arch/um: make it work with defconfig and x86_64

arch/um/defconfig only lists one default configuration, and that applies
only to the i386 architecture.  Replace it with two minimal
configuration files generated using `make savedefconfig`:

  i386_defconfig and x86_64_defconfig

The build scripts now require two updates:

1. um's Kconfig (arch/x86/um/Kconfig) should specify an ARCH_DEFCONFIG
   section explicitly pointing to these scripts if the required
   variables are set.  Take care to remove the DEFCONFIG_LIST section
   defined in the included file arch/um/Kconfig.common.

2. um's Makefile (arch/um/Makefile) should set KBUILD_DEFCONFIG properly
   for the top-level Makefile to pick up.  Copy the logic in
   arch/x86/Makefile to properly pick the defconfig file depending on
   the actual architecture; except we're working with $SUBARCH here,
   instead of $ARCH.

Now, you can do:

  $ ARCH=um make defconfig
  $ ARCH=um make

and successfully build User-Mode Linux on an x86_64 box in default
configuration.

Cc: Richard Weinberger <richard@nod.at>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/Kconfig.common

@@ -1,8 +1,3 @@
-config DEFCONFIG_LIST
-	string
-	option defconfig_list
-	default "arch/$ARCH/defconfig"
-
 config UML
 	bool
 	default y

arch/um/Makefile

@@ -6,6 +6,17 @@
 # Licensed under the GPL
 #
 
+# select defconfig based on actual architecture
+ifeq ($(SUBARCH),x86)
+  ifeq ($(shell uname -m),x86_64)
+        KBUILD_DEFCONFIG := x86_64_defconfig
+  else
+        KBUILD_DEFCONFIG := i386_defconfig
+  endif
+else
+        KBUILD_DEFCONFIG := $(SUBARCH)_defconfig
+endif
+
 ARCH_DIR := arch/um
 OS := $(shell uname -s)
 # We require bash because the vmlinux link and loader script cpp use bash

arch/um/configs/i386_defconfig

@@ -0,0 +1,76 @@
+CONFIG_3_LEVEL_PGTABLES=y
+# CONFIG_COMPACTION is not set
+CONFIG_BINFMT_MISC=m
+CONFIG_HOSTFS=y
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_KERNEL_STACK_ORDER=1
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_BSD_PROCESS_ACCT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=14
+CONFIG_CGROUPS=y
+CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CPUSETS=y
+CONFIG_CGROUP_CPUACCT=y
+CONFIG_RESOURCE_COUNTERS=y
+CONFIG_CGROUP_SCHED=y
+CONFIG_BLK_CGROUP=y
+# CONFIG_PID_NS is not set
+CONFIG_SYSFS_DEPRECATED=y
+CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+CONFIG_SLAB=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+# CONFIG_BLK_DEV_BSG is not set
+CONFIG_IOSCHED_CFQ=m
+CONFIG_SSL=y
+CONFIG_NULL_CHAN=y
+CONFIG_PORT_CHAN=y
+CONFIG_PTY_CHAN=y
+CONFIG_TTY_CHAN=y
+CONFIG_XTERM_CHAN=y
+CONFIG_CON_CHAN="pts"
+CONFIG_SSL_CHAN="pts"
+CONFIG_UML_SOUND=m
+CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_BLK_DEV_UBD=y
+CONFIG_BLK_DEV_LOOP=m
+CONFIG_BLK_DEV_NBD=m
+CONFIG_DUMMY=m
+CONFIG_TUN=m
+CONFIG_PPP=m
+CONFIG_SLIP=m
+CONFIG_LEGACY_PTY_COUNT=32
+# CONFIG_HW_RANDOM is not set
+CONFIG_UML_RANDOM=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+# CONFIG_INET_LRO is not set
+# CONFIG_IPV6 is not set
+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_SLIRP=y
+CONFIG_EXT4_FS=y
+CONFIG_REISERFS_FS=y
+CONFIG_QUOTA=y
+CONFIG_AUTOFS4_FS=m
+CONFIG_ISO9660_FS=m
+CONFIG_JOLIET=y
+CONFIG_PROC_KCORE=y
+CONFIG_TMPFS=y
+CONFIG_NLS=y
+CONFIG_DEBUG_INFO=y
+CONFIG_DEBUG_KERNEL=y

arch/um/configs/x86_64_defconfig

@@ -0,0 +1,75 @@
+# CONFIG_COMPACTION is not set
+CONFIG_BINFMT_MISC=m
+CONFIG_HOSTFS=y
+CONFIG_MAGIC_SYSRQ=y
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_BSD_PROCESS_ACCT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=14
+CONFIG_CGROUPS=y
+CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_DEVICE=y
+CONFIG_CPUSETS=y
+CONFIG_CGROUP_CPUACCT=y
+CONFIG_RESOURCE_COUNTERS=y
+CONFIG_CGROUP_SCHED=y
+CONFIG_BLK_CGROUP=y
+# CONFIG_PID_NS is not set
+CONFIG_SYSFS_DEPRECATED=y
+CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+CONFIG_SLAB=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+# CONFIG_BLK_DEV_BSG is not set
+CONFIG_IOSCHED_CFQ=m
+CONFIG_SSL=y
+CONFIG_NULL_CHAN=y
+CONFIG_PORT_CHAN=y
+CONFIG_PTY_CHAN=y
+CONFIG_TTY_CHAN=y
+CONFIG_XTERM_CHAN=y
+CONFIG_CON_CHAN="pts"
+CONFIG_SSL_CHAN="pts"
+CONFIG_UML_SOUND=m
+CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_BLK_DEV_UBD=y
+CONFIG_BLK_DEV_LOOP=m
+CONFIG_BLK_DEV_NBD=m
+CONFIG_DUMMY=m
+CONFIG_TUN=m
+CONFIG_PPP=m
+CONFIG_SLIP=m
+CONFIG_LEGACY_PTY_COUNT=32
+# CONFIG_HW_RANDOM is not set
+CONFIG_UML_RANDOM=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+# CONFIG_INET_LRO is not set
+# CONFIG_IPV6 is not set
+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_SLIRP=y
+CONFIG_EXT4_FS=y
+CONFIG_REISERFS_FS=y
+CONFIG_QUOTA=y
+CONFIG_AUTOFS4_FS=m
+CONFIG_ISO9660_FS=m
+CONFIG_JOLIET=y
+CONFIG_PROC_KCORE=y
+CONFIG_TMPFS=y
+CONFIG_NLS=y
+CONFIG_DEBUG_INFO=y
+CONFIG_FRAME_WARN=1024
+CONFIG_DEBUG_KERNEL=y

arch/x86/um/Kconfig

@@ -31,6 +31,11 @@ config X86_64
 	def_bool 64BIT
 	select MODULES_USE_ELF_RELA
 
+config ARCH_DEFCONFIG
+	string
+	default "arch/um/configs/i386_defconfig" if X86_32
+	default "arch/um/configs/x86_64_defconfig" if X86_64
+
 config RWSEM_XCHGADD_ALGORITHM
 	def_bool 64BIT