openwrtv4/config/Config-kernel.in

# Copyright (C) 2006-2014 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#

config KERNEL_BUILD_USER
	string "Custom Kernel Build User Name"
	default ""
	help
	  Sets the Kernel build user string, which for example will be returned
	  by 'uname -a' on running systems.
	  If not set, uses system user at build time.

config KERNEL_BUILD_DOMAIN
	string "Custom Kernel Build Domain Name"
	default ""
	help
	  Sets the Kernel build domain string, which for example will be
	  returned by 'uname -a' on running systems.
	  If not set, uses system hostname at build time.

config KERNEL_PRINTK
	bool "Enable support for printk"
	default y

config KERNEL_CRASHLOG
	bool "Crash logging"
	depends on !(arm || powerpc || sparc || TARGET_uml || i386 || x86_64)
	default y

config KERNEL_SWAP
	bool "Support for paging of anonymous memory (swap)"
	default y if !SMALL_FLASH

config KERNEL_DEBUG_FS
	bool "Compile the kernel with debug filesystem enabled"
	default y
	help
	  debugfs is a virtual file system that kernel developers use to put
	  debugging files into. Enable this option to be able to read and
	  write to these files. Many common debugging facilities, such as
	  ftrace, require the existence of debugfs.

config KERNEL_MIPS_FPU_EMULATOR
	bool "Compile the kernel with MIPS FPU Emulator"
	default y if TARGET_pistachio
	depends on (mips || mipsel || mips64 || mips64el)

config KERNEL_ARM_PMU
	bool
	default n
	depends on (arm || aarch64)

config KERNEL_PERF_EVENTS
	bool "Compile the kernel with performance events and counters"
	default n
	select KERNEL_ARM_PMU if (arm || aarch64)

config KERNEL_PROFILING
	bool "Compile the kernel with profiling enabled"
	default n
	select KERNEL_PERF_EVENTS
	help
	  Enable the extended profiling support mechanisms used by profilers such
	  as OProfile.

config KERNEL_TASKSTATS
	bool "Compile the kernel with task resource/io statistics and accounting"
	default n
	help
	  Enable the collection and publishing of task/io statistics and
	  accounting.  Enable this option to enable i/o monitoring in system
	  monitors.

if KERNEL_TASKSTATS

	config KERNEL_TASK_DELAY_ACCT
		def_bool y

	config KERNEL_TASK_IO_ACCOUNTING
		def_bool y

	config KERNEL_TASK_XACCT
		def_bool y

endif

config KERNEL_KALLSYMS
	bool "Compile the kernel with symbol table information"
	default y if !SMALL_FLASH
	help
	  This will give you more information in stack traces from kernel oopses.

config KERNEL_FTRACE
	bool "Compile the kernel with tracing support"
	depends on !TARGET_uml
	default n

config KERNEL_FTRACE_SYSCALLS
	bool "Trace system calls"
	depends on KERNEL_FTRACE
	default n

config KERNEL_ENABLE_DEFAULT_TRACERS
	bool "Trace process context switches and events"
	depends on KERNEL_FTRACE
	default n

config KERNEL_FUNCTION_TRACER
	bool "Function tracer"
	depends on KERNEL_FTRACE
	default n

config KERNEL_FUNCTION_GRAPH_TRACER
	bool "Function graph tracer"
	depends on KERNEL_FUNCTION_TRACER
	default n

config KERNEL_DYNAMIC_FTRACE
	bool "Enable/disable function tracing dynamically"
	depends on KERNEL_FUNCTION_TRACER
	default n

config KERNEL_FUNCTION_PROFILER
	bool "Function profiler"
	depends on KERNEL_FUNCTION_TRACER
	default n

config KERNEL_DEBUG_KERNEL
	bool
	default n

config KERNEL_DEBUG_INFO
	bool "Compile the kernel with debug information"
	default y if !SMALL_FLASH
	select KERNEL_DEBUG_KERNEL
	help
	  This will compile your kernel and modules with debug information.

config KERNEL_DEBUG_LL_UART_NONE
	bool
	default n
	depends on arm

config KERNEL_DEBUG_LL
	bool
	default n
	depends on arm
	select KERNEL_DEBUG_LL_UART_NONE
	help
	  ARM low level debugging.

config KERNEL_DYNAMIC_DEBUG
	bool "Compile the kernel with dynamic printk"
	select KERNEL_DEBUG_FS
	default n
	help
	  Compiles debug level messages into the kernel, which would not
	  otherwise be available at runtime. These messages can then be
	  enabled/disabled based on various levels of scope - per source file,
	  function, module, format string, and line number. This mechanism
	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
	  enlarges the kernel text size by about 2%.

config KERNEL_EARLY_PRINTK
	bool "Compile the kernel with early printk"
	default y if TARGET_bcm53xx
	default n
	depends on arm
	select KERNEL_DEBUG_KERNEL
	select KERNEL_DEBUG_LL if arm
	help
	  Compile the kernel with early printk support.  This is only useful for
	  debugging purposes to send messages over the serial console in early boot.
	  Enable this to debug early boot problems.

config KERNEL_KPROBES
	bool "Compile the kernel with kprobes support"
	default n
	select KERNEL_FTRACE
	select KERNEL_PERF_EVENTS
	help
	  Compiles the kernel with KPROBES support, which allows you to trap
	  at almost any kernel address and execute a callback function.
	  register_kprobe() establishes a probepoint and specifies the
	  callback. Kprobes is useful for kernel debugging, non-intrusive
	  instrumentation and testing.
	  If in doubt, say "N".

config KERNEL_KPROBE_EVENT
	bool
	default y if KERNEL_KPROBES

config KERNEL_AIO
	bool "Compile the kernel with asynchronous IO support"
	default n

config KERNEL_FHANDLE
	bool "Compile the kernel with support for fhandle syscalls"
	default n

config KERNEL_FANOTIFY
	bool "Compile the kernel with modern file notification support"
	default n

config KERNEL_BLK_DEV_BSG
	bool "Compile the kernel with SCSI generic v4 support for any block device"
	default n

config KERNEL_MAGIC_SYSRQ
	bool "Compile the kernel with SysRq support"
	default y

config KERNEL_DEBUG_PINCTRL
	bool "Compile the kernel with pinctrl debugging"
	select KERNEL_DEBUG_KERNEL

config KERNEL_DEBUG_GPIO
	bool "Compile the kernel with gpio debugging"
	select KERNEL_DEBUG_KERNEL

config KERNEL_COREDUMP
	bool

config KERNEL_ELF_CORE
	bool "Enable process core dump support"
	select KERNEL_COREDUMP
	default y if !SMALL_FLASH

config KERNEL_PROVE_LOCKING
	bool "Enable kernel lock checking"
	select KERNEL_DEBUG_KERNEL
	default n

config KERNEL_PRINTK_TIME
	bool "Enable printk timestamps"
	default y

config KERNEL_SLUB_DEBUG
	bool

config KERNEL_SLUB_DEBUG_ON
	bool

config KERNEL_SLABINFO
	select KERNEL_SLUB_DEBUG
	select KERNEL_SLUB_DEBUG_ON
	bool "Enable /proc slab debug info"

config KERNEL_PROC_PAGE_MONITOR
	bool "Enable /proc page monitoring"

config KERNEL_RELAY
	bool

config KERNEL_KEXEC
	bool "Enable kexec support"

config KERNEL_PROC_VMCORE
	bool

config KERNEL_CRASH_DUMP
	depends on i386 || x86_64 || arm || armeb
	select KERNEL_KEXEC
	select KERNEL_PROC_VMCORE
	bool "Enable support for kexec crashdump"
	default y

config USE_RFKILL
	bool "Enable rfkill support"
	default RFKILL_SUPPORT

config USE_SPARSE
	bool "Enable sparse check during kernel build"
	default n

config KERNEL_DEVTMPFS
	bool "Compile the kernel with device tmpfs enabled"
	default n
	help
	  devtmpfs is a simple, kernel-managed /dev filesystem. The kernel creates
	  devices nodes for all registered devices to simplify boot, but leaves more
	  complex tasks to userspace (e.g. udev).

if KERNEL_DEVTMPFS

	config KERNEL_DEVTMPFS_MOUNT
		bool "Automatically mount devtmpfs after root filesystem is mounted"
		default n

endif

config KERNEL_KEYS
    bool "Enable kernel access key retention support"
    default n

config KERNEL_PERSISTENT_KEYRINGS
    bool "Enable kernel persistent keyrings"
    depends on KERNEL_KEYS
    default n

config KERNEL_BIG_KEYS
    bool "Enable large payload keys on kernel keyrings"
    depends on KERNEL_KEYS
    default n

config KERNEL_ENCRYPTED_KEYS
    tristate "Enable keys with encrypted payloads on kernel keyrings"
    depends on KERNEL_KEYS
    default n

#
# CGROUP support symbols
#

config KERNEL_CGROUPS
	bool "Enable kernel cgroups"
	default n

if KERNEL_CGROUPS

	config KERNEL_CGROUP_DEBUG
		bool "Example debug cgroup subsystem"
		default n
		help
		  This option enables a simple cgroup subsystem that
		  exports useful debugging information about the cgroups
		  framework.

	config KERNEL_FREEZER
		bool
		default y if KERNEL_CGROUP_FREEZER

	config KERNEL_CGROUP_FREEZER
		bool "Freezer cgroup subsystem"
		default y
		help
		  Provides a way to freeze and unfreeze all tasks in a
		  cgroup.

	config KERNEL_CGROUP_DEVICE
		bool "Device controller for cgroups"
		default y
		help
		  Provides a cgroup implementing whitelists for devices which
		  a process in the cgroup can mknod or open.

	config KERNEL_CGROUP_PIDS
		bool "PIDs cgroup subsystem"
		default y
		help
		  Provides enforcement of process number limits in the scope of a
		  cgroup.

	config KERNEL_CPUSETS
		bool "Cpuset support"
		default n
		help
		  This option will let you create and manage CPUSETs which
		  allow dynamically partitioning a system into sets of CPUs and
		  Memory Nodes and assigning tasks to run only within those sets.
		  This is primarily useful on large SMP or NUMA systems.

	config KERNEL_PROC_PID_CPUSET
		bool "Include legacy /proc/<pid>/cpuset file"
		default n
		depends on KERNEL_CPUSETS

	config KERNEL_CGROUP_CPUACCT
		bool "Simple CPU accounting cgroup subsystem"
		default n
		help
		  Provides a simple Resource Controller for monitoring the
		  total CPU consumed by the tasks in a cgroup.

	config KERNEL_RESOURCE_COUNTERS
		bool "Resource counters"
		default n
		help
		  This option enables controller independent resource accounting
		  infrastructure that works with cgroups.

	config KERNEL_MM_OWNER
		bool
		default y if KERNEL_MEMCG

	config KERNEL_MEMCG
		bool "Memory Resource Controller for Control Groups"
		default n
		depends on KERNEL_RESOURCE_COUNTERS || !LINUX_3_18
		help
		  Provides a memory resource controller that manages both anonymous
		  memory and page cache. (See Documentation/cgroups/memory.txt)

		  Note that setting this option increases fixed memory overhead
		  associated with each page of memory in the system. By this,
		  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
		  usage tracking struct at boot. Total amount of this is printed out
		  at boot.

		  Only enable when you're ok with these tradeoffs and really
		  sure you need the memory resource controller. Even when you enable
		  this, you can set "cgroup_disable=memory" at your boot option to
		  disable memory resource controller and you can avoid overheads
		  (but lose benefits of memory resource controller).

		  This config option also selects MM_OWNER config option, which
		  could in turn add some fork/exit overhead.

	config KERNEL_MEMCG_SWAP
		bool "Memory Resource Controller Swap Extension"
		default n
		depends on KERNEL_MEMCG
		help
		  Add swap management feature to memory resource controller. When you
		  enable this, you can limit mem+swap usage per cgroup. In other words,
		  when you disable this, memory resource controller has no cares to
		  usage of swap...a process can exhaust all of the swap. This extension
		  is useful when you want to avoid exhaustion swap but this itself
		  adds more overheads and consumes memory for remembering information.
		  Especially if you use 32bit system or small memory system, please
		  be careful about enabling this. When memory resource controller
		  is disabled by boot option, this will be automatically disabled and
		  there will be no overhead from this. Even when you set this config=y,
		  if boot option "swapaccount=0" is set, swap will not be accounted.
		  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
		  size is 4096bytes, 512k per 1Gbytes of swap.

	config KERNEL_MEMCG_SWAP_ENABLED
		bool "Memory Resource Controller Swap Extension enabled by default"
		default n
		depends on KERNEL_MEMCG_SWAP
		help
		  Memory Resource Controller Swap Extension comes with its price in
		  a bigger memory consumption. General purpose distribution kernels
		  which want to enable the feature but keep it disabled by default
		  and let the user enable it by swapaccount boot command line
		  parameter should have this option unselected.

		  Those who want to have the feature enabled by default should
		  select this option (if, for some reason, they need to disable it,
		  then swapaccount=0 does the trick).


	config KERNEL_MEMCG_KMEM
		bool "Memory Resource Controller Kernel Memory accounting (EXPERIMENTAL)"
		default n
		depends on KERNEL_MEMCG
		help
		  The Kernel Memory extension for Memory Resource Controller can limit
		  the amount of memory used by kernel objects in the system. Those are
		  fundamentally different from the entities handled by the standard
		  Memory Controller, which are page-based, and can be swapped. Users of
		  the kmem extension can use it to guarantee that no group of processes
		  will ever exhaust kernel resources alone.

	config KERNEL_CGROUP_PERF
		bool "Enable perf_event per-cpu per-container group (cgroup) monitoring"
		select KERNEL_PERF_EVENTS
		default n
		help
		  This option extends the per-cpu mode to restrict monitoring to
		  threads which belong to the cgroup specified and run on the
		  designated cpu.

	menuconfig KERNEL_CGROUP_SCHED
		bool "Group CPU scheduler"
		default n
		help
		  This feature lets CPU scheduler recognize task groups and control CPU
		  bandwidth allocation to such task groups. It uses cgroups to group
		  tasks.

	if KERNEL_CGROUP_SCHED

		config KERNEL_FAIR_GROUP_SCHED
			bool "Group scheduling for SCHED_OTHER"
			default n

		config KERNEL_CFS_BANDWIDTH
			bool "CPU bandwidth provisioning for FAIR_GROUP_SCHED"
			default n
			depends on KERNEL_FAIR_GROUP_SCHED
			help
			  This option allows users to define CPU bandwidth rates (limits) for
			  tasks running within the fair group scheduler.  Groups with no limit
			  set are considered to be unconstrained and will run with no
			  restriction.
			  See tip/Documentation/scheduler/sched-bwc.txt for more information.

		config KERNEL_RT_GROUP_SCHED
			bool "Group scheduling for SCHED_RR/FIFO"
			default n
			help
			  This feature lets you explicitly allocate real CPU bandwidth
			  to task groups. If enabled, it will also make it impossible to
			  schedule realtime tasks for non-root users until you allocate
			  realtime bandwidth for them.

	endif

	config KERNEL_BLK_CGROUP
		bool "Block IO controller"
		default y
		help
		  Generic block IO controller cgroup interface. This is the common
		  cgroup interface which should be used by various IO controlling
		  policies.

		  Currently, CFQ IO scheduler uses it to recognize task groups and
		  control disk bandwidth allocation (proportional time slice allocation)
		  to such task groups. It is also used by bio throttling logic in
		  block layer to implement upper limit in IO rates on a device.

		  This option only enables generic Block IO controller infrastructure.
		  One needs to also enable actual IO controlling logic/policy. For
		  enabling proportional weight division of disk bandwidth in CFQ, set
		  CONFIG_CFQ_GROUP_IOSCHED=y; for enabling throttling policy, set
		  CONFIG_BLK_DEV_THROTTLING=y.

	config KERNEL_DEBUG_BLK_CGROUP
		bool "Enable Block IO controller debugging"
		default n
		depends on KERNEL_BLK_CGROUP
		help
		  Enable some debugging help. Currently it exports additional stat
		  files in a cgroup which can be useful for debugging.

	config KERNEL_NET_CLS_CGROUP
		bool "Control Group Classifier"
		default y

	config KERNEL_NETPRIO_CGROUP
		bool "Network priority cgroup"
		default y

endif

#
# Namespace support symbols
#

config KERNEL_NAMESPACES
	bool "Enable kernel namespaces"
	default n

if KERNEL_NAMESPACES

	config KERNEL_UTS_NS
		bool "UTS namespace"
		default y
		help
		  In this namespace, tasks see different info provided
		  with the uname() system call.

	config KERNEL_IPC_NS
		bool "IPC namespace"
		default y
		help
		  In this namespace, tasks work with IPC ids which correspond to
		  different IPC objects in different namespaces.

	config KERNEL_USER_NS
		bool "User namespace (EXPERIMENTAL)"
		default y
		help
		  This allows containers, i.e. vservers, to use user namespaces
		  to provide different user info for different servers.

	config KERNEL_PID_NS
		bool "PID Namespaces"
		default y
		help
		  Support process id namespaces. This allows having multiple
		  processes with the same pid as long as they are in different
		  pid namespaces. This is a building block of containers.

	config KERNEL_NET_NS
		bool "Network namespace"
		default y
		help
		  Allow user space to create what appear to be multiple instances
		  of the network stack.

endif

#
# LXC related symbols
#

config KERNEL_LXC_MISC
	bool "Enable miscellaneous LXC related options"
	default n

if KERNEL_LXC_MISC

	config KERNEL_DEVPTS_MULTIPLE_INSTANCES
		bool "Support multiple instances of devpts"
		default y
		help
		  Enable support for multiple instances of devpts filesystem.
		  If you want to have isolated PTY namespaces (eg: in containers),
		  say Y here. Otherwise, say N. If enabled, each mount of devpts
		  filesystem with the '-o newinstance' option will create an
		  independent PTY namespace.

	config KERNEL_POSIX_MQUEUE
		bool "POSIX Message Queues"
		default y
		help
		  POSIX variant of message queues is a part of IPC. In POSIX message
		  queues every message has a priority which decides about succession
		  of receiving it by a process. If you want to compile and run
		  programs written e.g. for Solaris with use of its POSIX message
		  queues (functions mq_*) say Y here.

		  POSIX message queues are visible as a filesystem called 'mqueue'
		  and can be mounted somewhere if you want to do filesystem
		  operations on message queues.

endif

config KERNEL_SECCOMP_FILTER
	bool
	default n

config KERNEL_SECCOMP
	bool "Enable seccomp support"
		depends on !(TARGET_uml)
		select KERNEL_SECCOMP_FILTER
		default n
		help
		  Build kernel with support for seccomp.

#
# IPv4 configuration
#

config KERNEL_IP_MROUTE
	bool "Enable IPv4 multicast routing"
	default y
	help
	  Multicast routing requires a multicast routing daemon in
	  addition to kernel support.

#
# IPv6 configuration
#

config KERNEL_IPV6
	def_bool IPV6

if KERNEL_IPV6

	config KERNEL_IPV6_MULTIPLE_TABLES
		def_bool y

	config KERNEL_IPV6_SUBTREES
		def_bool y

	config KERNEL_IPV6_MROUTE
		bool "Enable IPv6 multicast routing"
		default y
		help
		  Multicast routing requires a multicast routing daemon in
		  addition to kernel support.

	config KERNEL_IPV6_PIMSM_V2
		def_bool n

endif

#
# NFS related symbols
#
config KERNEL_IP_PNP
	bool "Compile the kernel with rootfs on NFS"
	help
	   If you want to make your kernel boot off a NFS server as root
	   filesystem, select Y here.

if KERNEL_IP_PNP

	config KERNEL_IP_PNP_DHCP
		def_bool y

	config KERNEL_IP_PNP_BOOTP
		def_bool n

	config KERNEL_IP_PNP_RARP
		def_bool n

	config KERNEL_NFS_FS
		def_bool y

	config KERNEL_NFS_V2
		def_bool y

	config KERNEL_NFS_V3
		def_bool y

	config KERNEL_ROOT_NFS
		def_bool y

endif

menu "Filesystem ACL and attr support options"
	config USE_FS_ACL_ATTR
		bool "Use filesystem ACL and attr support by default"
		default n
		help
		  Make using ACLs (e.g. POSIX ACL, NFSv4 ACL) the default
		  for kernel and packages, except tmpfs, flash filesystems,
		  and old NFS.  Also enable userspace extended attribute support
		  by default.  (OpenWrt already has an expection it will be
		  present in the kernel).

	config KERNEL_FS_POSIX_ACL
		bool "Enable POSIX ACL support"
		default y if USE_FS_ACL_ATTR

	config KERNEL_BTRFS_FS_POSIX_ACL
		bool "Enable POSIX ACL for BtrFS Filesystems"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_EXT4_FS_POSIX_ACL
		bool "Enable POSIX ACL for Ext4 Filesystems"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_F2FS_FS_POSIX_ACL
		bool "Enable POSIX ACL for F2FS Filesystems"
		select KERNEL_FS_POSIX_ACL
		default n

	config KERNEL_JFFS2_FS_POSIX_ACL
		bool "Enable POSIX ACL for JFFS2 Filesystems"
		select KERNEL_FS_POSIX_ACL
		default n

	config KERNEL_TMPFS_POSIX_ACL
		bool "Enable POSIX ACL for TMPFS Filesystems"
		select KERNEL_FS_POSIX_ACL
		default n

	config KERNEL_CIFS_ACL
		bool "Enable CIFS ACLs"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_HFS_FS_POSIX_ACL
		bool "Enable POSIX ACL for HFS Filesystems"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_HFSPLUG_FS_POSIX_ACL
		bool "Enable POSIX ACL for HFS+ Filesystems"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_NFS_ACL_SUPPORT
		bool "Enable ACLs for NFS"
		default y if USE_FS_ACL_ATTR

	config KERNEL_NFS_V3_ACL_SUPPORT
		bool "Enable ACLs for NFSv3"
		default n

	config KERNEL_NFSD_V2_ACL_SUPPORT
		bool "Enable ACLs for NFSDv2"
		default n

	config KERNEL_NFSD_V3_ACL_SUPPORT
		bool "Enable ACLs for NFSDv3"
		default n

	config KERNEL_REISER_FS_POSIX_ACL
		bool "Enable POSIX ACLs for ReiserFS"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_XFS_POSIX_ACL
		bool "Enable POSIX ACLs for XFS"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

	config KERNEL_JFS_POSIX_ACL
		bool "Enable POSIX ACLs for JFS"
		select KERNEL_FS_POSIX_ACL
		default y if USE_FS_ACL_ATTR

endmenu

config KERNEL_DEVMEM
	bool "/dev/mem virtual device support"
	help
	  Say Y here if you want to support the /dev/mem device.
	  The /dev/mem device is used to access areas of physical
	  memory.

config KERNEL_DEVKMEM
	bool "/dev/kmem virtual device support"
	help
	  Say Y here if you want to support the /dev/kmem device. The
	  /dev/kmem device is rarely used, but can be used for certain
	  kind of kernel debugging operations.

config KERNEL_SQUASHFS_FRAGMENT_CACHE_SIZE
	int "Number of squashfs fragments cached"
	default 2 if (SMALL_FLASH && !LOW_MEMORY_FOOTPRINT)
	default 3

#
# compile optimiziation setting
#
choice
	prompt "Compiler optimization level"
	default KERNEL_CC_OPTIMIZE_FOR_SIZE if SMALL_FLASH

config KERNEL_CC_OPTIMIZE_FOR_PERFORMANCE
	bool "Optimize for performance"
	help
	  This is the default optimization level for the kernel, building
	  with the "-O2" compiler flag for best performance and most
	  helpful compile-time warnings.

config KERNEL_CC_OPTIMIZE_FOR_SIZE
	bool "Optimize for size"
	help
	  Enabling this option will pass "-Os" instead of "-O2" to
	  your compiler resulting in a smaller kernel.

endchoice