1e1785e85SDave Hansenconfig SELECT_MEMORY_MODEL 2e1785e85SDave Hansen def_bool y 3e1785e85SDave Hansen depends on EXPERIMENTAL || ARCH_SELECT_MEMORY_MODEL 4e1785e85SDave Hansen 53a9da765SDave Hansenchoice 63a9da765SDave Hansen prompt "Memory model" 7e1785e85SDave Hansen depends on SELECT_MEMORY_MODEL 8e1785e85SDave Hansen default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT 9d41dee36SAndy Whitcroft default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 10e1785e85SDave Hansen default FLATMEM_MANUAL 113a9da765SDave Hansen 12e1785e85SDave Hansenconfig FLATMEM_MANUAL 133a9da765SDave Hansen bool "Flat Memory" 14c898ec16SAnton Blanchard depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE 153a9da765SDave Hansen help 163a9da765SDave Hansen This option allows you to change some of the ways that 173a9da765SDave Hansen Linux manages its memory internally. Most users will 183a9da765SDave Hansen only have one option here: FLATMEM. This is normal 193a9da765SDave Hansen and a correct option. 203a9da765SDave Hansen 21d41dee36SAndy Whitcroft Some users of more advanced features like NUMA and 22d41dee36SAndy Whitcroft memory hotplug may have different options here. 23d41dee36SAndy Whitcroft DISCONTIGMEM is an more mature, better tested system, 24d41dee36SAndy Whitcroft but is incompatible with memory hotplug and may suffer 25d41dee36SAndy Whitcroft decreased performance over SPARSEMEM. If unsure between 26d41dee36SAndy Whitcroft "Sparse Memory" and "Discontiguous Memory", choose 27d41dee36SAndy Whitcroft "Discontiguous Memory". 28d41dee36SAndy Whitcroft 29d41dee36SAndy Whitcroft If unsure, choose this option (Flat Memory) over any other. 303a9da765SDave Hansen 31e1785e85SDave Hansenconfig DISCONTIGMEM_MANUAL 32f3519f91SDave Hansen bool "Discontiguous Memory" 333a9da765SDave Hansen depends on ARCH_DISCONTIGMEM_ENABLE 343a9da765SDave Hansen help 35785dcd44SDave Hansen This option provides enhanced support for discontiguous 36785dcd44SDave Hansen memory systems, over FLATMEM. These systems have holes 37785dcd44SDave Hansen in their physical address spaces, and this option provides 38785dcd44SDave Hansen more efficient handling of these holes. However, the vast 39785dcd44SDave Hansen majority of hardware has quite flat address spaces, and 40ad3d0a38SPhilipp Marek can have degraded performance from the extra overhead that 41785dcd44SDave Hansen this option imposes. 42785dcd44SDave Hansen 43785dcd44SDave Hansen Many NUMA configurations will have this as the only option. 44785dcd44SDave Hansen 453a9da765SDave Hansen If unsure, choose "Flat Memory" over this option. 463a9da765SDave Hansen 47d41dee36SAndy Whitcroftconfig SPARSEMEM_MANUAL 48d41dee36SAndy Whitcroft bool "Sparse Memory" 49d41dee36SAndy Whitcroft depends on ARCH_SPARSEMEM_ENABLE 50d41dee36SAndy Whitcroft help 51d41dee36SAndy Whitcroft This will be the only option for some systems, including 52d41dee36SAndy Whitcroft memory hotplug systems. This is normal. 53d41dee36SAndy Whitcroft 54d41dee36SAndy Whitcroft For many other systems, this will be an alternative to 55f3519f91SDave Hansen "Discontiguous Memory". This option provides some potential 56d41dee36SAndy Whitcroft performance benefits, along with decreased code complexity, 57d41dee36SAndy Whitcroft but it is newer, and more experimental. 58d41dee36SAndy Whitcroft 59d41dee36SAndy Whitcroft If unsure, choose "Discontiguous Memory" or "Flat Memory" 60d41dee36SAndy Whitcroft over this option. 61d41dee36SAndy Whitcroft 623a9da765SDave Hansenendchoice 633a9da765SDave Hansen 64e1785e85SDave Hansenconfig DISCONTIGMEM 65e1785e85SDave Hansen def_bool y 66e1785e85SDave Hansen depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL 67e1785e85SDave Hansen 68d41dee36SAndy Whitcroftconfig SPARSEMEM 69d41dee36SAndy Whitcroft def_bool y 70d41dee36SAndy Whitcroft depends on SPARSEMEM_MANUAL 71d41dee36SAndy Whitcroft 72e1785e85SDave Hansenconfig FLATMEM 73e1785e85SDave Hansen def_bool y 74d41dee36SAndy Whitcroft depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL 75d41dee36SAndy Whitcroft 76d41dee36SAndy Whitcroftconfig FLAT_NODE_MEM_MAP 77d41dee36SAndy Whitcroft def_bool y 78d41dee36SAndy Whitcroft depends on !SPARSEMEM 79e1785e85SDave Hansen 8093b7504eSDave Hansen# 8193b7504eSDave Hansen# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's 8293b7504eSDave Hansen# to represent different areas of memory. This variable allows 8393b7504eSDave Hansen# those dependencies to exist individually. 8493b7504eSDave Hansen# 8593b7504eSDave Hansenconfig NEED_MULTIPLE_NODES 8693b7504eSDave Hansen def_bool y 8793b7504eSDave Hansen depends on DISCONTIGMEM || NUMA 88af705362SAndy Whitcroft 89af705362SAndy Whitcroftconfig HAVE_MEMORY_PRESENT 90af705362SAndy Whitcroft def_bool y 91d41dee36SAndy Whitcroft depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM 92802f192eSBob Picco 93802f192eSBob Picco# 943e347261SBob Picco# SPARSEMEM_EXTREME (which is the default) does some bootmem 953e347261SBob Picco# allocations when memory_present() is called. If this cannot 963e347261SBob Picco# be done on your architecture, select this option. However, 973e347261SBob Picco# statically allocating the mem_section[] array can potentially 983e347261SBob Picco# consume vast quantities of .bss, so be careful. 993e347261SBob Picco# 1003e347261SBob Picco# This option will also potentially produce smaller runtime code 1013e347261SBob Picco# with gcc 3.4 and later. 1023e347261SBob Picco# 1033e347261SBob Piccoconfig SPARSEMEM_STATIC 1049ba16087SJan Beulich bool 1053e347261SBob Picco 1063e347261SBob Picco# 10744c09201SMatt LaPlante# Architecture platforms which require a two level mem_section in SPARSEMEM 108802f192eSBob Picco# must select this option. This is usually for architecture platforms with 109802f192eSBob Picco# an extremely sparse physical address space. 110802f192eSBob Picco# 1113e347261SBob Piccoconfig SPARSEMEM_EXTREME 1123e347261SBob Picco def_bool y 1133e347261SBob Picco depends on SPARSEMEM && !SPARSEMEM_STATIC 1144c21e2f2SHugh Dickins 11529c71111SAndy Whitcroftconfig SPARSEMEM_VMEMMAP_ENABLE 1169ba16087SJan Beulich bool 11729c71111SAndy Whitcroft 11829c71111SAndy Whitcroftconfig SPARSEMEM_VMEMMAP 119a5ee6daaSGeoff Levand bool "Sparse Memory virtual memmap" 120a5ee6daaSGeoff Levand depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 121a5ee6daaSGeoff Levand default y 122a5ee6daaSGeoff Levand help 123a5ee6daaSGeoff Levand SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 124a5ee6daaSGeoff Levand pfn_to_page and page_to_pfn operations. This is the most 125a5ee6daaSGeoff Levand efficient option when sufficient kernel resources are available. 12629c71111SAndy Whitcroft 1273947be19SDave Hansen# eventually, we can have this option just 'select SPARSEMEM' 1283947be19SDave Hansenconfig MEMORY_HOTPLUG 1293947be19SDave Hansen bool "Allow for memory hot-add" 130ec69acbbSKeith Mannthey depends on SPARSEMEM || X86_64_ACPI_NUMA 13103997904SGerald Schaefer depends on HOTPLUG && !(HIBERNATION && !S390) && ARCH_ENABLE_MEMORY_HOTPLUG 132421c175cSHeiko Carstens depends on (IA64 || X86 || PPC64 || SUPERH || S390) 1333947be19SDave Hansen 1343947be19SDave Hansencomment "Memory hotplug is currently incompatible with Software Suspend" 13503997904SGerald Schaefer depends on SPARSEMEM && HOTPLUG && HIBERNATION && !S390 1363947be19SDave Hansen 137ec69acbbSKeith Manntheyconfig MEMORY_HOTPLUG_SPARSE 138ec69acbbSKeith Mannthey def_bool y 139ec69acbbSKeith Mannthey depends on SPARSEMEM && MEMORY_HOTPLUG 140ec69acbbSKeith Mannthey 1410c0e6195SKAMEZAWA Hiroyukiconfig MEMORY_HOTREMOVE 1420c0e6195SKAMEZAWA Hiroyuki bool "Allow for memory hot remove" 1430c0e6195SKAMEZAWA Hiroyuki depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 1440c0e6195SKAMEZAWA Hiroyuki depends on MIGRATION 1450c0e6195SKAMEZAWA Hiroyuki 146e20b8ccaSChristoph Lameter# 147e20b8ccaSChristoph Lameter# If we have space for more page flags then we can enable additional 148e20b8ccaSChristoph Lameter# optimizations and functionality. 149e20b8ccaSChristoph Lameter# 150e20b8ccaSChristoph Lameter# Regular Sparsemem takes page flag bits for the sectionid if it does not 151e20b8ccaSChristoph Lameter# use a virtual memmap. Disable extended page flags for 32 bit platforms 152e20b8ccaSChristoph Lameter# that require the use of a sectionid in the page flags. 153e20b8ccaSChristoph Lameter# 154e20b8ccaSChristoph Lameterconfig PAGEFLAGS_EXTENDED 155e20b8ccaSChristoph Lameter def_bool y 156e20b8ccaSChristoph Lameter depends on 64BIT || SPARSEMEM_VMEMMAP || !NUMA || !SPARSEMEM 157e20b8ccaSChristoph Lameter 1584c21e2f2SHugh Dickins# Heavily threaded applications may benefit from splitting the mm-wide 1594c21e2f2SHugh Dickins# page_table_lock, so that faults on different parts of the user address 1604c21e2f2SHugh Dickins# space can be handled with less contention: split it at this NR_CPUS. 1614c21e2f2SHugh Dickins# Default to 4 for wider testing, though 8 might be more appropriate. 1624c21e2f2SHugh Dickins# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 1637b6ac9dfSHugh Dickins# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 1644c21e2f2SHugh Dickins# 1654c21e2f2SHugh Dickinsconfig SPLIT_PTLOCK_CPUS 1664c21e2f2SHugh Dickins int 1674c21e2f2SHugh Dickins default "4096" if ARM && !CPU_CACHE_VIPT 1687b6ac9dfSHugh Dickins default "4096" if PARISC && !PA20 1694c21e2f2SHugh Dickins default "4" 1707cbe34cfSChristoph Lameter 1717cbe34cfSChristoph Lameter# 1727cbe34cfSChristoph Lameter# support for page migration 1737cbe34cfSChristoph Lameter# 1747cbe34cfSChristoph Lameterconfig MIGRATION 175b20a3503SChristoph Lameter bool "Page migration" 1766c5240aeSChristoph Lameter def_bool y 17783d1674aSGerald Schaefer depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE 178b20a3503SChristoph Lameter help 179b20a3503SChristoph Lameter Allows the migration of the physical location of pages of processes 180b20a3503SChristoph Lameter while the virtual addresses are not changed. This is useful for 181b20a3503SChristoph Lameter example on NUMA systems to put pages nearer to the processors accessing 182b20a3503SChristoph Lameter the page. 1836550e07fSGreg Kroah-Hartman 184600715dcSJeremy Fitzhardingeconfig PHYS_ADDR_T_64BIT 185600715dcSJeremy Fitzhardinge def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT 186600715dcSJeremy Fitzhardinge 1874b51d669SChristoph Lameterconfig ZONE_DMA_FLAG 1884b51d669SChristoph Lameter int 1894b51d669SChristoph Lameter default "0" if !ZONE_DMA 1904b51d669SChristoph Lameter default "1" 1914b51d669SChristoph Lameter 1922a7326b5SChristoph Lameterconfig BOUNCE 1932a7326b5SChristoph Lameter def_bool y 1942a7326b5SChristoph Lameter depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) 1952a7326b5SChristoph Lameter 1966225e937SChristoph Lameterconfig NR_QUICK 1976225e937SChristoph Lameter int 1986225e937SChristoph Lameter depends on QUICKLIST 19938510754SHaavard Skinnemoen default "2" if SUPERH || AVR32 2006225e937SChristoph Lameter default "1" 201f057eac0SStephen Rothwell 202f057eac0SStephen Rothwellconfig VIRT_TO_BUS 203f057eac0SStephen Rothwell def_bool y 204f057eac0SStephen Rothwell depends on !ARCH_NO_VIRT_TO_BUS 205cddb8a5cSAndrea Arcangeli 20633925b25SDavid Howellsconfig HAVE_MLOCK 20733925b25SDavid Howells bool 20833925b25SDavid Howells default y if MMU=y 20933925b25SDavid Howells 21033925b25SDavid Howellsconfig HAVE_MLOCKED_PAGE_BIT 21133925b25SDavid Howells bool 21268377659SKOSAKI Motohiro default y if HAVE_MLOCK=y 21333925b25SDavid Howells 214cddb8a5cSAndrea Arcangeliconfig MMU_NOTIFIER 215cddb8a5cSAndrea Arcangeli bool 216fc4d5c29SDavid Howells 217e0a94c2aSChristoph Lameterconfig DEFAULT_MMAP_MIN_ADDR 218e0a94c2aSChristoph Lameter int "Low address space to protect from user allocation" 219e0a94c2aSChristoph Lameter default 4096 220e0a94c2aSChristoph Lameter help 221e0a94c2aSChristoph Lameter This is the portion of low virtual memory which should be protected 222e0a94c2aSChristoph Lameter from userspace allocation. Keeping a user from writing to low pages 223e0a94c2aSChristoph Lameter can help reduce the impact of kernel NULL pointer bugs. 224e0a94c2aSChristoph Lameter 225e0a94c2aSChristoph Lameter For most ia64, ppc64 and x86 users with lots of address space 226e0a94c2aSChristoph Lameter a value of 65536 is reasonable and should cause no problems. 227e0a94c2aSChristoph Lameter On arm and other archs it should not be higher than 32768. 228*788084abSEric Paris Programs which use vm86 functionality or have some need to map 229*788084abSEric Paris this low address space will need CAP_SYS_RAWIO or disable this 230*788084abSEric Paris protection by setting the value to 0. 231e0a94c2aSChristoph Lameter 232e0a94c2aSChristoph Lameter This value can be changed after boot using the 233e0a94c2aSChristoph Lameter /proc/sys/vm/mmap_min_addr tunable. 234e0a94c2aSChristoph Lameter 235e0a94c2aSChristoph Lameter 236fc4d5c29SDavid Howellsconfig NOMMU_INITIAL_TRIM_EXCESS 237fc4d5c29SDavid Howells int "Turn on mmap() excess space trimming before booting" 238fc4d5c29SDavid Howells depends on !MMU 239fc4d5c29SDavid Howells default 1 240fc4d5c29SDavid Howells help 241fc4d5c29SDavid Howells The NOMMU mmap() frequently needs to allocate large contiguous chunks 242fc4d5c29SDavid Howells of memory on which to store mappings, but it can only ask the system 243fc4d5c29SDavid Howells allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 244fc4d5c29SDavid Howells more than it requires. To deal with this, mmap() is able to trim off 245fc4d5c29SDavid Howells the excess and return it to the allocator. 246fc4d5c29SDavid Howells 247fc4d5c29SDavid Howells If trimming is enabled, the excess is trimmed off and returned to the 248fc4d5c29SDavid Howells system allocator, which can cause extra fragmentation, particularly 249fc4d5c29SDavid Howells if there are a lot of transient processes. 250fc4d5c29SDavid Howells 251fc4d5c29SDavid Howells If trimming is disabled, the excess is kept, but not used, which for 252fc4d5c29SDavid Howells long-term mappings means that the space is wasted. 253fc4d5c29SDavid Howells 254fc4d5c29SDavid Howells Trimming can be dynamically controlled through a sysctl option 255fc4d5c29SDavid Howells (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 256fc4d5c29SDavid Howells excess pages there must be before trimming should occur, or zero if 257fc4d5c29SDavid Howells no trimming is to occur. 258fc4d5c29SDavid Howells 259fc4d5c29SDavid Howells This option specifies the initial value of this option. The default 260fc4d5c29SDavid Howells of 1 says that all excess pages should be trimmed. 261fc4d5c29SDavid Howells 262fc4d5c29SDavid Howells See Documentation/nommu-mmap.txt for more information. 263