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Dave Hansene1785e82005-06-23 00:07:49 -07001config SELECT_MEMORY_MODEL
2 def_bool y
3 depends on EXPERIMENTAL || ARCH_SELECT_MEMORY_MODEL
4
Dave Hansen3a9da762005-06-23 00:07:42 -07005choice
6 prompt "Memory model"
Dave Hansene1785e82005-06-23 00:07:49 -07007 depends on SELECT_MEMORY_MODEL
8 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
Andy Whitcroftd41dee32005-06-23 00:07:54 -07009 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
Dave Hansene1785e82005-06-23 00:07:49 -070010 default FLATMEM_MANUAL
Dave Hansen3a9da762005-06-23 00:07:42 -070011
Dave Hansene1785e82005-06-23 00:07:49 -070012config FLATMEM_MANUAL
Dave Hansen3a9da762005-06-23 00:07:42 -070013 bool "Flat Memory"
Anton Blanchardc898ec12006-01-06 00:12:07 -080014 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
Dave Hansen3a9da762005-06-23 00:07:42 -070015 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
Andy Whitcroftd41dee32005-06-23 00:07:54 -070021 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.
Dave Hansen3a9da762005-06-23 00:07:42 -070030
Dave Hansene1785e82005-06-23 00:07:49 -070031config DISCONTIGMEM_MANUAL
Dave Hansenf3519f92005-09-16 19:27:54 -070032 bool "Discontiguous Memory"
Dave Hansen3a9da762005-06-23 00:07:42 -070033 depends on ARCH_DISCONTIGMEM_ENABLE
34 help
Dave Hansen785dcd42005-06-23 00:07:50 -070035 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
Philipp Marekad3d0a32007-10-20 02:46:58 +020040 can have degraded performance from the extra overhead that
Dave Hansen785dcd42005-06-23 00:07:50 -070041 this option imposes.
42
43 Many NUMA configurations will have this as the only option.
44
Dave Hansen3a9da762005-06-23 00:07:42 -070045 If unsure, choose "Flat Memory" over this option.
46
Andy Whitcroftd41dee32005-06-23 00:07:54 -070047config 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
Dave Hansenf3519f92005-09-16 19:27:54 -070055 "Discontiguous Memory". This option provides some potential
Andy Whitcroftd41dee32005-06-23 00:07:54 -070056 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
Dave Hansen3a9da762005-06-23 00:07:42 -070062endchoice
63
Dave Hansene1785e82005-06-23 00:07:49 -070064config DISCONTIGMEM
65 def_bool y
66 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
67
Andy Whitcroftd41dee32005-06-23 00:07:54 -070068config SPARSEMEM
69 def_bool y
Russell King1a83e172009-10-26 16:50:12 -070070 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
Andy Whitcroftd41dee32005-06-23 00:07:54 -070071
Dave Hansene1785e82005-06-23 00:07:49 -070072config FLATMEM
73 def_bool y
Andy Whitcroftd41dee32005-06-23 00:07:54 -070074 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
75
76config FLAT_NODE_MEM_MAP
77 def_bool y
78 depends on !SPARSEMEM
Dave Hansene1785e82005-06-23 00:07:49 -070079
Dave Hansen93b75042005-06-23 00:07:47 -070080#
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
Andy Whitcroftaf705362005-06-23 00:07:53 -070088
89config HAVE_MEMORY_PRESENT
90 def_bool y
Andy Whitcroftd41dee32005-06-23 00:07:54 -070091 depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
Bob Picco802f1922005-09-03 15:54:26 -070092
93#
Bob Picco3e347262005-09-03 15:54:28 -070094# SPARSEMEM_EXTREME (which is the default) does some bootmem
Matt LaPlante84eb8d02006-10-03 22:53:09 +020095# allocations when memory_present() is called. If this cannot
Bob Picco3e347262005-09-03 15:54:28 -070096# 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
Jan Beulich9ba16082008-10-15 22:01:38 -0700104 bool
Bob Picco3e347262005-09-03 15:54:28 -0700105
106#
Matt LaPlante44c09202006-10-03 22:34:14 +0200107# Architecture platforms which require a two level mem_section in SPARSEMEM
Bob Picco802f1922005-09-03 15:54:26 -0700108# must select this option. This is usually for architecture platforms with
109# an extremely sparse physical address space.
110#
Bob Picco3e347262005-09-03 15:54:28 -0700111config SPARSEMEM_EXTREME
112 def_bool y
113 depends on SPARSEMEM && !SPARSEMEM_STATIC
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700114
Andy Whitcroft29c71112007-10-16 01:24:14 -0700115config SPARSEMEM_VMEMMAP_ENABLE
Jan Beulich9ba16082008-10-15 22:01:38 -0700116 bool
Andy Whitcroft29c71112007-10-16 01:24:14 -0700117
Yinghai Lu9bdac912010-02-10 01:20:22 -0800118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119 def_bool y
120 depends on SPARSEMEM && X86_64
121
Andy Whitcroft29c71112007-10-16 01:24:14 -0700122config SPARSEMEM_VMEMMAP
Geoff Levanda5ee6da2007-12-17 16:19:53 -0800123 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.
Andy Whitcroft29c71112007-10-16 01:24:14 -0700130
Yinghai Lu95f72d12010-07-12 14:36:09 +1000131config HAVE_MEMBLOCK
132 boolean
133
Tejun Heo7c0caeb2011-07-14 11:43:42 +0200134config HAVE_MEMBLOCK_NODE_MAP
135 boolean
136
Tejun Heoc378ddd2011-07-14 11:46:03 +0200137config ARCH_DISCARD_MEMBLOCK
138 boolean
139
Sam Ravnborg66616722011-10-31 17:08:20 -0700140config NO_BOOTMEM
141 boolean
142
Dave Hansen3947be12005-10-29 18:16:54 -0700143# eventually, we can have this option just 'select SPARSEMEM'
144config MEMORY_HOTPLUG
145 bool "Allow for memory hot-add"
Keith Manntheyec69acb2006-09-30 23:27:05 -0700146 depends on SPARSEMEM || X86_64_ACPI_NUMA
Andi Kleen6ad696d2009-11-17 14:06:22 -0800147 depends on HOTPLUG && ARCH_ENABLE_MEMORY_HOTPLUG
Kumar Galaed84a072009-10-16 07:21:36 +0000148 depends on (IA64 || X86 || PPC_BOOK3S_64 || SUPERH || S390)
Dave Hansen3947be12005-10-29 18:16:54 -0700149
Keith Manntheyec69acb2006-09-30 23:27:05 -0700150config MEMORY_HOTPLUG_SPARSE
151 def_bool y
152 depends on SPARSEMEM && MEMORY_HOTPLUG
153
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700154config MEMORY_HOTREMOVE
155 bool "Allow for memory hot remove"
156 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
157 depends on MIGRATION
158
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700159#
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
H. Peter Anvina269cca2009-08-31 11:17:44 -0700169 depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700170
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700171# 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.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800176# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800177# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700178#
179config SPLIT_PTLOCK_CPUS
180 int
Hugh Dickinsa70caa82009-12-14 17:59:02 -0800181 default "999999" if ARM && !CPU_CACHE_VIPT
182 default "999999" if PARISC && !PA20
183 default "999999" if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700184 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800185
186#
Mel Gormane9e96b32010-05-24 14:32:21 -0700187# support for memory compaction
188config COMPACTION
189 bool "Allow for memory compaction"
190 select MIGRATION
Andrea Arcangeli33a93872011-01-25 15:07:25 -0800191 depends on MMU
Mel Gormane9e96b32010-05-24 14:32:21 -0700192 help
193 Allows the compaction of memory for the allocation of huge pages.
194
195#
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800196# support for page migration
197#
198config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800199 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700200 def_bool y
Michal Nazarewicz47118af2011-12-29 13:09:50 +0100201 depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA
Christoph Lameterb20a3502006-03-22 00:09:12 -0800202 help
203 Allows the migration of the physical location of pages of processes
Mel Gormane9e96b32010-05-24 14:32:21 -0700204 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.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700209
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700210config PHYS_ADDR_T_64BIT
211 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
212
Christoph Lameter4b51d662007-02-10 01:43:10 -0800213config ZONE_DMA_FLAG
214 int
215 default "0" if !ZONE_DMA
216 default "1"
217
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700218config BOUNCE
219 def_bool y
220 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
221
Christoph Lameter6225e932007-05-06 14:49:50 -0700222config NR_QUICK
223 int
224 depends on QUICKLIST
Paul Mundt0176bd32010-01-05 12:35:00 +0900225 default "2" if AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700226 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700227
228config VIRT_TO_BUS
229 def_bool y
230 depends on !ARCH_NO_VIRT_TO_BUS
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700231
232config MMU_NOTIFIER
233 bool
David Howellsfc4d5c22009-05-06 16:03:05 -0700234
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700235config 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
Hugh Dickinsd0f209f2009-12-14 17:59:34 -0800242 the many instances by a single page with that content, so
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700243 saving memory until one or another app needs to modify the content.
244 Recommended for use with KVM, or with other duplicative applications.
Hugh Dickinsc73602a2009-10-07 16:32:22 -0700245 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).
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700248
Christoph Lametere0a94c22009-06-03 16:04:31 -0400249config DEFAULT_MMAP_MIN_ADDR
250 int "Low address space to protect from user allocation"
David Howells6e141542009-12-15 19:27:45 +0000251 depends on MMU
Christoph Lametere0a94c22009-06-03 16:04:31 -0400252 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.
Eric Paris788084a2009-07-31 12:54:11 -0400261 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.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400264
265 This value can be changed after boot using the
266 /proc/sys/vm/mmap_min_addr tunable.
267
Linus Torvaldsd949f362009-09-26 09:35:07 -0700268config ARCH_SUPPORTS_MEMORY_FAILURE
269 bool
Christoph Lametere0a94c22009-06-03 16:04:31 -0400270
Andi Kleen6a460792009-09-16 11:50:15 +0200271config MEMORY_FAILURE
272 depends on MMU
Linus Torvaldsd949f362009-09-26 09:35:07 -0700273 depends on ARCH_SUPPORTS_MEMORY_FAILURE
Andi Kleen6a460792009-09-16 11:50:15 +0200274 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
Andi Kleencae681f2009-09-16 11:50:17 +0200281config HWPOISON_INJECT
Andi Kleen413f9ef2009-12-16 12:20:00 +0100282 tristate "HWPoison pages injector"
Andi Kleen27df5062009-12-21 19:56:42 +0100283 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
Wu Fengguang478c5ff2009-12-16 12:19:59 +0100284 select PROC_PAGE_MONITOR
Andi Kleencae681f2009-09-16 11:50:17 +0200285
David Howellsfc4d5c22009-05-06 16:03:05 -0700286config 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.
Tejun Heobbddff02010-09-03 18:22:48 +0200313
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800314config TRANSPARENT_HUGEPAGE
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800315 bool "Transparent Hugepage Support"
Johannes Weinerf2d6bfe2011-01-13 15:47:01 -0800316 depends on X86 && MMU
Andrea Arcangeli5d689242011-01-13 15:47:07 -0800317 select COMPACTION
Andrea Arcangeli4c76d9d2011-01-13 15:46:39 -0800318 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
Andrea Arcangeli13ece882011-01-13 15:47:07 -0800328choice
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
Christopher Yeoh5febcbe2012-05-29 15:06:27 -0700352config CROSS_MEMORY_ATTACH
353 bool "Cross Memory Support"
354 depends on MMU
355 default y
356 help
357 Enabling this option adds the system calls process_vm_readv and
358 process_vm_writev which allow a process with the correct privileges
359 to directly read from or write to to another process's address space.
360 See the man page for more details.
361
Tejun Heobbddff02010-09-03 18:22:48 +0200362#
363# UP and nommu archs use km based percpu allocator
364#
365config NEED_PER_CPU_KM
366 depends on !SMP
367 bool
368 default y
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600369
370config CLEANCACHE
371 bool "Enable cleancache driver to cache clean pages if tmem is present"
372 default n
373 help
374 Cleancache can be thought of as a page-granularity victim cache
375 for clean pages that the kernel's pageframe replacement algorithm
376 (PFRA) would like to keep around, but can't since there isn't enough
377 memory. So when the PFRA "evicts" a page, it first attempts to use
Michael Witten140a1ef2011-06-10 03:57:26 +0000378 cleancache code to put the data contained in that page into
Dan Magenheimer077b1f82011-05-26 10:01:36 -0600379 "transcendent memory", memory that is not directly accessible or
380 addressable by the kernel and is of unknown and possibly
381 time-varying size. And when a cleancache-enabled
382 filesystem wishes to access a page in a file on disk, it first
383 checks cleancache to see if it already contains it; if it does,
384 the page is copied into the kernel and a disk access is avoided.
385 When a transcendent memory driver is available (such as zcache or
386 Xen transcendent memory), a significant I/O reduction
387 may be achieved. When none is available, all cleancache calls
388 are reduced to a single pointer-compare-against-NULL resulting
389 in a negligible performance hit.
390
391 If unsure, say Y to enable cleancache
Dan Magenheimer27c6aec2012-04-09 17:10:34 -0600392
393config FRONTSWAP
394 bool "Enable frontswap to cache swap pages if tmem is present"
395 depends on SWAP
396 default n
397 help
398 Frontswap is so named because it can be thought of as the opposite
399 of a "backing" store for a swap device. The data is stored into
400 "transcendent memory", memory that is not directly accessible or
401 addressable by the kernel and is of unknown and possibly
402 time-varying size. When space in transcendent memory is available,
403 a significant swap I/O reduction may be achieved. When none is
404 available, all frontswap calls are reduced to a single pointer-
405 compare-against-NULL resulting in a negligible performance hit
406 and swap data is stored as normal on the matching swap device.
407
408 If unsure, say Y to enable frontswap.