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_RCU_GUP 141 bool 142 143config ARCH_DISCARD_MEMBLOCK 144 bool 145 146config NO_BOOTMEM 147 bool 148 149config MEMORY_ISOLATION 150 bool 151 152config MOVABLE_NODE 153 bool "Enable to assign a node which has only movable memory" 154 depends on HAVE_MEMBLOCK 155 depends on NO_BOOTMEM 156 depends on X86_64 157 depends on NUMA 158 default n 159 help 160 Allow a node to have only movable memory. Pages used by the kernel, 161 such as direct mapping pages cannot be migrated. So the corresponding 162 memory device cannot be hotplugged. This option allows the following 163 two things: 164 - When the system is booting, node full of hotpluggable memory can 165 be arranged to have only movable memory so that the whole node can 166 be hot-removed. (need movable_node boot option specified). 167 - After the system is up, the option allows users to online all the 168 memory of a node as movable memory so that the whole node can be 169 hot-removed. 170 171 Users who don't use the memory hotplug feature are fine with this 172 option on since they don't specify movable_node boot option or they 173 don't online memory as movable. 174 175 Say Y here if you want to hotplug a whole node. 176 Say N here if you want kernel to use memory on all nodes evenly. 177 178# 179# Only be set on architectures that have completely implemented memory hotplug 180# feature. If you are not sure, don't touch it. 181# 182config HAVE_BOOTMEM_INFO_NODE 183 def_bool n 184 185# eventually, we can have this option just 'select SPARSEMEM' 186config MEMORY_HOTPLUG 187 bool "Allow for memory hot-add" 188 depends on SPARSEMEM || X86_64_ACPI_NUMA 189 depends on ARCH_ENABLE_MEMORY_HOTPLUG 190 191config MEMORY_HOTPLUG_SPARSE 192 def_bool y 193 depends on SPARSEMEM && MEMORY_HOTPLUG 194 195config MEMORY_HOTPLUG_DEFAULT_ONLINE 196 bool "Online the newly added memory blocks by default" 197 default n 198 depends on MEMORY_HOTPLUG 199 help 200 This option sets the default policy setting for memory hotplug 201 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 202 determines what happens to newly added memory regions. Policy setting 203 can always be changed at runtime. 204 See Documentation/memory-hotplug.txt for more information. 205 206 Say Y here if you want all hot-plugged memory blocks to appear in 207 'online' state by default. 208 Say N here if you want the default policy to keep all hot-plugged 209 memory blocks in 'offline' state. 210 211config MEMORY_HOTREMOVE 212 bool "Allow for memory hot remove" 213 select MEMORY_ISOLATION 214 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 215 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 216 depends on MIGRATION 217 218# Heavily threaded applications may benefit from splitting the mm-wide 219# page_table_lock, so that faults on different parts of the user address 220# space can be handled with less contention: split it at this NR_CPUS. 221# Default to 4 for wider testing, though 8 might be more appropriate. 222# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 223# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 224# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 225# 226config SPLIT_PTLOCK_CPUS 227 int 228 default "999999" if !MMU 229 default "999999" if ARM && !CPU_CACHE_VIPT 230 default "999999" if PARISC && !PA20 231 default "4" 232 233config ARCH_ENABLE_SPLIT_PMD_PTLOCK 234 bool 235 236# 237# support for memory balloon 238config MEMORY_BALLOON 239 bool 240 241# 242# support for memory balloon compaction 243config BALLOON_COMPACTION 244 bool "Allow for balloon memory compaction/migration" 245 def_bool y 246 depends on COMPACTION && MEMORY_BALLOON 247 help 248 Memory fragmentation introduced by ballooning might reduce 249 significantly the number of 2MB contiguous memory blocks that can be 250 used within a guest, thus imposing performance penalties associated 251 with the reduced number of transparent huge pages that could be used 252 by the guest workload. Allowing the compaction & migration for memory 253 pages enlisted as being part of memory balloon devices avoids the 254 scenario aforementioned and helps improving memory defragmentation. 255 256# 257# support for memory compaction 258config COMPACTION 259 bool "Allow for memory compaction" 260 def_bool y 261 select MIGRATION 262 depends on MMU 263 help 264 Allows the compaction of memory for the allocation of huge pages. 265 266# 267# support for page migration 268# 269config MIGRATION 270 bool "Page migration" 271 def_bool y 272 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 273 help 274 Allows the migration of the physical location of pages of processes 275 while the virtual addresses are not changed. This is useful in 276 two situations. The first is on NUMA systems to put pages nearer 277 to the processors accessing. The second is when allocating huge 278 pages as migration can relocate pages to satisfy a huge page 279 allocation instead of reclaiming. 280 281config ARCH_ENABLE_HUGEPAGE_MIGRATION 282 bool 283 284config PHYS_ADDR_T_64BIT 285 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT 286 287config BOUNCE 288 bool "Enable bounce buffers" 289 default y 290 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) 291 help 292 Enable bounce buffers for devices that cannot access 293 the full range of memory available to the CPU. Enabled 294 by default when ZONE_DMA or HIGHMEM is selected, but you 295 may say n to override this. 296 297# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often 298# have more than 4GB of memory, but we don't currently use the IOTLB to present 299# a 32-bit address to OHCI. So we need to use a bounce pool instead. 300config NEED_BOUNCE_POOL 301 bool 302 default y if TILE && USB_OHCI_HCD 303 304config NR_QUICK 305 int 306 depends on QUICKLIST 307 default "2" if AVR32 308 default "1" 309 310config VIRT_TO_BUS 311 bool 312 help 313 An architecture should select this if it implements the 314 deprecated interface virt_to_bus(). All new architectures 315 should probably not select this. 316 317 318config MMU_NOTIFIER 319 bool 320 select SRCU 321 322config KSM 323 bool "Enable KSM for page merging" 324 depends on MMU 325 help 326 Enable Kernel Samepage Merging: KSM periodically scans those areas 327 of an application's address space that an app has advised may be 328 mergeable. When it finds pages of identical content, it replaces 329 the many instances by a single page with that content, so 330 saving memory until one or another app needs to modify the content. 331 Recommended for use with KVM, or with other duplicative applications. 332 See Documentation/vm/ksm.txt for more information: KSM is inactive 333 until a program has madvised that an area is MADV_MERGEABLE, and 334 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 335 336config DEFAULT_MMAP_MIN_ADDR 337 int "Low address space to protect from user allocation" 338 depends on MMU 339 default 4096 340 help 341 This is the portion of low virtual memory which should be protected 342 from userspace allocation. Keeping a user from writing to low pages 343 can help reduce the impact of kernel NULL pointer bugs. 344 345 For most ia64, ppc64 and x86 users with lots of address space 346 a value of 65536 is reasonable and should cause no problems. 347 On arm and other archs it should not be higher than 32768. 348 Programs which use vm86 functionality or have some need to map 349 this low address space will need CAP_SYS_RAWIO or disable this 350 protection by setting the value to 0. 351 352 This value can be changed after boot using the 353 /proc/sys/vm/mmap_min_addr tunable. 354 355config ARCH_SUPPORTS_MEMORY_FAILURE 356 bool 357 358config MEMORY_FAILURE 359 depends on MMU 360 depends on ARCH_SUPPORTS_MEMORY_FAILURE 361 bool "Enable recovery from hardware memory errors" 362 select MEMORY_ISOLATION 363 select RAS 364 help 365 Enables code to recover from some memory failures on systems 366 with MCA recovery. This allows a system to continue running 367 even when some of its memory has uncorrected errors. This requires 368 special hardware support and typically ECC memory. 369 370config HWPOISON_INJECT 371 tristate "HWPoison pages injector" 372 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 373 select PROC_PAGE_MONITOR 374 375config NOMMU_INITIAL_TRIM_EXCESS 376 int "Turn on mmap() excess space trimming before booting" 377 depends on !MMU 378 default 1 379 help 380 The NOMMU mmap() frequently needs to allocate large contiguous chunks 381 of memory on which to store mappings, but it can only ask the system 382 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 383 more than it requires. To deal with this, mmap() is able to trim off 384 the excess and return it to the allocator. 385 386 If trimming is enabled, the excess is trimmed off and returned to the 387 system allocator, which can cause extra fragmentation, particularly 388 if there are a lot of transient processes. 389 390 If trimming is disabled, the excess is kept, but not used, which for 391 long-term mappings means that the space is wasted. 392 393 Trimming can be dynamically controlled through a sysctl option 394 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 395 excess pages there must be before trimming should occur, or zero if 396 no trimming is to occur. 397 398 This option specifies the initial value of this option. The default 399 of 1 says that all excess pages should be trimmed. 400 401 See Documentation/nommu-mmap.txt for more information. 402 403config TRANSPARENT_HUGEPAGE 404 bool "Transparent Hugepage Support" 405 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE 406 select COMPACTION 407 select RADIX_TREE_MULTIORDER 408 help 409 Transparent Hugepages allows the kernel to use huge pages and 410 huge tlb transparently to the applications whenever possible. 411 This feature can improve computing performance to certain 412 applications by speeding up page faults during memory 413 allocation, by reducing the number of tlb misses and by speeding 414 up the pagetable walking. 415 416 If memory constrained on embedded, you may want to say N. 417 418choice 419 prompt "Transparent Hugepage Support sysfs defaults" 420 depends on TRANSPARENT_HUGEPAGE 421 default TRANSPARENT_HUGEPAGE_ALWAYS 422 help 423 Selects the sysfs defaults for Transparent Hugepage Support. 424 425 config TRANSPARENT_HUGEPAGE_ALWAYS 426 bool "always" 427 help 428 Enabling Transparent Hugepage always, can increase the 429 memory footprint of applications without a guaranteed 430 benefit but it will work automatically for all applications. 431 432 config TRANSPARENT_HUGEPAGE_MADVISE 433 bool "madvise" 434 help 435 Enabling Transparent Hugepage madvise, will only provide a 436 performance improvement benefit to the applications using 437 madvise(MADV_HUGEPAGE) but it won't risk to increase the 438 memory footprint of applications without a guaranteed 439 benefit. 440endchoice 441 442# 443# UP and nommu archs use km based percpu allocator 444# 445config NEED_PER_CPU_KM 446 depends on !SMP 447 bool 448 default y 449 450config CLEANCACHE 451 bool "Enable cleancache driver to cache clean pages if tmem is present" 452 default n 453 help 454 Cleancache can be thought of as a page-granularity victim cache 455 for clean pages that the kernel's pageframe replacement algorithm 456 (PFRA) would like to keep around, but can't since there isn't enough 457 memory. So when the PFRA "evicts" a page, it first attempts to use 458 cleancache code to put the data contained in that page into 459 "transcendent memory", memory that is not directly accessible or 460 addressable by the kernel and is of unknown and possibly 461 time-varying size. And when a cleancache-enabled 462 filesystem wishes to access a page in a file on disk, it first 463 checks cleancache to see if it already contains it; if it does, 464 the page is copied into the kernel and a disk access is avoided. 465 When a transcendent memory driver is available (such as zcache or 466 Xen transcendent memory), a significant I/O reduction 467 may be achieved. When none is available, all cleancache calls 468 are reduced to a single pointer-compare-against-NULL resulting 469 in a negligible performance hit. 470 471 If unsure, say Y to enable cleancache 472 473config FRONTSWAP 474 bool "Enable frontswap to cache swap pages if tmem is present" 475 depends on SWAP 476 default n 477 help 478 Frontswap is so named because it can be thought of as the opposite 479 of a "backing" store for a swap device. The data is stored into 480 "transcendent memory", memory that is not directly accessible or 481 addressable by the kernel and is of unknown and possibly 482 time-varying size. When space in transcendent memory is available, 483 a significant swap I/O reduction may be achieved. When none is 484 available, all frontswap calls are reduced to a single pointer- 485 compare-against-NULL resulting in a negligible performance hit 486 and swap data is stored as normal on the matching swap device. 487 488 If unsure, say Y to enable frontswap. 489 490config CMA 491 bool "Contiguous Memory Allocator" 492 depends on HAVE_MEMBLOCK && MMU 493 select MIGRATION 494 select MEMORY_ISOLATION 495 help 496 This enables the Contiguous Memory Allocator which allows other 497 subsystems to allocate big physically-contiguous blocks of memory. 498 CMA reserves a region of memory and allows only movable pages to 499 be allocated from it. This way, the kernel can use the memory for 500 pagecache and when a subsystem requests for contiguous area, the 501 allocated pages are migrated away to serve the contiguous request. 502 503 If unsure, say "n". 504 505config CMA_DEBUG 506 bool "CMA debug messages (DEVELOPMENT)" 507 depends on DEBUG_KERNEL && CMA 508 help 509 Turns on debug messages in CMA. This produces KERN_DEBUG 510 messages for every CMA call as well as various messages while 511 processing calls such as dma_alloc_from_contiguous(). 512 This option does not affect warning and error messages. 513 514config CMA_DEBUGFS 515 bool "CMA debugfs interface" 516 depends on CMA && DEBUG_FS 517 help 518 Turns on the DebugFS interface for CMA. 519 520config CMA_AREAS 521 int "Maximum count of the CMA areas" 522 depends on CMA 523 default 7 524 help 525 CMA allows to create CMA areas for particular purpose, mainly, 526 used as device private area. This parameter sets the maximum 527 number of CMA area in the system. 528 529 If unsure, leave the default value "7". 530 531config MEM_SOFT_DIRTY 532 bool "Track memory changes" 533 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 534 select PROC_PAGE_MONITOR 535 help 536 This option enables memory changes tracking by introducing a 537 soft-dirty bit on pte-s. This bit it set when someone writes 538 into a page just as regular dirty bit, but unlike the latter 539 it can be cleared by hands. 540 541 See Documentation/vm/soft-dirty.txt for more details. 542 543config ZSWAP 544 bool "Compressed cache for swap pages (EXPERIMENTAL)" 545 depends on FRONTSWAP && CRYPTO=y 546 select CRYPTO_LZO 547 select ZPOOL 548 default n 549 help 550 A lightweight compressed cache for swap pages. It takes 551 pages that are in the process of being swapped out and attempts to 552 compress them into a dynamically allocated RAM-based memory pool. 553 This can result in a significant I/O reduction on swap device and, 554 in the case where decompressing from RAM is faster that swap device 555 reads, can also improve workload performance. 556 557 This is marked experimental because it is a new feature (as of 558 v3.11) that interacts heavily with memory reclaim. While these 559 interactions don't cause any known issues on simple memory setups, 560 they have not be fully explored on the large set of potential 561 configurations and workloads that exist. 562 563config ZPOOL 564 tristate "Common API for compressed memory storage" 565 default n 566 help 567 Compressed memory storage API. This allows using either zbud or 568 zsmalloc. 569 570config ZBUD 571 tristate "Low (Up to 2x) density storage for compressed pages" 572 default n 573 help 574 A special purpose allocator for storing compressed pages. 575 It is designed to store up to two compressed pages per physical 576 page. While this design limits storage density, it has simple and 577 deterministic reclaim properties that make it preferable to a higher 578 density approach when reclaim will be used. 579 580config Z3FOLD 581 tristate "Up to 3x density storage for compressed pages" 582 depends on ZPOOL 583 default n 584 help 585 A special purpose allocator for storing compressed pages. 586 It is designed to store up to three compressed pages per physical 587 page. It is a ZBUD derivative so the simplicity and determinism are 588 still there. 589 590config ZSMALLOC 591 tristate "Memory allocator for compressed pages" 592 depends on MMU 593 default n 594 help 595 zsmalloc is a slab-based memory allocator designed to store 596 compressed RAM pages. zsmalloc uses virtual memory mapping 597 in order to reduce fragmentation. However, this results in a 598 non-standard allocator interface where a handle, not a pointer, is 599 returned by an alloc(). This handle must be mapped in order to 600 access the allocated space. 601 602config PGTABLE_MAPPING 603 bool "Use page table mapping to access object in zsmalloc" 604 depends on ZSMALLOC 605 help 606 By default, zsmalloc uses a copy-based object mapping method to 607 access allocations that span two pages. However, if a particular 608 architecture (ex, ARM) performs VM mapping faster than copying, 609 then you should select this. This causes zsmalloc to use page table 610 mapping rather than copying for object mapping. 611 612 You can check speed with zsmalloc benchmark: 613 https://github.com/spartacus06/zsmapbench 614 615config ZSMALLOC_STAT 616 bool "Export zsmalloc statistics" 617 depends on ZSMALLOC 618 select DEBUG_FS 619 help 620 This option enables code in the zsmalloc to collect various 621 statistics about whats happening in zsmalloc and exports that 622 information to userspace via debugfs. 623 If unsure, say N. 624 625config GENERIC_EARLY_IOREMAP 626 bool 627 628config MAX_STACK_SIZE_MB 629 int "Maximum user stack size for 32-bit processes (MB)" 630 default 80 631 range 8 256 if METAG 632 range 8 2048 633 depends on STACK_GROWSUP && (!64BIT || COMPAT) 634 help 635 This is the maximum stack size in Megabytes in the VM layout of 32-bit 636 user processes when the stack grows upwards (currently only on parisc 637 and metag arch). The stack will be located at the highest memory 638 address minus the given value, unless the RLIMIT_STACK hard limit is 639 changed to a smaller value in which case that is used. 640 641 A sane initial value is 80 MB. 642 643# For architectures that support deferred memory initialisation 644config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 645 bool 646 647config DEFERRED_STRUCT_PAGE_INIT 648 bool "Defer initialisation of struct pages to kthreads" 649 default n 650 depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT 651 depends on NO_BOOTMEM && MEMORY_HOTPLUG 652 depends on !FLATMEM 653 help 654 Ordinarily all struct pages are initialised during early boot in a 655 single thread. On very large machines this can take a considerable 656 amount of time. If this option is set, large machines will bring up 657 a subset of memmap at boot and then initialise the rest in parallel 658 by starting one-off "pgdatinitX" kernel thread for each node X. This 659 has a potential performance impact on processes running early in the 660 lifetime of the system until these kthreads finish the 661 initialisation. 662 663config IDLE_PAGE_TRACKING 664 bool "Enable idle page tracking" 665 depends on SYSFS && MMU 666 select PAGE_EXTENSION if !64BIT 667 help 668 This feature allows to estimate the amount of user pages that have 669 not been touched during a given period of time. This information can 670 be useful to tune memory cgroup limits and/or for job placement 671 within a compute cluster. 672 673 See Documentation/vm/idle_page_tracking.txt for more details. 674 675config ZONE_DEVICE 676 bool "Device memory (pmem, etc...) hotplug support" if EXPERT 677 depends on MEMORY_HOTPLUG 678 depends on MEMORY_HOTREMOVE 679 depends on SPARSEMEM_VMEMMAP 680 depends on X86_64 #arch_add_memory() comprehends device memory 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