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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
70 depends on SPARSEMEM_MANUAL
71
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
118config SPARSEMEM_VMEMMAP
Geoff Levanda5ee6da2007-12-17 16:19:53 -0800119 bool "Sparse Memory virtual memmap"
120 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
121 default y
122 help
123 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
124 pfn_to_page and page_to_pfn operations. This is the most
125 efficient option when sufficient kernel resources are available.
Andy Whitcroft29c71112007-10-16 01:24:14 -0700126
Dave Hansen3947be12005-10-29 18:16:54 -0700127# eventually, we can have this option just 'select SPARSEMEM'
128config MEMORY_HOTPLUG
129 bool "Allow for memory hot-add"
Keith Manntheyec69acb2006-09-30 23:27:05 -0700130 depends on SPARSEMEM || X86_64_ACPI_NUMA
Gerald Schaefer03997902009-06-16 10:30:48 +0200131 depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG
Heiko Carstens421c1752008-07-14 09:59:18 +0200132 depends on (IA64 || X86 || PPC64 || SUPERH || S390)
Dave Hansen3947be12005-10-29 18:16:54 -0700133
134comment "Memory hotplug is currently incompatible with Software Suspend"
Gerald Schaefer03997902009-06-16 10:30:48 +0200135 depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390
Dave Hansen3947be12005-10-29 18:16:54 -0700136
Keith Manntheyec69acb2006-09-30 23:27:05 -0700137config MEMORY_HOTPLUG_SPARSE
138 def_bool y
139 depends on SPARSEMEM && MEMORY_HOTPLUG
140
KAMEZAWA Hiroyuki0c0e6192007-10-16 01:26:12 -0700141config MEMORY_HOTREMOVE
142 bool "Allow for memory hot remove"
143 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
144 depends on MIGRATION
145
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700146#
147# If we have space for more page flags then we can enable additional
148# optimizations and functionality.
149#
150# Regular Sparsemem takes page flag bits for the sectionid if it does not
151# use a virtual memmap. Disable extended page flags for 32 bit platforms
152# that require the use of a sectionid in the page flags.
153#
154config PAGEFLAGS_EXTENDED
155 def_bool y
H. Peter Anvina269cca2009-08-31 11:17:44 -0700156 depends on 64BIT || SPARSEMEM_VMEMMAP || !SPARSEMEM
Christoph Lametere20b8cc2008-04-28 02:12:55 -0700157
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700158# Heavily threaded applications may benefit from splitting the mm-wide
159# page_table_lock, so that faults on different parts of the user address
160# space can be handled with less contention: split it at this NR_CPUS.
161# Default to 4 for wider testing, though 8 might be more appropriate.
162# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800163# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700164#
165config SPLIT_PTLOCK_CPUS
166 int
167 default "4096" if ARM && !CPU_CACHE_VIPT
Hugh Dickins7b6ac9d2005-11-23 13:37:37 -0800168 default "4096" if PARISC && !PA20
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700169 default "4"
Christoph Lameter7cbe34c2006-01-08 01:00:49 -0800170
171#
172# support for page migration
173#
174config MIGRATION
Christoph Lameterb20a3502006-03-22 00:09:12 -0800175 bool "Page migration"
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700176 def_bool y
Gerald Schaefer83d16742008-07-23 21:28:22 -0700177 depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
Christoph Lameterb20a3502006-03-22 00:09:12 -0800178 help
179 Allows the migration of the physical location of pages of processes
180 while the virtual addresses are not changed. This is useful for
181 example on NUMA systems to put pages nearer to the processors accessing
182 the page.
Greg Kroah-Hartman6550e072006-06-12 17:11:31 -0700183
Jeremy Fitzhardinge600715d2008-09-11 01:31:45 -0700184config PHYS_ADDR_T_64BIT
185 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
186
Christoph Lameter4b51d662007-02-10 01:43:10 -0800187config ZONE_DMA_FLAG
188 int
189 default "0" if !ZONE_DMA
190 default "1"
191
Christoph Lameter2a7326b2007-07-17 04:03:37 -0700192config BOUNCE
193 def_bool y
194 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
195
Christoph Lameter6225e932007-05-06 14:49:50 -0700196config NR_QUICK
197 int
198 depends on QUICKLIST
Haavard Skinnemoen38510752008-01-14 23:35:32 +0100199 default "2" if SUPERH || AVR32
Christoph Lameter6225e932007-05-06 14:49:50 -0700200 default "1"
Stephen Rothwellf057eac2007-07-15 23:40:05 -0700201
202config VIRT_TO_BUS
203 def_bool y
204 depends on !ARCH_NO_VIRT_TO_BUS
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700205
David Howells33925b22009-03-31 15:23:26 -0700206config HAVE_MLOCK
207 bool
208 default y if MMU=y
209
210config HAVE_MLOCKED_PAGE_BIT
211 bool
KOSAKI Motohiro68377652009-06-16 15:32:51 -0700212 default y if HAVE_MLOCK=y
David Howells33925b22009-03-31 15:23:26 -0700213
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700214config MMU_NOTIFIER
215 bool
David Howellsfc4d5c22009-05-06 16:03:05 -0700216
Hugh Dickinsf8af4da2009-09-21 17:01:57 -0700217config KSM
218 bool "Enable KSM for page merging"
219 depends on MMU
220 help
221 Enable Kernel Samepage Merging: KSM periodically scans those areas
222 of an application's address space that an app has advised may be
223 mergeable. When it finds pages of identical content, it replaces
224 the many instances by a single resident page with that content, so
225 saving memory until one or another app needs to modify the content.
226 Recommended for use with KVM, or with other duplicative applications.
227
Christoph Lametere0a94c22009-06-03 16:04:31 -0400228config DEFAULT_MMAP_MIN_ADDR
229 int "Low address space to protect from user allocation"
230 default 4096
231 help
232 This is the portion of low virtual memory which should be protected
233 from userspace allocation. Keeping a user from writing to low pages
234 can help reduce the impact of kernel NULL pointer bugs.
235
236 For most ia64, ppc64 and x86 users with lots of address space
237 a value of 65536 is reasonable and should cause no problems.
238 On arm and other archs it should not be higher than 32768.
Eric Paris788084a2009-07-31 12:54:11 -0400239 Programs which use vm86 functionality or have some need to map
240 this low address space will need CAP_SYS_RAWIO or disable this
241 protection by setting the value to 0.
Christoph Lametere0a94c22009-06-03 16:04:31 -0400242
243 This value can be changed after boot using the
244 /proc/sys/vm/mmap_min_addr tunable.
245
246
David Howellsfc4d5c22009-05-06 16:03:05 -0700247config NOMMU_INITIAL_TRIM_EXCESS
248 int "Turn on mmap() excess space trimming before booting"
249 depends on !MMU
250 default 1
251 help
252 The NOMMU mmap() frequently needs to allocate large contiguous chunks
253 of memory on which to store mappings, but it can only ask the system
254 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
255 more than it requires. To deal with this, mmap() is able to trim off
256 the excess and return it to the allocator.
257
258 If trimming is enabled, the excess is trimmed off and returned to the
259 system allocator, which can cause extra fragmentation, particularly
260 if there are a lot of transient processes.
261
262 If trimming is disabled, the excess is kept, but not used, which for
263 long-term mappings means that the space is wasted.
264
265 Trimming can be dynamically controlled through a sysctl option
266 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
267 excess pages there must be before trimming should occur, or zero if
268 no trimming is to occur.
269
270 This option specifies the initial value of this option. The default
271 of 1 says that all excess pages should be trimmed.
272
273 See Documentation/nommu-mmap.txt for more information.