| config SELECT_MEMORY_MODEL | 
 | 	def_bool y | 
 | 	depends on ARCH_SELECT_MEMORY_MODEL | 
 |  | 
 | choice | 
 | 	prompt "Memory model" | 
 | 	depends on SELECT_MEMORY_MODEL | 
 | 	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT | 
 | 	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT | 
 | 	default FLATMEM_MANUAL | 
 |  | 
 | config FLATMEM_MANUAL | 
 | 	bool "Flat Memory" | 
 | 	depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE | 
 | 	help | 
 | 	  This option allows you to change some of the ways that | 
 | 	  Linux manages its memory internally.  Most users will | 
 | 	  only have one option here: FLATMEM.  This is normal | 
 | 	  and a correct option. | 
 |  | 
 | 	  Some users of more advanced features like NUMA and | 
 | 	  memory hotplug may have different options here. | 
 | 	  DISCONTIGMEM is a more mature, better tested system, | 
 | 	  but is incompatible with memory hotplug and may suffer | 
 | 	  decreased performance over SPARSEMEM.  If unsure between | 
 | 	  "Sparse Memory" and "Discontiguous Memory", choose | 
 | 	  "Discontiguous Memory". | 
 |  | 
 | 	  If unsure, choose this option (Flat Memory) over any other. | 
 |  | 
 | config DISCONTIGMEM_MANUAL | 
 | 	bool "Discontiguous Memory" | 
 | 	depends on ARCH_DISCONTIGMEM_ENABLE | 
 | 	help | 
 | 	  This option provides enhanced support for discontiguous | 
 | 	  memory systems, over FLATMEM.  These systems have holes | 
 | 	  in their physical address spaces, and this option provides | 
 | 	  more efficient handling of these holes.  However, the vast | 
 | 	  majority of hardware has quite flat address spaces, and | 
 | 	  can have degraded performance from the extra overhead that | 
 | 	  this option imposes. | 
 |  | 
 | 	  Many NUMA configurations will have this as the only option. | 
 |  | 
 | 	  If unsure, choose "Flat Memory" over this option. | 
 |  | 
 | config SPARSEMEM_MANUAL | 
 | 	bool "Sparse Memory" | 
 | 	depends on ARCH_SPARSEMEM_ENABLE | 
 | 	help | 
 | 	  This will be the only option for some systems, including | 
 | 	  memory hotplug systems.  This is normal. | 
 |  | 
 | 	  For many other systems, this will be an alternative to | 
 | 	  "Discontiguous Memory".  This option provides some potential | 
 | 	  performance benefits, along with decreased code complexity, | 
 | 	  but it is newer, and more experimental. | 
 |  | 
 | 	  If unsure, choose "Discontiguous Memory" or "Flat Memory" | 
 | 	  over this option. | 
 |  | 
 | endchoice | 
 |  | 
 | config DISCONTIGMEM | 
 | 	def_bool y | 
 | 	depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL | 
 |  | 
 | config SPARSEMEM | 
 | 	def_bool y | 
 | 	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL | 
 |  | 
 | config FLATMEM | 
 | 	def_bool y | 
 | 	depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL | 
 |  | 
 | config FLAT_NODE_MEM_MAP | 
 | 	def_bool y | 
 | 	depends on !SPARSEMEM | 
 |  | 
 | # | 
 | # Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's | 
 | # to represent different areas of memory.  This variable allows | 
 | # those dependencies to exist individually. | 
 | # | 
 | config NEED_MULTIPLE_NODES | 
 | 	def_bool y | 
 | 	depends on DISCONTIGMEM || NUMA | 
 |  | 
 | config HAVE_MEMORY_PRESENT | 
 | 	def_bool y | 
 | 	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM | 
 |  | 
 | # | 
 | # SPARSEMEM_EXTREME (which is the default) does some bootmem | 
 | # allocations when memory_present() is called.  If this cannot | 
 | # be done on your architecture, select this option.  However, | 
 | # statically allocating the mem_section[] array can potentially | 
 | # consume vast quantities of .bss, so be careful. | 
 | # | 
 | # This option will also potentially produce smaller runtime code | 
 | # with gcc 3.4 and later. | 
 | # | 
 | config SPARSEMEM_STATIC | 
 | 	bool | 
 |  | 
 | # | 
 | # Architecture platforms which require a two level mem_section in SPARSEMEM | 
 | # must select this option. This is usually for architecture platforms with | 
 | # an extremely sparse physical address space. | 
 | # | 
 | config SPARSEMEM_EXTREME | 
 | 	def_bool y | 
 | 	depends on SPARSEMEM && !SPARSEMEM_STATIC | 
 |  | 
 | config SPARSEMEM_VMEMMAP_ENABLE | 
 | 	bool | 
 |  | 
 | config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER | 
 | 	def_bool y | 
 | 	depends on SPARSEMEM && X86_64 | 
 |  | 
 | config SPARSEMEM_VMEMMAP | 
 | 	bool "Sparse Memory virtual memmap" | 
 | 	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE | 
 | 	default y | 
 | 	help | 
 | 	 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise | 
 | 	 pfn_to_page and page_to_pfn operations.  This is the most | 
 | 	 efficient option when sufficient kernel resources are available. | 
 |  | 
 | config HAVE_MEMBLOCK | 
 | 	bool | 
 |  | 
 | config HAVE_MEMBLOCK_NODE_MAP | 
 | 	bool | 
 |  | 
 | config HAVE_MEMBLOCK_PHYS_MAP | 
 | 	bool | 
 |  | 
 | config HAVE_GENERIC_RCU_GUP | 
 | 	bool | 
 |  | 
 | config ARCH_DISCARD_MEMBLOCK | 
 | 	bool | 
 |  | 
 | config NO_BOOTMEM | 
 | 	bool | 
 |  | 
 | config MEMORY_ISOLATION | 
 | 	bool | 
 |  | 
 | config MOVABLE_NODE | 
 | 	bool "Enable to assign a node which has only movable memory" | 
 | 	depends on HAVE_MEMBLOCK | 
 | 	depends on NO_BOOTMEM | 
 | 	depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG | 
 | 	depends on NUMA | 
 | 	default n | 
 | 	help | 
 | 	  Allow a node to have only movable memory.  Pages used by the kernel, | 
 | 	  such as direct mapping pages cannot be migrated.  So the corresponding | 
 | 	  memory device cannot be hotplugged.  This option allows the following | 
 | 	  two things: | 
 | 	  - When the system is booting, node full of hotpluggable memory can | 
 | 	  be arranged to have only movable memory so that the whole node can | 
 | 	  be hot-removed. (need movable_node boot option specified). | 
 | 	  - After the system is up, the option allows users to online all the | 
 | 	  memory of a node as movable memory so that the whole node can be | 
 | 	  hot-removed. | 
 |  | 
 | 	  Users who don't use the memory hotplug feature are fine with this | 
 | 	  option on since they don't specify movable_node boot option or they | 
 | 	  don't online memory as movable. | 
 |  | 
 | 	  Say Y here if you want to hotplug a whole node. | 
 | 	  Say N here if you want kernel to use memory on all nodes evenly. | 
 |  | 
 | # | 
 | # Only be set on architectures that have completely implemented memory hotplug | 
 | # feature. If you are not sure, don't touch it. | 
 | # | 
 | config HAVE_BOOTMEM_INFO_NODE | 
 | 	def_bool n | 
 |  | 
 | # eventually, we can have this option just 'select SPARSEMEM' | 
 | config MEMORY_HOTPLUG | 
 | 	bool "Allow for memory hot-add" | 
 | 	depends on SPARSEMEM || X86_64_ACPI_NUMA | 
 | 	depends on ARCH_ENABLE_MEMORY_HOTPLUG | 
 | 	depends on COMPILE_TEST || !KASAN | 
 |  | 
 | config MEMORY_HOTPLUG_SPARSE | 
 | 	def_bool y | 
 | 	depends on SPARSEMEM && MEMORY_HOTPLUG | 
 |  | 
 | config MEMORY_HOTPLUG_DEFAULT_ONLINE | 
 |         bool "Online the newly added memory blocks by default" | 
 |         default n | 
 |         depends on MEMORY_HOTPLUG | 
 |         help | 
 | 	  This option sets the default policy setting for memory hotplug | 
 | 	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which | 
 | 	  determines what happens to newly added memory regions. Policy setting | 
 | 	  can always be changed at runtime. | 
 | 	  See Documentation/memory-hotplug.txt for more information. | 
 |  | 
 | 	  Say Y here if you want all hot-plugged memory blocks to appear in | 
 | 	  'online' state by default. | 
 | 	  Say N here if you want the default policy to keep all hot-plugged | 
 | 	  memory blocks in 'offline' state. | 
 |  | 
 | config MEMORY_HOTREMOVE | 
 | 	bool "Allow for memory hot remove" | 
 | 	select MEMORY_ISOLATION | 
 | 	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) | 
 | 	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE | 
 | 	depends on MIGRATION | 
 |  | 
 | # Heavily threaded applications may benefit from splitting the mm-wide | 
 | # page_table_lock, so that faults on different parts of the user address | 
 | # space can be handled with less contention: split it at this NR_CPUS. | 
 | # Default to 4 for wider testing, though 8 might be more appropriate. | 
 | # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. | 
 | # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. | 
 | # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. | 
 | # | 
 | config SPLIT_PTLOCK_CPUS | 
 | 	int | 
 | 	default "999999" if !MMU | 
 | 	default "999999" if ARM && !CPU_CACHE_VIPT | 
 | 	default "999999" if PARISC && !PA20 | 
 | 	default "4" | 
 |  | 
 | config ARCH_ENABLE_SPLIT_PMD_PTLOCK | 
 | 	bool | 
 |  | 
 | # | 
 | # support for memory balloon | 
 | config MEMORY_BALLOON | 
 | 	bool | 
 |  | 
 | # | 
 | # support for memory balloon compaction | 
 | config BALLOON_COMPACTION | 
 | 	bool "Allow for balloon memory compaction/migration" | 
 | 	def_bool y | 
 | 	depends on COMPACTION && MEMORY_BALLOON | 
 | 	help | 
 | 	  Memory fragmentation introduced by ballooning might reduce | 
 | 	  significantly the number of 2MB contiguous memory blocks that can be | 
 | 	  used within a guest, thus imposing performance penalties associated | 
 | 	  with the reduced number of transparent huge pages that could be used | 
 | 	  by the guest workload. Allowing the compaction & migration for memory | 
 | 	  pages enlisted as being part of memory balloon devices avoids the | 
 | 	  scenario aforementioned and helps improving memory defragmentation. | 
 |  | 
 | # | 
 | # support for memory compaction | 
 | config COMPACTION | 
 | 	bool "Allow for memory compaction" | 
 | 	def_bool y | 
 | 	select MIGRATION | 
 | 	depends on MMU | 
 | 	help | 
 |           Compaction is the only memory management component to form | 
 |           high order (larger physically contiguous) memory blocks | 
 |           reliably. The page allocator relies on compaction heavily and | 
 |           the lack of the feature can lead to unexpected OOM killer | 
 |           invocations for high order memory requests. You shouldn't | 
 |           disable this option unless there really is a strong reason for | 
 |           it and then we would be really interested to hear about that at | 
 |           linux-mm@kvack.org. | 
 |  | 
 | # | 
 | # support for page migration | 
 | # | 
 | config MIGRATION | 
 | 	bool "Page migration" | 
 | 	def_bool y | 
 | 	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU | 
 | 	help | 
 | 	  Allows the migration of the physical location of pages of processes | 
 | 	  while the virtual addresses are not changed. This is useful in | 
 | 	  two situations. The first is on NUMA systems to put pages nearer | 
 | 	  to the processors accessing. The second is when allocating huge | 
 | 	  pages as migration can relocate pages to satisfy a huge page | 
 | 	  allocation instead of reclaiming. | 
 |  | 
 | config ARCH_ENABLE_HUGEPAGE_MIGRATION | 
 | 	bool | 
 |  | 
 | config PHYS_ADDR_T_64BIT | 
 | 	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT | 
 |  | 
 | config BOUNCE | 
 | 	bool "Enable bounce buffers" | 
 | 	default y | 
 | 	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) | 
 | 	help | 
 | 	  Enable bounce buffers for devices that cannot access | 
 | 	  the full range of memory available to the CPU. Enabled | 
 | 	  by default when ZONE_DMA or HIGHMEM is selected, but you | 
 | 	  may say n to override this. | 
 |  | 
 | # On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often | 
 | # have more than 4GB of memory, but we don't currently use the IOTLB to present | 
 | # a 32-bit address to OHCI.  So we need to use a bounce pool instead. | 
 | config NEED_BOUNCE_POOL | 
 | 	bool | 
 | 	default y if TILE && USB_OHCI_HCD | 
 |  | 
 | config NR_QUICK | 
 | 	int | 
 | 	depends on QUICKLIST | 
 | 	default "2" if AVR32 | 
 | 	default "1" | 
 |  | 
 | config VIRT_TO_BUS | 
 | 	bool | 
 | 	help | 
 | 	  An architecture should select this if it implements the | 
 | 	  deprecated interface virt_to_bus().  All new architectures | 
 | 	  should probably not select this. | 
 |  | 
 |  | 
 | config MMU_NOTIFIER | 
 | 	bool | 
 | 	select SRCU | 
 |  | 
 | config KSM | 
 | 	bool "Enable KSM for page merging" | 
 | 	depends on MMU | 
 | 	help | 
 | 	  Enable Kernel Samepage Merging: KSM periodically scans those areas | 
 | 	  of an application's address space that an app has advised may be | 
 | 	  mergeable.  When it finds pages of identical content, it replaces | 
 | 	  the many instances by a single page with that content, so | 
 | 	  saving memory until one or another app needs to modify the content. | 
 | 	  Recommended for use with KVM, or with other duplicative applications. | 
 | 	  See Documentation/vm/ksm.txt for more information: KSM is inactive | 
 | 	  until a program has madvised that an area is MADV_MERGEABLE, and | 
 | 	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). | 
 |  | 
 | config DEFAULT_MMAP_MIN_ADDR | 
 |         int "Low address space to protect from user allocation" | 
 | 	depends on MMU | 
 |         default 4096 | 
 |         help | 
 | 	  This is the portion of low virtual memory which should be protected | 
 | 	  from userspace allocation.  Keeping a user from writing to low pages | 
 | 	  can help reduce the impact of kernel NULL pointer bugs. | 
 |  | 
 | 	  For most ia64, ppc64 and x86 users with lots of address space | 
 | 	  a value of 65536 is reasonable and should cause no problems. | 
 | 	  On arm and other archs it should not be higher than 32768. | 
 | 	  Programs which use vm86 functionality or have some need to map | 
 | 	  this low address space will need CAP_SYS_RAWIO or disable this | 
 | 	  protection by setting the value to 0. | 
 |  | 
 | 	  This value can be changed after boot using the | 
 | 	  /proc/sys/vm/mmap_min_addr tunable. | 
 |  | 
 | config ARCH_SUPPORTS_MEMORY_FAILURE | 
 | 	bool | 
 |  | 
 | config MEMORY_FAILURE | 
 | 	depends on MMU | 
 | 	depends on ARCH_SUPPORTS_MEMORY_FAILURE | 
 | 	bool "Enable recovery from hardware memory errors" | 
 | 	select MEMORY_ISOLATION | 
 | 	select RAS | 
 | 	help | 
 | 	  Enables code to recover from some memory failures on systems | 
 | 	  with MCA recovery. This allows a system to continue running | 
 | 	  even when some of its memory has uncorrected errors. This requires | 
 | 	  special hardware support and typically ECC memory. | 
 |  | 
 | config HWPOISON_INJECT | 
 | 	tristate "HWPoison pages injector" | 
 | 	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS | 
 | 	select PROC_PAGE_MONITOR | 
 |  | 
 | config NOMMU_INITIAL_TRIM_EXCESS | 
 | 	int "Turn on mmap() excess space trimming before booting" | 
 | 	depends on !MMU | 
 | 	default 1 | 
 | 	help | 
 | 	  The NOMMU mmap() frequently needs to allocate large contiguous chunks | 
 | 	  of memory on which to store mappings, but it can only ask the system | 
 | 	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently | 
 | 	  more than it requires.  To deal with this, mmap() is able to trim off | 
 | 	  the excess and return it to the allocator. | 
 |  | 
 | 	  If trimming is enabled, the excess is trimmed off and returned to the | 
 | 	  system allocator, which can cause extra fragmentation, particularly | 
 | 	  if there are a lot of transient processes. | 
 |  | 
 | 	  If trimming is disabled, the excess is kept, but not used, which for | 
 | 	  long-term mappings means that the space is wasted. | 
 |  | 
 | 	  Trimming can be dynamically controlled through a sysctl option | 
 | 	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of | 
 | 	  excess pages there must be before trimming should occur, or zero if | 
 | 	  no trimming is to occur. | 
 |  | 
 | 	  This option specifies the initial value of this option.  The default | 
 | 	  of 1 says that all excess pages should be trimmed. | 
 |  | 
 | 	  See Documentation/nommu-mmap.txt for more information. | 
 |  | 
 | config TRANSPARENT_HUGEPAGE | 
 | 	bool "Transparent Hugepage Support" | 
 | 	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE | 
 | 	select COMPACTION | 
 | 	select RADIX_TREE_MULTIORDER | 
 | 	help | 
 | 	  Transparent Hugepages allows the kernel to use huge pages and | 
 | 	  huge tlb transparently to the applications whenever possible. | 
 | 	  This feature can improve computing performance to certain | 
 | 	  applications by speeding up page faults during memory | 
 | 	  allocation, by reducing the number of tlb misses and by speeding | 
 | 	  up the pagetable walking. | 
 |  | 
 | 	  If memory constrained on embedded, you may want to say N. | 
 |  | 
 | choice | 
 | 	prompt "Transparent Hugepage Support sysfs defaults" | 
 | 	depends on TRANSPARENT_HUGEPAGE | 
 | 	default TRANSPARENT_HUGEPAGE_ALWAYS | 
 | 	help | 
 | 	  Selects the sysfs defaults for Transparent Hugepage Support. | 
 |  | 
 | 	config TRANSPARENT_HUGEPAGE_ALWAYS | 
 | 		bool "always" | 
 | 	help | 
 | 	  Enabling Transparent Hugepage always, can increase the | 
 | 	  memory footprint of applications without a guaranteed | 
 | 	  benefit but it will work automatically for all applications. | 
 |  | 
 | 	config TRANSPARENT_HUGEPAGE_MADVISE | 
 | 		bool "madvise" | 
 | 	help | 
 | 	  Enabling Transparent Hugepage madvise, will only provide a | 
 | 	  performance improvement benefit to the applications using | 
 | 	  madvise(MADV_HUGEPAGE) but it won't risk to increase the | 
 | 	  memory footprint of applications without a guaranteed | 
 | 	  benefit. | 
 | endchoice | 
 |  | 
 | config	TRANSPARENT_HUGE_PAGECACHE | 
 | 	def_bool y | 
 | 	depends on TRANSPARENT_HUGEPAGE | 
 |  | 
 | # | 
 | # UP and nommu archs use km based percpu allocator | 
 | # | 
 | config NEED_PER_CPU_KM | 
 | 	depends on !SMP | 
 | 	bool | 
 | 	default y | 
 |  | 
 | config CLEANCACHE | 
 | 	bool "Enable cleancache driver to cache clean pages if tmem is present" | 
 | 	default n | 
 | 	help | 
 | 	  Cleancache can be thought of as a page-granularity victim cache | 
 | 	  for clean pages that the kernel's pageframe replacement algorithm | 
 | 	  (PFRA) would like to keep around, but can't since there isn't enough | 
 | 	  memory.  So when the PFRA "evicts" a page, it first attempts to use | 
 | 	  cleancache code to put the data contained in that page into | 
 | 	  "transcendent memory", memory that is not directly accessible or | 
 | 	  addressable by the kernel and is of unknown and possibly | 
 | 	  time-varying size.  And when a cleancache-enabled | 
 | 	  filesystem wishes to access a page in a file on disk, it first | 
 | 	  checks cleancache to see if it already contains it; if it does, | 
 | 	  the page is copied into the kernel and a disk access is avoided. | 
 | 	  When a transcendent memory driver is available (such as zcache or | 
 | 	  Xen transcendent memory), a significant I/O reduction | 
 | 	  may be achieved.  When none is available, all cleancache calls | 
 | 	  are reduced to a single pointer-compare-against-NULL resulting | 
 | 	  in a negligible performance hit. | 
 |  | 
 | 	  If unsure, say Y to enable cleancache | 
 |  | 
 | config FRONTSWAP | 
 | 	bool "Enable frontswap to cache swap pages if tmem is present" | 
 | 	depends on SWAP | 
 | 	default n | 
 | 	help | 
 | 	  Frontswap is so named because it can be thought of as the opposite | 
 | 	  of a "backing" store for a swap device.  The data is stored into | 
 | 	  "transcendent memory", memory that is not directly accessible or | 
 | 	  addressable by the kernel and is of unknown and possibly | 
 | 	  time-varying size.  When space in transcendent memory is available, | 
 | 	  a significant swap I/O reduction may be achieved.  When none is | 
 | 	  available, all frontswap calls are reduced to a single pointer- | 
 | 	  compare-against-NULL resulting in a negligible performance hit | 
 | 	  and swap data is stored as normal on the matching swap device. | 
 |  | 
 | 	  If unsure, say Y to enable frontswap. | 
 |  | 
 | config CMA | 
 | 	bool "Contiguous Memory Allocator" | 
 | 	depends on HAVE_MEMBLOCK && MMU | 
 | 	select MIGRATION | 
 | 	select MEMORY_ISOLATION | 
 | 	help | 
 | 	  This enables the Contiguous Memory Allocator which allows other | 
 | 	  subsystems to allocate big physically-contiguous blocks of memory. | 
 | 	  CMA reserves a region of memory and allows only movable pages to | 
 | 	  be allocated from it. This way, the kernel can use the memory for | 
 | 	  pagecache and when a subsystem requests for contiguous area, the | 
 | 	  allocated pages are migrated away to serve the contiguous request. | 
 |  | 
 | 	  If unsure, say "n". | 
 |  | 
 | config CMA_DEBUG | 
 | 	bool "CMA debug messages (DEVELOPMENT)" | 
 | 	depends on DEBUG_KERNEL && CMA | 
 | 	help | 
 | 	  Turns on debug messages in CMA.  This produces KERN_DEBUG | 
 | 	  messages for every CMA call as well as various messages while | 
 | 	  processing calls such as dma_alloc_from_contiguous(). | 
 | 	  This option does not affect warning and error messages. | 
 |  | 
 | config CMA_DEBUGFS | 
 | 	bool "CMA debugfs interface" | 
 | 	depends on CMA && DEBUG_FS | 
 | 	help | 
 | 	  Turns on the DebugFS interface for CMA. | 
 |  | 
 | config CMA_AREAS | 
 | 	int "Maximum count of the CMA areas" | 
 | 	depends on CMA | 
 | 	default 7 | 
 | 	help | 
 | 	  CMA allows to create CMA areas for particular purpose, mainly, | 
 | 	  used as device private area. This parameter sets the maximum | 
 | 	  number of CMA area in the system. | 
 |  | 
 | 	  If unsure, leave the default value "7". | 
 |  | 
 | config MEM_SOFT_DIRTY | 
 | 	bool "Track memory changes" | 
 | 	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS | 
 | 	select PROC_PAGE_MONITOR | 
 | 	help | 
 | 	  This option enables memory changes tracking by introducing a | 
 | 	  soft-dirty bit on pte-s. This bit it set when someone writes | 
 | 	  into a page just as regular dirty bit, but unlike the latter | 
 | 	  it can be cleared by hands. | 
 |  | 
 | 	  See Documentation/vm/soft-dirty.txt for more details. | 
 |  | 
 | config ZSWAP | 
 | 	bool "Compressed cache for swap pages (EXPERIMENTAL)" | 
 | 	depends on FRONTSWAP && CRYPTO=y | 
 | 	select CRYPTO_LZO | 
 | 	select ZPOOL | 
 | 	default n | 
 | 	help | 
 | 	  A lightweight compressed cache for swap pages.  It takes | 
 | 	  pages that are in the process of being swapped out and attempts to | 
 | 	  compress them into a dynamically allocated RAM-based memory pool. | 
 | 	  This can result in a significant I/O reduction on swap device and, | 
 | 	  in the case where decompressing from RAM is faster that swap device | 
 | 	  reads, can also improve workload performance. | 
 |  | 
 | 	  This is marked experimental because it is a new feature (as of | 
 | 	  v3.11) that interacts heavily with memory reclaim.  While these | 
 | 	  interactions don't cause any known issues on simple memory setups, | 
 | 	  they have not be fully explored on the large set of potential | 
 | 	  configurations and workloads that exist. | 
 |  | 
 | config ZPOOL | 
 | 	tristate "Common API for compressed memory storage" | 
 | 	default n | 
 | 	help | 
 | 	  Compressed memory storage API.  This allows using either zbud or | 
 | 	  zsmalloc. | 
 |  | 
 | config ZBUD | 
 | 	tristate "Low (Up to 2x) density storage for compressed pages" | 
 | 	default n | 
 | 	help | 
 | 	  A special purpose allocator for storing compressed pages. | 
 | 	  It is designed to store up to two compressed pages per physical | 
 | 	  page.  While this design limits storage density, it has simple and | 
 | 	  deterministic reclaim properties that make it preferable to a higher | 
 | 	  density approach when reclaim will be used. | 
 |  | 
 | config Z3FOLD | 
 | 	tristate "Up to 3x density storage for compressed pages" | 
 | 	depends on ZPOOL | 
 | 	default n | 
 | 	help | 
 | 	  A special purpose allocator for storing compressed pages. | 
 | 	  It is designed to store up to three compressed pages per physical | 
 | 	  page. It is a ZBUD derivative so the simplicity and determinism are | 
 | 	  still there. | 
 |  | 
 | config ZSMALLOC | 
 | 	tristate "Memory allocator for compressed pages" | 
 | 	depends on MMU | 
 | 	default n | 
 | 	help | 
 | 	  zsmalloc is a slab-based memory allocator designed to store | 
 | 	  compressed RAM pages.  zsmalloc uses virtual memory mapping | 
 | 	  in order to reduce fragmentation.  However, this results in a | 
 | 	  non-standard allocator interface where a handle, not a pointer, is | 
 | 	  returned by an alloc().  This handle must be mapped in order to | 
 | 	  access the allocated space. | 
 |  | 
 | config PGTABLE_MAPPING | 
 | 	bool "Use page table mapping to access object in zsmalloc" | 
 | 	depends on ZSMALLOC | 
 | 	help | 
 | 	  By default, zsmalloc uses a copy-based object mapping method to | 
 | 	  access allocations that span two pages. However, if a particular | 
 | 	  architecture (ex, ARM) performs VM mapping faster than copying, | 
 | 	  then you should select this. This causes zsmalloc to use page table | 
 | 	  mapping rather than copying for object mapping. | 
 |  | 
 | 	  You can check speed with zsmalloc benchmark: | 
 | 	  https://github.com/spartacus06/zsmapbench | 
 |  | 
 | config ZSMALLOC_STAT | 
 | 	bool "Export zsmalloc statistics" | 
 | 	depends on ZSMALLOC | 
 | 	select DEBUG_FS | 
 | 	help | 
 | 	  This option enables code in the zsmalloc to collect various | 
 | 	  statistics about whats happening in zsmalloc and exports that | 
 | 	  information to userspace via debugfs. | 
 | 	  If unsure, say N. | 
 |  | 
 | config GENERIC_EARLY_IOREMAP | 
 | 	bool | 
 |  | 
 | config MAX_STACK_SIZE_MB | 
 | 	int "Maximum user stack size for 32-bit processes (MB)" | 
 | 	default 80 | 
 | 	range 8 256 if METAG | 
 | 	range 8 2048 | 
 | 	depends on STACK_GROWSUP && (!64BIT || COMPAT) | 
 | 	help | 
 | 	  This is the maximum stack size in Megabytes in the VM layout of 32-bit | 
 | 	  user processes when the stack grows upwards (currently only on parisc | 
 | 	  and metag arch). The stack will be located at the highest memory | 
 | 	  address minus the given value, unless the RLIMIT_STACK hard limit is | 
 | 	  changed to a smaller value in which case that is used. | 
 |  | 
 | 	  A sane initial value is 80 MB. | 
 |  | 
 | # For architectures that support deferred memory initialisation | 
 | config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT | 
 | 	bool | 
 |  | 
 | config DEFERRED_STRUCT_PAGE_INIT | 
 | 	bool "Defer initialisation of struct pages to kthreads" | 
 | 	default n | 
 | 	depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT | 
 | 	depends on NO_BOOTMEM && MEMORY_HOTPLUG | 
 | 	depends on !FLATMEM | 
 | 	help | 
 | 	  Ordinarily all struct pages are initialised during early boot in a | 
 | 	  single thread. On very large machines this can take a considerable | 
 | 	  amount of time. If this option is set, large machines will bring up | 
 | 	  a subset of memmap at boot and then initialise the rest in parallel | 
 | 	  by starting one-off "pgdatinitX" kernel thread for each node X. This | 
 | 	  has a potential performance impact on processes running early in the | 
 | 	  lifetime of the system until these kthreads finish the | 
 | 	  initialisation. | 
 |  | 
 | config IDLE_PAGE_TRACKING | 
 | 	bool "Enable idle page tracking" | 
 | 	depends on SYSFS && MMU | 
 | 	select PAGE_EXTENSION if !64BIT | 
 | 	help | 
 | 	  This feature allows to estimate the amount of user pages that have | 
 | 	  not been touched during a given period of time. This information can | 
 | 	  be useful to tune memory cgroup limits and/or for job placement | 
 | 	  within a compute cluster. | 
 |  | 
 | 	  See Documentation/vm/idle_page_tracking.txt for more details. | 
 |  | 
 | config ZONE_DEVICE | 
 | 	bool "Device memory (pmem, etc...) hotplug support" | 
 | 	depends on MEMORY_HOTPLUG | 
 | 	depends on MEMORY_HOTREMOVE | 
 | 	depends on SPARSEMEM_VMEMMAP | 
 | 	depends on X86_64 #arch_add_memory() comprehends device memory | 
 |  | 
 | 	help | 
 | 	  Device memory hotplug support allows for establishing pmem, | 
 | 	  or other device driver discovered memory regions, in the | 
 | 	  memmap. This allows pfn_to_page() lookups of otherwise | 
 | 	  "device-physical" addresses which is needed for using a DAX | 
 | 	  mapping in an O_DIRECT operation, among other things. | 
 |  | 
 | 	  If FS_DAX is enabled, then say Y. | 
 |  | 
 | config FRAME_VECTOR | 
 | 	bool | 
 |  | 
 | config ARCH_USES_HIGH_VMA_FLAGS | 
 | 	bool | 
 | config ARCH_HAS_PKEYS | 
 | 	bool |