1config SELECT_MEMORY_MODEL 2 def_bool y 3 depends on 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 a 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 bool 133 134config HAVE_MEMBLOCK_NODE_MAP 135 bool 136 137config HAVE_MEMBLOCK_PHYS_MAP 138 bool 139 140config HAVE_GENERIC_GUP 141 bool 142 143config ARCH_DISCARD_MEMBLOCK 144 bool 145 146config NO_BOOTMEM 147 bool 148 149config MEMORY_ISOLATION 150 bool 151 152# 153# Only be set on architectures that have completely implemented memory hotplug 154# feature. If you are not sure, don't touch it. 155# 156config HAVE_BOOTMEM_INFO_NODE 157 def_bool n 158 159# eventually, we can have this option just 'select SPARSEMEM' 160config MEMORY_HOTPLUG 161 bool "Allow for memory hot-add" 162 depends on SPARSEMEM || X86_64_ACPI_NUMA 163 depends on ARCH_ENABLE_MEMORY_HOTPLUG 164 165config MEMORY_HOTPLUG_SPARSE 166 def_bool y 167 depends on SPARSEMEM && MEMORY_HOTPLUG 168 169config MEMORY_HOTPLUG_DEFAULT_ONLINE 170 bool "Online the newly added memory blocks by default" 171 default n 172 depends on MEMORY_HOTPLUG 173 help 174 This option sets the default policy setting for memory hotplug 175 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 176 determines what happens to newly added memory regions. Policy setting 177 can always be changed at runtime. 178 See Documentation/memory-hotplug.txt for more information. 179 180 Say Y here if you want all hot-plugged memory blocks to appear in 181 'online' state by default. 182 Say N here if you want the default policy to keep all hot-plugged 183 memory blocks in 'offline' state. 184 185config MEMORY_HOTREMOVE 186 bool "Allow for memory hot remove" 187 select MEMORY_ISOLATION 188 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 189 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 190 depends on MIGRATION 191 192# Heavily threaded applications may benefit from splitting the mm-wide 193# page_table_lock, so that faults on different parts of the user address 194# space can be handled with less contention: split it at this NR_CPUS. 195# Default to 4 for wider testing, though 8 might be more appropriate. 196# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 197# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 198# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 199# 200config SPLIT_PTLOCK_CPUS 201 int 202 default "999999" if !MMU 203 default "999999" if ARM && !CPU_CACHE_VIPT 204 default "999999" if PARISC && !PA20 205 default "4" 206 207config ARCH_ENABLE_SPLIT_PMD_PTLOCK 208 bool 209 210# 211# support for memory balloon 212config MEMORY_BALLOON 213 bool 214 215# 216# support for memory balloon compaction 217config BALLOON_COMPACTION 218 bool "Allow for balloon memory compaction/migration" 219 def_bool y 220 depends on COMPACTION && MEMORY_BALLOON 221 help 222 Memory fragmentation introduced by ballooning might reduce 223 significantly the number of 2MB contiguous memory blocks that can be 224 used within a guest, thus imposing performance penalties associated 225 with the reduced number of transparent huge pages that could be used 226 by the guest workload. Allowing the compaction & migration for memory 227 pages enlisted as being part of memory balloon devices avoids the 228 scenario aforementioned and helps improving memory defragmentation. 229 230# 231# support for memory compaction 232config COMPACTION 233 bool "Allow for memory compaction" 234 def_bool y 235 select MIGRATION 236 depends on MMU 237 help 238 Compaction is the only memory management component to form 239 high order (larger physically contiguous) memory blocks 240 reliably. The page allocator relies on compaction heavily and 241 the lack of the feature can lead to unexpected OOM killer 242 invocations for high order memory requests. You shouldn't 243 disable this option unless there really is a strong reason for 244 it and then we would be really interested to hear about that at 245 linux-mm@kvack.org. 246 247# 248# support for page migration 249# 250config MIGRATION 251 bool "Page migration" 252 def_bool y 253 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 254 help 255 Allows the migration of the physical location of pages of processes 256 while the virtual addresses are not changed. This is useful in 257 two situations. The first is on NUMA systems to put pages nearer 258 to the processors accessing. The second is when allocating huge 259 pages as migration can relocate pages to satisfy a huge page 260 allocation instead of reclaiming. 261 262config ARCH_ENABLE_HUGEPAGE_MIGRATION 263 bool 264 265config PHYS_ADDR_T_64BIT 266 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT 267 268config BOUNCE 269 bool "Enable bounce buffers" 270 default y 271 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) 272 help 273 Enable bounce buffers for devices that cannot access 274 the full range of memory available to the CPU. Enabled 275 by default when ZONE_DMA or HIGHMEM is selected, but you 276 may say n to override this. 277 278# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often 279# have more than 4GB of memory, but we don't currently use the IOTLB to present 280# a 32-bit address to OHCI. So we need to use a bounce pool instead. 281config NEED_BOUNCE_POOL 282 bool 283 default y if TILE && USB_OHCI_HCD 284 285config NR_QUICK 286 int 287 depends on QUICKLIST 288 default "1" 289 290config VIRT_TO_BUS 291 bool 292 help 293 An architecture should select this if it implements the 294 deprecated interface virt_to_bus(). All new architectures 295 should probably not select this. 296 297 298config MMU_NOTIFIER 299 bool 300 select SRCU 301 302config KSM 303 bool "Enable KSM for page merging" 304 depends on MMU 305 help 306 Enable Kernel Samepage Merging: KSM periodically scans those areas 307 of an application's address space that an app has advised may be 308 mergeable. When it finds pages of identical content, it replaces 309 the many instances by a single page with that content, so 310 saving memory until one or another app needs to modify the content. 311 Recommended for use with KVM, or with other duplicative applications. 312 See Documentation/vm/ksm.txt for more information: KSM is inactive 313 until a program has madvised that an area is MADV_MERGEABLE, and 314 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 315 316config DEFAULT_MMAP_MIN_ADDR 317 int "Low address space to protect from user allocation" 318 depends on MMU 319 default 4096 320 help 321 This is the portion of low virtual memory which should be protected 322 from userspace allocation. Keeping a user from writing to low pages 323 can help reduce the impact of kernel NULL pointer bugs. 324 325 For most ia64, ppc64 and x86 users with lots of address space 326 a value of 65536 is reasonable and should cause no problems. 327 On arm and other archs it should not be higher than 32768. 328 Programs which use vm86 functionality or have some need to map 329 this low address space will need CAP_SYS_RAWIO or disable this 330 protection by setting the value to 0. 331 332 This value can be changed after boot using the 333 /proc/sys/vm/mmap_min_addr tunable. 334 335config ARCH_SUPPORTS_MEMORY_FAILURE 336 bool 337 338config MEMORY_FAILURE 339 depends on MMU 340 depends on ARCH_SUPPORTS_MEMORY_FAILURE 341 bool "Enable recovery from hardware memory errors" 342 select MEMORY_ISOLATION 343 select RAS 344 help 345 Enables code to recover from some memory failures on systems 346 with MCA recovery. This allows a system to continue running 347 even when some of its memory has uncorrected errors. This requires 348 special hardware support and typically ECC memory. 349 350config HWPOISON_INJECT 351 tristate "HWPoison pages injector" 352 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 353 select PROC_PAGE_MONITOR 354 355config NOMMU_INITIAL_TRIM_EXCESS 356 int "Turn on mmap() excess space trimming before booting" 357 depends on !MMU 358 default 1 359 help 360 The NOMMU mmap() frequently needs to allocate large contiguous chunks 361 of memory on which to store mappings, but it can only ask the system 362 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 363 more than it requires. To deal with this, mmap() is able to trim off 364 the excess and return it to the allocator. 365 366 If trimming is enabled, the excess is trimmed off and returned to the 367 system allocator, which can cause extra fragmentation, particularly 368 if there are a lot of transient processes. 369 370 If trimming is disabled, the excess is kept, but not used, which for 371 long-term mappings means that the space is wasted. 372 373 Trimming can be dynamically controlled through a sysctl option 374 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 375 excess pages there must be before trimming should occur, or zero if 376 no trimming is to occur. 377 378 This option specifies the initial value of this option. The default 379 of 1 says that all excess pages should be trimmed. 380 381 See Documentation/nommu-mmap.txt for more information. 382 383config TRANSPARENT_HUGEPAGE 384 bool "Transparent Hugepage Support" 385 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE 386 select COMPACTION 387 select RADIX_TREE_MULTIORDER 388 help 389 Transparent Hugepages allows the kernel to use huge pages and 390 huge tlb transparently to the applications whenever possible. 391 This feature can improve computing performance to certain 392 applications by speeding up page faults during memory 393 allocation, by reducing the number of tlb misses and by speeding 394 up the pagetable walking. 395 396 If memory constrained on embedded, you may want to say N. 397 398choice 399 prompt "Transparent Hugepage Support sysfs defaults" 400 depends on TRANSPARENT_HUGEPAGE 401 default TRANSPARENT_HUGEPAGE_ALWAYS 402 help 403 Selects the sysfs defaults for Transparent Hugepage Support. 404 405 config TRANSPARENT_HUGEPAGE_ALWAYS 406 bool "always" 407 help 408 Enabling Transparent Hugepage always, can increase the 409 memory footprint of applications without a guaranteed 410 benefit but it will work automatically for all applications. 411 412 config TRANSPARENT_HUGEPAGE_MADVISE 413 bool "madvise" 414 help 415 Enabling Transparent Hugepage madvise, will only provide a 416 performance improvement benefit to the applications using 417 madvise(MADV_HUGEPAGE) but it won't risk to increase the 418 memory footprint of applications without a guaranteed 419 benefit. 420endchoice 421 422config ARCH_WANTS_THP_SWAP 423 def_bool n 424 425config THP_SWAP 426 def_bool y 427 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP 428 help 429 Swap transparent huge pages in one piece, without splitting. 430 XXX: For now this only does clustered swap space allocation. 431 432 For selection by architectures with reasonable THP sizes. 433 434config TRANSPARENT_HUGE_PAGECACHE 435 def_bool y 436 depends on TRANSPARENT_HUGEPAGE 437 438# 439# UP and nommu archs use km based percpu allocator 440# 441config NEED_PER_CPU_KM 442 depends on !SMP 443 bool 444 default y 445 446config CLEANCACHE 447 bool "Enable cleancache driver to cache clean pages if tmem is present" 448 default n 449 help 450 Cleancache can be thought of as a page-granularity victim cache 451 for clean pages that the kernel's pageframe replacement algorithm 452 (PFRA) would like to keep around, but can't since there isn't enough 453 memory. So when the PFRA "evicts" a page, it first attempts to use 454 cleancache code to put the data contained in that page into 455 "transcendent memory", memory that is not directly accessible or 456 addressable by the kernel and is of unknown and possibly 457 time-varying size. And when a cleancache-enabled 458 filesystem wishes to access a page in a file on disk, it first 459 checks cleancache to see if it already contains it; if it does, 460 the page is copied into the kernel and a disk access is avoided. 461 When a transcendent memory driver is available (such as zcache or 462 Xen transcendent memory), a significant I/O reduction 463 may be achieved. When none is available, all cleancache calls 464 are reduced to a single pointer-compare-against-NULL resulting 465 in a negligible performance hit. 466 467 If unsure, say Y to enable cleancache 468 469config FRONTSWAP 470 bool "Enable frontswap to cache swap pages if tmem is present" 471 depends on SWAP 472 default n 473 help 474 Frontswap is so named because it can be thought of as the opposite 475 of a "backing" store for a swap device. The data is stored into 476 "transcendent memory", memory that is not directly accessible or 477 addressable by the kernel and is of unknown and possibly 478 time-varying size. When space in transcendent memory is available, 479 a significant swap I/O reduction may be achieved. When none is 480 available, all frontswap calls are reduced to a single pointer- 481 compare-against-NULL resulting in a negligible performance hit 482 and swap data is stored as normal on the matching swap device. 483 484 If unsure, say Y to enable frontswap. 485 486config CMA 487 bool "Contiguous Memory Allocator" 488 depends on HAVE_MEMBLOCK && MMU 489 select MIGRATION 490 select MEMORY_ISOLATION 491 help 492 This enables the Contiguous Memory Allocator which allows other 493 subsystems to allocate big physically-contiguous blocks of memory. 494 CMA reserves a region of memory and allows only movable pages to 495 be allocated from it. This way, the kernel can use the memory for 496 pagecache and when a subsystem requests for contiguous area, the 497 allocated pages are migrated away to serve the contiguous request. 498 499 If unsure, say "n". 500 501config CMA_DEBUG 502 bool "CMA debug messages (DEVELOPMENT)" 503 depends on DEBUG_KERNEL && CMA 504 help 505 Turns on debug messages in CMA. This produces KERN_DEBUG 506 messages for every CMA call as well as various messages while 507 processing calls such as dma_alloc_from_contiguous(). 508 This option does not affect warning and error messages. 509 510config CMA_DEBUGFS 511 bool "CMA debugfs interface" 512 depends on CMA && DEBUG_FS 513 help 514 Turns on the DebugFS interface for CMA. 515 516config CMA_AREAS 517 int "Maximum count of the CMA areas" 518 depends on CMA 519 default 7 520 help 521 CMA allows to create CMA areas for particular purpose, mainly, 522 used as device private area. This parameter sets the maximum 523 number of CMA area in the system. 524 525 If unsure, leave the default value "7". 526 527config MEM_SOFT_DIRTY 528 bool "Track memory changes" 529 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 530 select PROC_PAGE_MONITOR 531 help 532 This option enables memory changes tracking by introducing a 533 soft-dirty bit on pte-s. This bit it set when someone writes 534 into a page just as regular dirty bit, but unlike the latter 535 it can be cleared by hands. 536 537 See Documentation/vm/soft-dirty.txt for more details. 538 539config ZSWAP 540 bool "Compressed cache for swap pages (EXPERIMENTAL)" 541 depends on FRONTSWAP && CRYPTO=y 542 select CRYPTO_LZO 543 select ZPOOL 544 default n 545 help 546 A lightweight compressed cache for swap pages. It takes 547 pages that are in the process of being swapped out and attempts to 548 compress them into a dynamically allocated RAM-based memory pool. 549 This can result in a significant I/O reduction on swap device and, 550 in the case where decompressing from RAM is faster that swap device 551 reads, can also improve workload performance. 552 553 This is marked experimental because it is a new feature (as of 554 v3.11) that interacts heavily with memory reclaim. While these 555 interactions don't cause any known issues on simple memory setups, 556 they have not be fully explored on the large set of potential 557 configurations and workloads that exist. 558 559config ZPOOL 560 tristate "Common API for compressed memory storage" 561 default n 562 help 563 Compressed memory storage API. This allows using either zbud or 564 zsmalloc. 565 566config ZBUD 567 tristate "Low (Up to 2x) density storage for compressed pages" 568 default n 569 help 570 A special purpose allocator for storing compressed pages. 571 It is designed to store up to two compressed pages per physical 572 page. While this design limits storage density, it has simple and 573 deterministic reclaim properties that make it preferable to a higher 574 density approach when reclaim will be used. 575 576config Z3FOLD 577 tristate "Up to 3x density storage for compressed pages" 578 depends on ZPOOL 579 default n 580 help 581 A special purpose allocator for storing compressed pages. 582 It is designed to store up to three compressed pages per physical 583 page. It is a ZBUD derivative so the simplicity and determinism are 584 still there. 585 586config ZSMALLOC 587 tristate "Memory allocator for compressed pages" 588 depends on MMU 589 default n 590 help 591 zsmalloc is a slab-based memory allocator designed to store 592 compressed RAM pages. zsmalloc uses virtual memory mapping 593 in order to reduce fragmentation. However, this results in a 594 non-standard allocator interface where a handle, not a pointer, is 595 returned by an alloc(). This handle must be mapped in order to 596 access the allocated space. 597 598config PGTABLE_MAPPING 599 bool "Use page table mapping to access object in zsmalloc" 600 depends on ZSMALLOC 601 help 602 By default, zsmalloc uses a copy-based object mapping method to 603 access allocations that span two pages. However, if a particular 604 architecture (ex, ARM) performs VM mapping faster than copying, 605 then you should select this. This causes zsmalloc to use page table 606 mapping rather than copying for object mapping. 607 608 You can check speed with zsmalloc benchmark: 609 https://github.com/spartacus06/zsmapbench 610 611config ZSMALLOC_STAT 612 bool "Export zsmalloc statistics" 613 depends on ZSMALLOC 614 select DEBUG_FS 615 help 616 This option enables code in the zsmalloc to collect various 617 statistics about whats happening in zsmalloc and exports that 618 information to userspace via debugfs. 619 If unsure, say N. 620 621config GENERIC_EARLY_IOREMAP 622 bool 623 624config MAX_STACK_SIZE_MB 625 int "Maximum user stack size for 32-bit processes (MB)" 626 default 80 627 range 8 256 if METAG 628 range 8 2048 629 depends on STACK_GROWSUP && (!64BIT || COMPAT) 630 help 631 This is the maximum stack size in Megabytes in the VM layout of 32-bit 632 user processes when the stack grows upwards (currently only on parisc 633 and metag arch). The stack will be located at the highest memory 634 address minus the given value, unless the RLIMIT_STACK hard limit is 635 changed to a smaller value in which case that is used. 636 637 A sane initial value is 80 MB. 638 639# For architectures that support deferred memory initialisation 640config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 641 bool 642 643config DEFERRED_STRUCT_PAGE_INIT 644 bool "Defer initialisation of struct pages to kthreads" 645 default n 646 depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 647 depends on NO_BOOTMEM && MEMORY_HOTPLUG 648 depends on !FLATMEM 649 help 650 Ordinarily all struct pages are initialised during early boot in a 651 single thread. On very large machines this can take a considerable 652 amount of time. If this option is set, large machines will bring up 653 a subset of memmap at boot and then initialise the rest in parallel 654 by starting one-off "pgdatinitX" kernel thread for each node X. This 655 has a potential performance impact on processes running early in the 656 lifetime of the system until these kthreads finish the 657 initialisation. 658 659config IDLE_PAGE_TRACKING 660 bool "Enable idle page tracking" 661 depends on SYSFS && MMU 662 select PAGE_EXTENSION if !64BIT 663 help 664 This feature allows to estimate the amount of user pages that have 665 not been touched during a given period of time. This information can 666 be useful to tune memory cgroup limits and/or for job placement 667 within a compute cluster. 668 669 See Documentation/vm/idle_page_tracking.txt for more details. 670 671# arch_add_memory() comprehends device memory 672config ARCH_HAS_ZONE_DEVICE 673 bool 674 675config ZONE_DEVICE 676 bool "Device memory (pmem, etc...) hotplug support" 677 depends on MEMORY_HOTPLUG 678 depends on MEMORY_HOTREMOVE 679 depends on SPARSEMEM_VMEMMAP 680 depends on ARCH_HAS_ZONE_DEVICE 681 682 help 683 Device memory hotplug support allows for establishing pmem, 684 or other device driver discovered memory regions, in the 685 memmap. This allows pfn_to_page() lookups of otherwise 686 "device-physical" addresses which is needed for using a DAX 687 mapping in an O_DIRECT operation, among other things. 688 689 If FS_DAX is enabled, then say Y. 690 691config FRAME_VECTOR 692 bool 693 694config ARCH_USES_HIGH_VMA_FLAGS 695 bool 696config ARCH_HAS_PKEYS 697 bool 698 699config PERCPU_STATS 700 bool "Collect percpu memory statistics" 701 default n 702 help 703 This feature collects and exposes statistics via debugfs. The 704 information includes global and per chunk statistics, which can 705 be used to help understand percpu memory usage. 706