1config SELECT_MEMORY_MODEL
2	def_bool y
3	depends on EXPERIMENTAL || ARCH_SELECT_MEMORY_MODEL
4
5choice
6	prompt "Memory model"
7	depends on SELECT_MEMORY_MODEL
8	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
9	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
10	default FLATMEM_MANUAL
11
12config FLATMEM_MANUAL
13	bool "Flat Memory"
14	depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
15	help
16	  This option allows you to change some of the ways that
17	  Linux manages its memory internally.  Most users will
18	  only have one option here: FLATMEM.  This is normal
19	  and a correct option.
20
21	  Some users of more advanced features like NUMA and
22	  memory hotplug may have different options here.
23	  DISCONTIGMEM is an more mature, better tested system,
24	  but is incompatible with memory hotplug and may suffer
25	  decreased performance over SPARSEMEM.  If unsure between
26	  "Sparse Memory" and "Discontiguous Memory", choose
27	  "Discontiguous Memory".
28
29	  If unsure, choose this option (Flat Memory) over any other.
30
31config DISCONTIGMEM_MANUAL
32	bool "Discontiguous Memory"
33	depends on ARCH_DISCONTIGMEM_ENABLE
34	help
35	  This option provides enhanced support for discontiguous
36	  memory systems, over FLATMEM.  These systems have holes
37	  in their physical address spaces, and this option provides
38	  more efficient handling of these holes.  However, the vast
39	  majority of hardware has quite flat address spaces, and
40	  can have degraded performance from the extra overhead that
41	  this option imposes.
42
43	  Many NUMA configurations will have this as the only option.
44
45	  If unsure, choose "Flat Memory" over this option.
46
47config SPARSEMEM_MANUAL
48	bool "Sparse Memory"
49	depends on ARCH_SPARSEMEM_ENABLE
50	help
51	  This will be the only option for some systems, including
52	  memory hotplug systems.  This is normal.
53
54	  For many other systems, this will be an alternative to
55	  "Discontiguous Memory".  This option provides some potential
56	  performance benefits, along with decreased code complexity,
57	  but it is newer, and more experimental.
58
59	  If unsure, choose "Discontiguous Memory" or "Flat Memory"
60	  over this option.
61
62endchoice
63
64config DISCONTIGMEM
65	def_bool y
66	depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
67
68config SPARSEMEM
69	def_bool y
70	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
71
72config FLATMEM
73	def_bool y
74	depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
75
76config FLAT_NODE_MEM_MAP
77	def_bool y
78	depends on !SPARSEMEM
79
80#
81# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
82# to represent different areas of memory.  This variable allows
83# those dependencies to exist individually.
84#
85config NEED_MULTIPLE_NODES
86	def_bool y
87	depends on DISCONTIGMEM || NUMA
88
89config HAVE_MEMORY_PRESENT
90	def_bool y
91	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
92
93#
94# SPARSEMEM_EXTREME (which is the default) does some bootmem
95# allocations when memory_present() is called.  If this cannot
96# be done on your architecture, select this option.  However,
97# statically allocating the mem_section[] array can potentially
98# consume vast quantities of .bss, so be careful.
99#
100# This option will also potentially produce smaller runtime code
101# with gcc 3.4 and later.
102#
103config SPARSEMEM_STATIC
104	bool
105
106#
107# Architecture platforms which require a two level mem_section in SPARSEMEM
108# must select this option. This is usually for architecture platforms with
109# an extremely sparse physical address space.
110#
111config SPARSEMEM_EXTREME
112	def_bool y
113	depends on SPARSEMEM && !SPARSEMEM_STATIC
114
115config SPARSEMEM_VMEMMAP_ENABLE
116	bool
117
118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119	def_bool y
120	depends on SPARSEMEM && X86_64
121
122config SPARSEMEM_VMEMMAP
123	bool "Sparse Memory virtual memmap"
124	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
125	default y
126	help
127	 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
128	 pfn_to_page and page_to_pfn operations.  This is the most
129	 efficient option when sufficient kernel resources are available.
130
131config HAVE_MEMBLOCK
132	boolean
133
134config HAVE_MEMBLOCK_NODE_MAP
135	boolean
136
137config ARCH_DISCARD_MEMBLOCK
138	boolean
139
140config NO_BOOTMEM
141	boolean
142
143# eventually, we can have this option just 'select SPARSEMEM'
144config MEMORY_HOTPLUG
145	bool "Allow for memory hot-add"
146	depends on SPARSEMEM || X86_64_ACPI_NUMA
147	depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
148	depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
149
150config MEMORY_HOTPLUG_SPARSE
151	def_bool y
152	depends on SPARSEMEM && MEMORY_HOTPLUG
153
154config MEMORY_HOTREMOVE
155	bool "Allow for memory hot remove"
156	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
157	depends on MIGRATION
158
159#
160# If we have space for more page flags then we can enable additional
161# optimizations and functionality.
162#
163# Regular Sparsemem takes page flag bits for the sectionid if it does not
164# use a virtual memmap. Disable extended page flags for 32 bit platforms
165# that require the use of a sectionid in the page flags.
166#
167config PAGEFLAGS_EXTENDED
168	def_bool y
169	depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
170
171# Heavily threaded applications may benefit from splitting the mm-wide
172# page_table_lock, so that faults on different parts of the user address
173# space can be handled with less contention: split it at this NR_CPUS.
174# Default to 4 for wider testing, though 8 might be more appropriate.
175# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
176# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
177# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
178#
179config SPLIT_PTLOCK_CPUS
180	int
181	default "999999" if ARM && !CPU_CACHE_VIPT
182	default "999999" if PARISC && !PA20
183	default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC
184	default "4"
185
186#
187# support for memory compaction
188config COMPACTION
189	bool "Allow for memory compaction"
190	select MIGRATION
191	depends on MMU
192	help
193	  Allows the compaction of memory for the allocation of huge pages.
194
195#
196# support for page migration
197#
198config MIGRATION
199	bool "Page migration"
200	def_bool y
201	depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION
202	help
203	  Allows the migration of the physical location of pages of processes
204	  while the virtual addresses are not changed. This is useful in
205	  two situations. The first is on NUMA systems to put pages nearer
206	  to the processors accessing. The second is when allocating huge
207	  pages as migration can relocate pages to satisfy a huge page
208	  allocation instead of reclaiming.
209
210config PHYS_ADDR_T_64BIT
211	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
212
213config ZONE_DMA_FLAG
214	int
215	default "0" if !ZONE_DMA
216	default "1"
217
218config BOUNCE
219	def_bool y
220	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
221
222config NR_QUICK
223	int
224	depends on QUICKLIST
225	default "2" if AVR32
226	default "1"
227
228config VIRT_TO_BUS
229	def_bool y
230	depends on !ARCH_NO_VIRT_TO_BUS
231
232config MMU_NOTIFIER
233	bool
234
235config KSM
236	bool "Enable KSM for page merging"
237	depends on MMU
238	help
239	  Enable Kernel Samepage Merging: KSM periodically scans those areas
240	  of an application's address space that an app has advised may be
241	  mergeable.  When it finds pages of identical content, it replaces
242	  the many instances by a single page with that content, so
243	  saving memory until one or another app needs to modify the content.
244	  Recommended for use with KVM, or with other duplicative applications.
245	  See Documentation/vm/ksm.txt for more information: KSM is inactive
246	  until a program has madvised that an area is MADV_MERGEABLE, and
247	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
248
249config DEFAULT_MMAP_MIN_ADDR
250        int "Low address space to protect from user allocation"
251	depends on MMU
252        default 4096
253        help
254	  This is the portion of low virtual memory which should be protected
255	  from userspace allocation.  Keeping a user from writing to low pages
256	  can help reduce the impact of kernel NULL pointer bugs.
257
258	  For most ia64, ppc64 and x86 users with lots of address space
259	  a value of 65536 is reasonable and should cause no problems.
260	  On arm and other archs it should not be higher than 32768.
261	  Programs which use vm86 functionality or have some need to map
262	  this low address space will need CAP_SYS_RAWIO or disable this
263	  protection by setting the value to 0.
264
265	  This value can be changed after boot using the
266	  /proc/sys/vm/mmap_min_addr tunable.
267
268config ARCH_SUPPORTS_MEMORY_FAILURE
269	bool
270
271config MEMORY_FAILURE
272	depends on MMU
273	depends on ARCH_SUPPORTS_MEMORY_FAILURE
274	bool "Enable recovery from hardware memory errors"
275	help
276	  Enables code to recover from some memory failures on systems
277	  with MCA recovery. This allows a system to continue running
278	  even when some of its memory has uncorrected errors. This requires
279	  special hardware support and typically ECC memory.
280
281config HWPOISON_INJECT
282	tristate "HWPoison pages injector"
283	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
284	select PROC_PAGE_MONITOR
285
286config NOMMU_INITIAL_TRIM_EXCESS
287	int "Turn on mmap() excess space trimming before booting"
288	depends on !MMU
289	default 1
290	help
291	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
292	  of memory on which to store mappings, but it can only ask the system
293	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
294	  more than it requires.  To deal with this, mmap() is able to trim off
295	  the excess and return it to the allocator.
296
297	  If trimming is enabled, the excess is trimmed off and returned to the
298	  system allocator, which can cause extra fragmentation, particularly
299	  if there are a lot of transient processes.
300
301	  If trimming is disabled, the excess is kept, but not used, which for
302	  long-term mappings means that the space is wasted.
303
304	  Trimming can be dynamically controlled through a sysctl option
305	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
306	  excess pages there must be before trimming should occur, or zero if
307	  no trimming is to occur.
308
309	  This option specifies the initial value of this option.  The default
310	  of 1 says that all excess pages should be trimmed.
311
312	  See Documentation/nommu-mmap.txt for more information.
313
314config TRANSPARENT_HUGEPAGE
315	bool "Transparent Hugepage Support"
316	depends on X86 && MMU
317	select COMPACTION
318	help
319	  Transparent Hugepages allows the kernel to use huge pages and
320	  huge tlb transparently to the applications whenever possible.
321	  This feature can improve computing performance to certain
322	  applications by speeding up page faults during memory
323	  allocation, by reducing the number of tlb misses and by speeding
324	  up the pagetable walking.
325
326	  If memory constrained on embedded, you may want to say N.
327
328choice
329	prompt "Transparent Hugepage Support sysfs defaults"
330	depends on TRANSPARENT_HUGEPAGE
331	default TRANSPARENT_HUGEPAGE_ALWAYS
332	help
333	  Selects the sysfs defaults for Transparent Hugepage Support.
334
335	config TRANSPARENT_HUGEPAGE_ALWAYS
336		bool "always"
337	help
338	  Enabling Transparent Hugepage always, can increase the
339	  memory footprint of applications without a guaranteed
340	  benefit but it will work automatically for all applications.
341
342	config TRANSPARENT_HUGEPAGE_MADVISE
343		bool "madvise"
344	help
345	  Enabling Transparent Hugepage madvise, will only provide a
346	  performance improvement benefit to the applications using
347	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
348	  memory footprint of applications without a guaranteed
349	  benefit.
350endchoice
351
352#
353# UP and nommu archs use km based percpu allocator
354#
355config NEED_PER_CPU_KM
356	depends on !SMP
357	bool
358	default y
359
360config CLEANCACHE
361	bool "Enable cleancache driver to cache clean pages if tmem is present"
362	default n
363	help
364	  Cleancache can be thought of as a page-granularity victim cache
365	  for clean pages that the kernel's pageframe replacement algorithm
366	  (PFRA) would like to keep around, but can't since there isn't enough
367	  memory.  So when the PFRA "evicts" a page, it first attempts to use
368	  cleancache code to put the data contained in that page into
369	  "transcendent memory", memory that is not directly accessible or
370	  addressable by the kernel and is of unknown and possibly
371	  time-varying size.  And when a cleancache-enabled
372	  filesystem wishes to access a page in a file on disk, it first
373	  checks cleancache to see if it already contains it; if it does,
374	  the page is copied into the kernel and a disk access is avoided.
375	  When a transcendent memory driver is available (such as zcache or
376	  Xen transcendent memory), a significant I/O reduction
377	  may be achieved.  When none is available, all cleancache calls
378	  are reduced to a single pointer-compare-against-NULL resulting
379	  in a negligible performance hit.
380
381	  If unsure, say Y to enable cleancache
382