kernel/builder.sh
@@ -3,61 +3,69 @@ source $stdenv/setup
 
 configurePhase=configurePhase
 configurePhase() {
-	export INSTALL_PATH=$out
-	export INSTALL_MOD_PATH=$out
+    export INSTALL_PATH=$out
+    export INSTALL_MOD_PATH=$out
 
-	cp $config .config
-        chmod u+w .config
+    cp $config .config
+    chmod u+w .config
 
-        echo "$extraConfig" >> .config
+    echo "$extraConfig" >> .config
 
-        #substituteInPlace scripts/kconfig/lxdialog/check-lxdialog.sh \
-        #    --replace /usr /no-such-path
+    #substituteInPlace scripts/kconfig/lxdialog/check-lxdialog.sh \
+    #    --replace /usr /no-such-path
 
-        # Necessary until NIXPKGS-38 is fixed:
-        echo "#! $SHELL" > scripts/kconfig/lxdialog/check-lxdialog.sh
-        chmod +x scripts/kconfig/lxdialog/check-lxdialog.sh
-        
-        make oldconfig
-}
-
-
-buildPhase=buildPhase
-buildPhase() {
-	make
+    # Necessary until NIXPKGS-38 is fixed:
+    echo "#! $SHELL" > scripts/kconfig/lxdialog/check-lxdialog.sh
+    chmod +x scripts/kconfig/lxdialog/check-lxdialog.sh
+    
+    make oldconfig \
+        $makeFlags "${makeFlagsArray[@]}"
 }
 
 
 installPhase=installPhase
 installPhase() {
 
-	ensureDir $out
+    ensureDir $out
 
-        # Copy the bzImage and System.map.
-        cp System.map $out
+    # Copy the bzImage and System.map.
+    cp System.map $out
+    if test "$arch" = um; then
+        ensureDir $out/bin
+        cp linux $out/bin
+    else
         cp arch/$arch/boot/bzImage $out/vmlinuz
+    fi
 
-        # Install the modules in $out/lib/modules with matching paths
-        # in modules.dep (i.e., refererring to $out/lib/modules, not
-        # /lib/modules).  The depmod_opts= is to prevent the kernel
-        # from passing `-b PATH' to depmod.
-        export MODULE_DIR=$out/lib/modules/
-	make modules_install DEPMOD=$module_init_tools/sbin/depmod depmod_opts=
+    # Install the modules in $out/lib/modules with matching paths
+    # in modules.dep (i.e., refererring to $out/lib/modules, not
+    # /lib/modules).  The depmod_opts= is to prevent the kernel
+    # from passing `-b PATH' to depmod.
+    export MODULE_DIR=$out/lib/modules/
+    make modules_install \
+        DEPMOD=$module_init_tools/sbin/depmod depmod_opts= \
+        $makeFlags "${makeFlagsArray[@]}" \
+        $installFlags "${installFlagsArray[@]}"
 
-        # Strip the kernel modules.
-        echo "Stripping kernel modules..."
-        find $out -name "*.ko" -print0 | xargs -0 strip -S
+    # Strip the kernel modules.
+    echo "Stripping kernel modules..."
+    find $out -name "*.ko" -print0 | xargs -0 strip -S
 
-        # move this to install later on
-        # largely copied from early FC3 kernel spec files
-        version=$(cd $out/lib/modules && ls -d *)
+    # move this to install later on
+    # largely copied from early FC3 kernel spec files
+    version=$(cd $out/lib/modules && ls -d *)
 
-        # remove symlinks and create directories
-        rm -f $out/lib/modules/$version/build
-        rm -f $out/lib/modules/$version/source
-        mkdir $out/lib/modules/$version/build
-        ln -s $out/lib/modules/$version/build $out/lib/modules/$version/source
+    # remove symlinks and create directories
+    rm -f $out/lib/modules/$version/build
+    rm -f $out/lib/modules/$version/source
+    mkdir $out/lib/modules/$version/build
+
+    # copy config
+    cp .config $out/lib/modules/$version/build/.config
+
+    if test "$arch" != um; then
         # copy all Makefiles and Kconfig files
+        ln -s $out/lib/modules/$version/build $out/lib/modules/$version/source
         cp --parents `find  -type f -name Makefile -o -name "Kconfig*"` $out/lib/modules/$version/build
         cp Module.symvers $out/lib/modules/$version/build
 
@@ -66,11 +74,7 @@ installPhase() {
         rm -rf $out/lib/modules/$version/build/scripts
         rm -rf $out/lib/modules/$version/build/include
 
-        # copy config
-	cp .config $out/lib/modules/$version/build/.config
-
         # copy architecture dependent files
-
         cp -a arch/$arch/scripts $out/lib/modules/$version/build || true
         cp -a arch/$arch/*lds $out/lib/modules/$version/build || true
         cp -a arch/$arch/Makefile.cpu $out/lib/modules/$version/build/arch/$arch || true
@@ -87,6 +91,7 @@ installPhase() {
         cp -a acpi config linux math-emu media net pcmcia rxrpc scsi sound video asm asm-generic $out/lib/modules/$version/build/include
         cp -a `readlink asm` $out/lib/modules/$version/build/include
         cd ..
+    fi
 }
 
 
diff --git a/pkgs/os-specific/linux/kernel/config-2.6.20-uml b/pkgs/os-specific/linux/kernel/config-2.6.20-uml
new file mode 100644
index 000000000000..1466a699a725
--- /dev/null
+++ b/pkgs/os-specific/linux/kernel/config-2.6.20-uml
@@ -0,0 +1,578 @@
+#
+# Automatically generated make config: don't edit
+# Linux kernel version: 2.6.20.4
+# Tue Mar 27 12:33:08 2007
+#
+CONFIG_DEFCONFIG_LIST="arch/$ARCH/defconfig"
+CONFIG_GENERIC_HARDIRQS=y
+CONFIG_UML=y
+CONFIG_MMU=y
+# CONFIG_TRACE_IRQFLAGS_SUPPORT is not set
+CONFIG_LOCKDEP_SUPPORT=y
+CONFIG_STACKTRACE_SUPPORT=y
+CONFIG_GENERIC_CALIBRATE_DELAY=y
+CONFIG_GENERIC_BUG=y
+CONFIG_IRQ_RELEASE_METHOD=y
+
+#
+# UML-specific options
+#
+# CONFIG_STATIC_LINK is not set
+CONFIG_MODE_SKAS=y
+
+#
+# Host processor type and features
+#
+# CONFIG_M386 is not set
+# CONFIG_M486 is not set
+# CONFIG_M586 is not set
+# CONFIG_M586TSC is not set
+# CONFIG_M586MMX is not set
+CONFIG_M686=y
+# CONFIG_MPENTIUMII is not set
+# CONFIG_MPENTIUMIII is not set
+# CONFIG_MPENTIUMM is not set
+# CONFIG_MCORE2 is not set
+# CONFIG_MPENTIUM4 is not set
+# CONFIG_MK6 is not set
+# CONFIG_MK7 is not set
+# CONFIG_MK8 is not set
+# CONFIG_MCRUSOE is not set
+# CONFIG_MEFFICEON is not set
+# CONFIG_MWINCHIPC6 is not set
+# CONFIG_MWINCHIP2 is not set
+# CONFIG_MWINCHIP3D is not set
+# CONFIG_MGEODEGX1 is not set
+# CONFIG_MGEODE_LX is not set
+# CONFIG_MCYRIXIII is not set
+# CONFIG_MVIAC3_2 is not set
+CONFIG_X86_GENERIC=y
+CONFIG_X86_CMPXCHG=y
+CONFIG_X86_XADD=y
+CONFIG_X86_L1_CACHE_SHIFT=7
+CONFIG_RWSEM_XCHGADD_ALGORITHM=y
+# CONFIG_ARCH_HAS_ILOG2_U32 is not set
+# CONFIG_ARCH_HAS_ILOG2_U64 is not set
+CONFIG_X86_PPRO_FENCE=y
+CONFIG_X86_WP_WORKS_OK=y
+CONFIG_X86_INVLPG=y
+CONFIG_X86_BSWAP=y
+CONFIG_X86_POPAD_OK=y
+CONFIG_X86_CMPXCHG64=y
+CONFIG_X86_GOOD_APIC=y
+CONFIG_X86_INTEL_USERCOPY=y
+CONFIG_X86_USE_PPRO_CHECKSUM=y
+CONFIG_X86_TSC=y
+CONFIG_UML_X86=y
+# CONFIG_64BIT is not set
+CONFIG_SEMAPHORE_SLEEPERS=y
+CONFIG_HOST_VMSPLIT_3G=y
+# CONFIG_HOST_VMSPLIT_3G_OPT is not set
+# CONFIG_HOST_VMSPLIT_2G is not set
+# CONFIG_HOST_VMSPLIT_1G is not set
+CONFIG_TOP_ADDR=0xC0000000
+# CONFIG_3_LEVEL_PGTABLES is not set
+CONFIG_STUB_CODE=0xbfffe000
+CONFIG_STUB_DATA=0xbffff000
+CONFIG_STUB_START=0xbfffe000
+CONFIG_ARCH_HAS_SC_SIGNALS=y
+CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA=y
+CONFIG_GENERIC_HWEIGHT=y
+CONFIG_SELECT_MEMORY_MODEL=y
+CONFIG_FLATMEM_MANUAL=y
+# CONFIG_DISCONTIGMEM_MANUAL is not set
+# CONFIG_SPARSEMEM_MANUAL is not set
+CONFIG_FLATMEM=y
+CONFIG_FLAT_NODE_MEM_MAP=y
+# CONFIG_SPARSEMEM_STATIC is not set
+CONFIG_SPLIT_PTLOCK_CPUS=4
+# CONFIG_RESOURCES_64BIT is not set
+CONFIG_LD_SCRIPT_DYN=y
+CONFIG_NET=y
+CONFIG_BINFMT_ELF=y
+CONFIG_BINFMT_MISC=m
+CONFIG_HOSTFS=y
+# CONFIG_HPPFS is not set
+CONFIG_MCONSOLE=y
+# CONFIG_MAGIC_SYSRQ is not set
+CONFIG_NEST_LEVEL=0
+# CONFIG_HIGHMEM is not set
+CONFIG_KERNEL_STACK_ORDER=2
+CONFIG_UML_REAL_TIME_CLOCK=y
+
+#
+# Code maturity level options
+#
+CONFIG_EXPERIMENTAL=y
+CONFIG_BROKEN_ON_SMP=y
+CONFIG_INIT_ENV_ARG_LIMIT=128
+
+#
+# General setup
+#
+CONFIG_LOCALVERSION=""
+CONFIG_LOCALVERSION_AUTO=y
+CONFIG_SWAP=y
+CONFIG_SYSVIPC=y
+# CONFIG_IPC_NS is not set
+CONFIG_POSIX_MQUEUE=y
+CONFIG_BSD_PROCESS_ACCT=y
+# CONFIG_BSD_PROCESS_ACCT_V3 is not set
+# CONFIG_TASKSTATS is not set
+# CONFIG_UTS_NS is not set
+# CONFIG_AUDIT is not set
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_SYSFS_DEPRECATED=y
+# CONFIG_RELAY is not set
+CONFIG_INITRAMFS_SOURCE=""
+CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+CONFIG_SYSCTL=y
+# CONFIG_EMBEDDED is not set
+CONFIG_UID16=y
+CONFIG_SYSCTL_SYSCALL=y
+CONFIG_KALLSYMS=y
+# CONFIG_KALLSYMS_ALL is not set
+CONFIG_KALLSYMS_EXTRA_PASS=y
+CONFIG_HOTPLUG=y
+CONFIG_PRINTK=y
+CONFIG_BUG=y
+CONFIG_ELF_CORE=y
+CONFIG_BASE_FULL=y
+CONFIG_FUTEX=y
+CONFIG_EPOLL=y
+CONFIG_SHMEM=y
+CONFIG_SLAB=y
+CONFIG_VM_EVENT_COUNTERS=y
+CONFIG_RT_MUTEXES=y
+# CONFIG_TINY_SHMEM is not set
+CONFIG_BASE_SMALL=0
+# CONFIG_SLOB is not set
+
+#
+# Loadable module support
+#
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+# CONFIG_MODULE_FORCE_UNLOAD is not set
+# CONFIG_MODVERSIONS is not set
+# CONFIG_MODULE_SRCVERSION_ALL is not set
+CONFIG_KMOD=y
+
+#
+# Block layer
+#
+CONFIG_BLOCK=y
+# CONFIG_LBD is not set
+# CONFIG_BLK_DEV_IO_TRACE is not set
+# CONFIG_LSF is not set
+
+#
+# IO Schedulers
+#
+CONFIG_IOSCHED_NOOP=y
+CONFIG_IOSCHED_AS=y
+CONFIG_IOSCHED_DEADLINE=y
+CONFIG_IOSCHED_CFQ=y
+CONFIG_DEFAULT_AS=y
+# CONFIG_DEFAULT_DEADLINE is not set
+# CONFIG_DEFAULT_CFQ is not set
+# CONFIG_DEFAULT_NOOP is not set
+CONFIG_DEFAULT_IOSCHED="anticipatory"
+
+#
+# Block devices
+#
+CONFIG_BLK_DEV_UBD=y
+# CONFIG_BLK_DEV_UBD_SYNC is not set
+CONFIG_BLK_DEV_COW_COMMON=y
+# CONFIG_MMAPPER is not set
+CONFIG_BLK_DEV_LOOP=m
+# CONFIG_BLK_DEV_CRYPTOLOOP is not set
+CONFIG_BLK_DEV_NBD=m
+# CONFIG_BLK_DEV_RAM is not set
+# CONFIG_BLK_DEV_INITRD is not set
+# CONFIG_ATA_OVER_ETH is not set
+
+#
+# Character Devices
+#
+CONFIG_STDERR_CONSOLE=y
+CONFIG_STDIO_CONSOLE=y
+CONFIG_SSL=y
+CONFIG_NULL_CHAN=y
+CONFIG_PORT_CHAN=y
+CONFIG_PTY_CHAN=y
+CONFIG_TTY_CHAN=y
+CONFIG_XTERM_CHAN=y
+# CONFIG_NOCONFIG_CHAN is not set
+CONFIG_CON_ZERO_CHAN="fd:0,fd:1"
+CONFIG_CON_CHAN="xterm"
+CONFIG_SSL_CHAN="pty"
+CONFIG_UNIX98_PTYS=y
+CONFIG_LEGACY_PTYS=y
+CONFIG_LEGACY_PTY_COUNT=256
+# CONFIG_WATCHDOG is not set
+CONFIG_UML_SOUND=m
+CONFIG_SOUND=m
+CONFIG_HOSTAUDIO=m
+# CONFIG_HW_RANDOM is not set
+CONFIG_UML_RANDOM=y
+
+#
+# Generic Driver Options
+#
+CONFIG_STANDALONE=y
+CONFIG_PREVENT_FIRMWARE_BUILD=y
+# CONFIG_FW_LOADER is not set
+# CONFIG_DEBUG_DRIVER is not set
+# CONFIG_SYS_HYPERVISOR is not set
+
+#
+# Networking
+#
+
+#
+# Networking options
+#
+# CONFIG_NETDEBUG is not set
+CONFIG_PACKET=y
+CONFIG_PACKET_MMAP=y
+CONFIG_UNIX=y
+CONFIG_XFRM=y
+# CONFIG_XFRM_USER is not set
+# CONFIG_XFRM_SUB_POLICY is not set
+# CONFIG_NET_KEY is not set
+CONFIG_INET=y
+# CONFIG_IP_MULTICAST is not set
+# CONFIG_IP_ADVANCED_ROUTER is not set
+CONFIG_IP_FIB_HASH=y
+# CONFIG_IP_PNP is not set
+# CONFIG_NET_IPIP is not set
+# CONFIG_NET_IPGRE is not set
+# CONFIG_ARPD is not set
+# CONFIG_SYN_COOKIES is not set
+# CONFIG_INET_AH is not set
+# CONFIG_INET_ESP is not set
+# CONFIG_INET_IPCOMP is not set
+# CONFIG_INET_XFRM_TUNNEL is not set
+# CONFIG_INET_TUNNEL is not set
+CONFIG_INET_XFRM_MODE_TRANSPORT=y
+CONFIG_INET_XFRM_MODE_TUNNEL=y
+CONFIG_INET_XFRM_MODE_BEET=y
+CONFIG_INET_DIAG=y
+CONFIG_INET_TCP_DIAG=y
+# CONFIG_TCP_CONG_ADVANCED is not set
+CONFIG_TCP_CONG_CUBIC=y
+CONFIG_DEFAULT_TCP_CONG="cubic"
+# CONFIG_TCP_MD5SIG is not set
+# CONFIG_IPV6 is not set
+# CONFIG_INET6_XFRM_TUNNEL is not set
+# CONFIG_INET6_TUNNEL is not set
+# CONFIG_NETWORK_SECMARK is not set
+# CONFIG_NETFILTER is not set
+
+#
+# DCCP Configuration (EXPERIMENTAL)
+#
+# CONFIG_IP_DCCP is not set
+
+#
+# SCTP Configuration (EXPERIMENTAL)
+#
+# CONFIG_IP_SCTP is not set
+
+#
+# TIPC Configuration (EXPERIMENTAL)
+#
+# CONFIG_TIPC is not set
+# CONFIG_ATM is not set
+# CONFIG_BRIDGE is not set
+# CONFIG_VLAN_8021Q is not set
+# CONFIG_DECNET is not set
+# CONFIG_LLC2 is not set
+# CONFIG_IPX is not set
+# CONFIG_ATALK is not set
+# CONFIG_X25 is not set
+# CONFIG_LAPB is not set
+# CONFIG_ECONET is not set
+# CONFIG_WAN_ROUTER is not set
+
+#
+# QoS and/or fair queueing
+#
+# CONFIG_NET_SCHED is not set
+
+#
+# Network testing
+#
+# CONFIG_NET_PKTGEN is not set
+# CONFIG_HAMRADIO is not set
+# CONFIG_IRDA is not set
+# CONFIG_BT is not set
+# CONFIG_IEEE80211 is not set
+
+#
+# UML Network Devices
+#
+CONFIG_UML_NET=y
+CONFIG_UML_NET_ETHERTAP=y
+CONFIG_UML_NET_TUNTAP=y
+CONFIG_UML_NET_SLIP=y
+CONFIG_UML_NET_DAEMON=y
+CONFIG_UML_NET_MCAST=y
+# CONFIG_UML_NET_PCAP is not set
+CONFIG_UML_NET_SLIRP=y
+
+#
+# Network device support
+#
+CONFIG_NETDEVICES=y
+CONFIG_DUMMY=m
+# CONFIG_BONDING is not set
+# CONFIG_EQUALIZER is not set
+CONFIG_TUN=m
+
+#
+# PHY device support
+#
+
+#
+# Wireless LAN (non-hamradio)
+#
+# CONFIG_NET_RADIO is not set
+
+#
+# Wan interfaces
+#
+# CONFIG_WAN is not set
+CONFIG_PPP=m
+# CONFIG_PPP_MULTILINK is not set
+# CONFIG_PPP_FILTER is not set
+# CONFIG_PPP_ASYNC is not set
+# CONFIG_PPP_SYNC_TTY is not set
+# CONFIG_PPP_DEFLATE is not set
+# CONFIG_PPP_BSDCOMP is not set
+# CONFIG_PPP_MPPE is not set
+# CONFIG_PPPOE is not set
+CONFIG_SLIP=m
+# CONFIG_SLIP_COMPRESSED is not set
+CONFIG_SLHC=m
+# CONFIG_SLIP_SMART is not set
+# CONFIG_SLIP_MODE_SLIP6 is not set
+# CONFIG_SHAPER is not set
+# CONFIG_NETCONSOLE is not set
+# CONFIG_NETPOLL is not set
+# CONFIG_NET_POLL_CONTROLLER is not set
+
+#
+# Connector - unified userspace <-> kernelspace linker
+#
+# CONFIG_CONNECTOR is not set
+
+#
+# File systems
+#
+CONFIG_EXT2_FS=y
+# CONFIG_EXT2_FS_XATTR is not set
+# CONFIG_EXT2_FS_XIP is not set
+CONFIG_EXT3_FS=y
+# CONFIG_EXT3_FS_XATTR is not set
+# CONFIG_EXT4DEV_FS is not set
+CONFIG_JBD=y
+# CONFIG_JBD_DEBUG is not set
+CONFIG_REISERFS_FS=y
+# CONFIG_REISERFS_CHECK is not set
+# CONFIG_REISERFS_PROC_INFO is not set
+# CONFIG_REISERFS_FS_XATTR is not set
+# CONFIG_JFS_FS is not set
+# CONFIG_FS_POSIX_ACL is not set
+# CONFIG_XFS_FS is not set
+# CONFIG_GFS2_FS is not set
+# CONFIG_OCFS2_FS is not set
+# CONFIG_MINIX_FS is not set
+# CONFIG_ROMFS_FS is not set
+CONFIG_INOTIFY=y
+CONFIG_INOTIFY_USER=y
+CONFIG_QUOTA=y
+# CONFIG_QFMT_V1 is not set
+# CONFIG_QFMT_V2 is not set
+CONFIG_QUOTACTL=y
+CONFIG_DNOTIFY=y
+CONFIG_AUTOFS_FS=m
+CONFIG_AUTOFS4_FS=m
+CONFIG_FUSE_FS=m
+
+#
+# CD-ROM/DVD Filesystems
+#
+CONFIG_ISO9660_FS=m
+CONFIG_JOLIET=y
+# CONFIG_ZISOFS is not set
+# CONFIG_UDF_FS is not set
+
+#
+# DOS/FAT/NT Filesystems
+#
+CONFIG_FAT_FS=m
+CONFIG_MSDOS_FS=m
+CONFIG_VFAT_FS=m
+CONFIG_FAT_DEFAULT_CODEPAGE=437
+CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1"
+# CONFIG_NTFS_FS is not set
+
+#
+# Pseudo filesystems
+#
+CONFIG_PROC_FS=y
+CONFIG_PROC_KCORE=y
+CONFIG_PROC_SYSCTL=y
+CONFIG_SYSFS=y
+CONFIG_TMPFS=y
+# CONFIG_TMPFS_POSIX_ACL is not set
+# CONFIG_HUGETLB_PAGE is not set
+CONFIG_RAMFS=y
+# CONFIG_CONFIGFS_FS is not set
+
+#
+# Miscellaneous filesystems
+#
+# CONFIG_ADFS_FS is not set
+# CONFIG_AFFS_FS is not set
+# CONFIG_HFS_FS is not set
+# CONFIG_HFSPLUS_FS is not set
+# CONFIG_BEFS_FS is not set
+# CONFIG_BFS_FS is not set
+# CONFIG_EFS_FS is not set
+# CONFIG_CRAMFS is not set
+# CONFIG_VXFS_FS is not set
+# CONFIG_HPFS_FS is not set
+# CONFIG_QNX4FS_FS is not set
+# CONFIG_SYSV_FS is not set
+# CONFIG_UFS_FS is not set
+
+#
+# Network File Systems
+#
+# CONFIG_NFS_FS is not set
+# CONFIG_NFSD is not set
+# CONFIG_SMB_FS is not set
+# CONFIG_CIFS is not set
+# CONFIG_NCP_FS is not set
+# CONFIG_CODA_FS is not set
+# CONFIG_AFS_FS is not set
+# CONFIG_9P_FS is not set
+
+#
+# Partition Types
+#
+# CONFIG_PARTITION_ADVANCED is not set
+CONFIG_MSDOS_PARTITION=y
+
+#
+# Native Language Support
+#
+CONFIG_NLS=y
+CONFIG_NLS_DEFAULT="iso8859-1"
+# CONFIG_NLS_CODEPAGE_437 is not set
+# CONFIG_NLS_CODEPAGE_737 is not set
+# CONFIG_NLS_CODEPAGE_775 is not set
+# CONFIG_NLS_CODEPAGE_850 is not set
+# CONFIG_NLS_CODEPAGE_852 is not set
+# CONFIG_NLS_CODEPAGE_855 is not set
+# CONFIG_NLS_CODEPAGE_857 is not set
+# CONFIG_NLS_CODEPAGE_860 is not set
+# CONFIG_NLS_CODEPAGE_861 is not set
+# CONFIG_NLS_CODEPAGE_862 is not set
+# CONFIG_NLS_CODEPAGE_863 is not set
+# CONFIG_NLS_CODEPAGE_864 is not set
+# CONFIG_NLS_CODEPAGE_865 is not set
+# CONFIG_NLS_CODEPAGE_866 is not set
+# CONFIG_NLS_CODEPAGE_869 is not set
+# CONFIG_NLS_CODEPAGE_936 is not set
+# CONFIG_NLS_CODEPAGE_950 is not set
+# CONFIG_NLS_CODEPAGE_932 is not set
+# CONFIG_NLS_CODEPAGE_949 is not set
+# CONFIG_NLS_CODEPAGE_874 is not set
+# CONFIG_NLS_ISO8859_8 is not set
+# CONFIG_NLS_CODEPAGE_1250 is not set
+# CONFIG_NLS_CODEPAGE_1251 is not set
+# CONFIG_NLS_ASCII is not set
+# CONFIG_NLS_ISO8859_1 is not set
+# CONFIG_NLS_ISO8859_2 is not set
+# CONFIG_NLS_ISO8859_3 is not set
+# CONFIG_NLS_ISO8859_4 is not set
+# CONFIG_NLS_ISO8859_5 is not set
+# CONFIG_NLS_ISO8859_6 is not set
+# CONFIG_NLS_ISO8859_7 is not set
+# CONFIG_NLS_ISO8859_9 is not set
+# CONFIG_NLS_ISO8859_13 is not set
+# CONFIG_NLS_ISO8859_14 is not set
+# CONFIG_NLS_ISO8859_15 is not set
+# CONFIG_NLS_KOI8_R is not set
+# CONFIG_NLS_KOI8_U is not set
+# CONFIG_NLS_UTF8 is not set
+
+#
+# Distributed Lock Manager
+#
+# CONFIG_DLM is not set
+
+#
+# Security options
+#
+# CONFIG_KEYS is not set
+# CONFIG_SECURITY is not set
+
+#
+# Cryptographic options
+#
+# CONFIG_CRYPTO is not set
+
+#
+# Library routines
+#
+CONFIG_BITREVERSE=m
+# CONFIG_CRC_CCITT is not set
+# CONFIG_CRC16 is not set
+CONFIG_CRC32=m
+# CONFIG_LIBCRC32C is not set
+CONFIG_PLIST=y
+
+#
+# Multi-device support (RAID and LVM)
+#
+# CONFIG_MD is not set
+# CONFIG_INPUT is not set
+
+#
+# Kernel hacking
+#
+# CONFIG_PRINTK_TIME is not set
+CONFIG_ENABLE_MUST_CHECK=y
+# CONFIG_UNUSED_SYMBOLS is not set
+# CONFIG_DEBUG_FS is not set
+CONFIG_DEBUG_KERNEL=y
+CONFIG_LOG_BUF_SHIFT=14
+CONFIG_DETECT_SOFTLOCKUP=y
+# CONFIG_SCHEDSTATS is not set
+CONFIG_DEBUG_SLAB=y
+# CONFIG_DEBUG_SLAB_LEAK is not set
+# CONFIG_DEBUG_RT_MUTEXES is not set
+# CONFIG_RT_MUTEX_TESTER is not set
+# CONFIG_DEBUG_SPINLOCK is not set
+# CONFIG_DEBUG_MUTEXES is not set
+# CONFIG_DEBUG_RWSEMS is not set
+# CONFIG_DEBUG_SPINLOCK_SLEEP is not set
+# CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
+# CONFIG_DEBUG_KOBJECT is not set
+CONFIG_DEBUG_BUGVERBOSE=y
+CONFIG_DEBUG_INFO=y
+# CONFIG_DEBUG_VM is not set
+# CONFIG_DEBUG_LIST is not set
+CONFIG_FRAME_POINTER=y
+CONFIG_FORCED_INLINING=y
+# CONFIG_RCU_TORTURE_TEST is not set
+# CONFIG_FAULT_INJECTION is not set
+# CONFIG_GPROF is not set
+# CONFIG_GCOV is not set
diff --git a/pkgs/os-specific/linux/kernel/linux-2.6.20.nix b/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
index aedaed0f351a..22a2cee5aad2 100644
--- a/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
+++ b/pkgs/os-specific/linux/kernel/linux-2.6.20.nix
@@ -5,6 +5,9 @@
   # symbolic name and `patch' is the actual patch.  The patch may
   # optionally be compressed with gzip or bzip2.
 , kernelPatches ? []
+
+, # Whether to build a User-Mode Linux kernel.
+  userModeLinux ? false
 }:
 
 assert stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux";
@@ -24,6 +27,7 @@ stdenv.mkDerivation {
   extraConfig = lib.concatStrings (map (p: "\n" + p.extraConfig + "\n") kernelPatches);
 
   config =
+    if userModeLinux then ./config-2.6.20-uml else
     if stdenv.system == "i686-linux" then ./config-2.6.20-i686-smp else
     if stdenv.system == "x86_64-linux" then ./config-2.6.20-x86_64-smp else
     abort "No kernel configuration for your platform!";
@@ -31,15 +35,21 @@ stdenv.mkDerivation {
   buildInputs = [perl mktemp];
   
   arch =
+    if userModeLinux then "um" else
     if stdenv.system == "i686-linux" then "i386" else
     if stdenv.system == "x86_64-linux" then "x86_64" else
     abort "";
 
+  makeFlagsArray = if userModeLinux then ["ARCH=um"] else [];
+
   inherit module_init_tools;
 
   meta = {
     description =
-      "The Linux kernel" +
+      (if userModeLinux then
+        "User-Mode Linux"
+       else
+        "The Linux kernel") +
       (if kernelPatches == [] then "" else
         " (with patches: "
         + lib.concatStrings (lib.intersperse ", " (map (x: x.name) kernelPatches))
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 42f169dd137c..512150f0d433 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2294,6 +2294,11 @@ rec {
     ];
   };
 
+  umlNew = import ../os-specific/linux/kernel/linux-2.6.20.nix {
+    inherit fetchurl stdenv perl mktemp module_init_tools;
+    userModeLinux = true;
+  };
+
   libselinux = import ../os-specific/linux/libselinux {
     inherit fetchurl stdenv libsepol;
   };