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 ARCH_ENABLE_THP_MIGRATION 266 bool 267 268config PHYS_ADDR_T_64BIT 269 def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT 270 271config BOUNCE 272 bool "Enable bounce buffers" 273 default y 274 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM) 275 help 276 Enable bounce buffers for devices that cannot access 277 the full range of memory available to the CPU. Enabled 278 by default when ZONE_DMA or HIGHMEM is selected, but you 279 may say n to override this. 280 281# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often 282# have more than 4GB of memory, but we don't currently use the IOTLB to present 283# a 32-bit address to OHCI. So we need to use a bounce pool instead. 284config NEED_BOUNCE_POOL 285 bool 286 default y if TILE && USB_OHCI_HCD 287 288config NR_QUICK 289 int 290 depends on QUICKLIST 291 default "1" 292 293config VIRT_TO_BUS 294 bool 295 help 296 An architecture should select this if it implements the 297 deprecated interface virt_to_bus(). All new architectures 298 should probably not select this. 299 300 301config MMU_NOTIFIER 302 bool 303 select SRCU 304 305config KSM 306 bool "Enable KSM for page merging" 307 depends on MMU 308 help 309 Enable Kernel Samepage Merging: KSM periodically scans those areas 310 of an application's address space that an app has advised may be 311 mergeable. When it finds pages of identical content, it replaces 312 the many instances by a single page with that content, so 313 saving memory until one or another app needs to modify the content. 314 Recommended for use with KVM, or with other duplicative applications. 315 See Documentation/vm/ksm.txt for more information: KSM is inactive 316 until a program has madvised that an area is MADV_MERGEABLE, and 317 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 318 319config DEFAULT_MMAP_MIN_ADDR 320 int "Low address space to protect from user allocation" 321 depends on MMU 322 default 4096 323 help 324 This is the portion of low virtual memory which should be protected 325 from userspace allocation. Keeping a user from writing to low pages 326 can help reduce the impact of kernel NULL pointer bugs. 327 328 For most ia64, ppc64 and x86 users with lots of address space 329 a value of 65536 is reasonable and should cause no problems. 330 On arm and other archs it should not be higher than 32768. 331 Programs which use vm86 functionality or have some need to map 332 this low address space will need CAP_SYS_RAWIO or disable this 333 protection by setting the value to 0. 334 335 This value can be changed after boot using the 336 /proc/sys/vm/mmap_min_addr tunable. 337 338config ARCH_SUPPORTS_MEMORY_FAILURE 339 bool 340 341config MEMORY_FAILURE 342 depends on MMU 343 depends on ARCH_SUPPORTS_MEMORY_FAILURE 344 bool "Enable recovery from hardware memory errors" 345 select MEMORY_ISOLATION 346 select RAS 347 help 348 Enables code to recover from some memory failures on systems 349 with MCA recovery. This allows a system to continue running 350 even when some of its memory has uncorrected errors. This requires 351 special hardware support and typically ECC memory. 352 353config HWPOISON_INJECT 354 tristate "HWPoison pages injector" 355 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 356 select PROC_PAGE_MONITOR 357 358config NOMMU_INITIAL_TRIM_EXCESS 359 int "Turn on mmap() excess space trimming before booting" 360 depends on !MMU 361 default 1 362 help 363 The NOMMU mmap() frequently needs to allocate large contiguous chunks 364 of memory on which to store mappings, but it can only ask the system 365 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 366 more than it requires. To deal with this, mmap() is able to trim off 367 the excess and return it to the allocator. 368 369 If trimming is enabled, the excess is trimmed off and returned to the 370 system allocator, which can cause extra fragmentation, particularly 371 if there are a lot of transient processes. 372 373 If trimming is disabled, the excess is kept, but not used, which for 374 long-term mappings means that the space is wasted. 375 376 Trimming can be dynamically controlled through a sysctl option 377 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 378 excess pages there must be before trimming should occur, or zero if 379 no trimming is to occur. 380 381 This option specifies the initial value of this option. The default 382 of 1 says that all excess pages should be trimmed. 383 384 See Documentation/nommu-mmap.txt for more information. 385 386config TRANSPARENT_HUGEPAGE 387 bool "Transparent Hugepage Support" 388 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE 389 select COMPACTION 390 select RADIX_TREE_MULTIORDER 391 help 392 Transparent Hugepages allows the kernel to use huge pages and 393 huge tlb transparently to the applications whenever possible. 394 This feature can improve computing performance to certain 395 applications by speeding up page faults during memory 396 allocation, by reducing the number of tlb misses and by speeding 397 up the pagetable walking. 398 399 If memory constrained on embedded, you may want to say N. 400 401choice 402 prompt "Transparent Hugepage Support sysfs defaults" 403 depends on TRANSPARENT_HUGEPAGE 404 default TRANSPARENT_HUGEPAGE_ALWAYS 405 help 406 Selects the sysfs defaults for Transparent Hugepage Support. 407 408 config TRANSPARENT_HUGEPAGE_ALWAYS 409 bool "always" 410 help 411 Enabling Transparent Hugepage always, can increase the 412 memory footprint of applications without a guaranteed 413 benefit but it will work automatically for all applications. 414 415 config TRANSPARENT_HUGEPAGE_MADVISE 416 bool "madvise" 417 help 418 Enabling Transparent Hugepage madvise, will only provide a 419 performance improvement benefit to the applications using 420 madvise(MADV_HUGEPAGE) but it won't risk to increase the 421 memory footprint of applications without a guaranteed 422 benefit. 423endchoice 424 425config ARCH_WANTS_THP_SWAP 426 def_bool n 427 428config THP_SWAP 429 def_bool y 430 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP 431 help 432 Swap transparent huge pages in one piece, without splitting. 433 XXX: For now this only does clustered swap space allocation. 434 435 For selection by architectures with reasonable THP sizes. 436 437config TRANSPARENT_HUGE_PAGECACHE 438 def_bool y 439 depends on TRANSPARENT_HUGEPAGE 440 441# 442# UP and nommu archs use km based percpu allocator 443# 444config NEED_PER_CPU_KM 445 depends on !SMP 446 bool 447 default y 448 449config CLEANCACHE 450 bool "Enable cleancache driver to cache clean pages if tmem is present" 451 default n 452 help 453 Cleancache can be thought of as a page-granularity victim cache 454 for clean pages that the kernel's pageframe replacement algorithm 455 (PFRA) would like to keep around, but can't since there isn't enough 456 memory. So when the PFRA "evicts" a page, it first attempts to use 457 cleancache code to put the data contained in that page into 458 "transcendent memory", memory that is not directly accessible or 459 addressable by the kernel and is of unknown and possibly 460 time-varying size. And when a cleancache-enabled 461 filesystem wishes to access a page in a file on disk, it first 462 checks cleancache to see if it already contains it; if it does, 463 the page is copied into the kernel and a disk access is avoided. 464 When a transcendent memory driver is available (such as zcache or 465 Xen transcendent memory), a significant I/O reduction 466 may be achieved. When none is available, all cleancache calls 467 are reduced to a single pointer-compare-against-NULL resulting 468 in a negligible performance hit. 469 470 If unsure, say Y to enable cleancache 471 472config FRONTSWAP 473 bool "Enable frontswap to cache swap pages if tmem is present" 474 depends on SWAP 475 default n 476 help 477 Frontswap is so named because it can be thought of as the opposite 478 of a "backing" store for a swap device. The data is stored into 479 "transcendent memory", memory that is not directly accessible or 480 addressable by the kernel and is of unknown and possibly 481 time-varying size. When space in transcendent memory is available, 482 a significant swap I/O reduction may be achieved. When none is 483 available, all frontswap calls are reduced to a single pointer- 484 compare-against-NULL resulting in a negligible performance hit 485 and swap data is stored as normal on the matching swap device. 486 487 If unsure, say Y to enable frontswap. 488 489config CMA 490 bool "Contiguous Memory Allocator" 491 depends on HAVE_MEMBLOCK && MMU 492 select MIGRATION 493 select MEMORY_ISOLATION 494 help 495 This enables the Contiguous Memory Allocator which allows other 496 subsystems to allocate big physically-contiguous blocks of memory. 497 CMA reserves a region of memory and allows only movable pages to 498 be allocated from it. This way, the kernel can use the memory for 499 pagecache and when a subsystem requests for contiguous area, the 500 allocated pages are migrated away to serve the contiguous request. 501 502 If unsure, say "n". 503 504config CMA_DEBUG 505 bool "CMA debug messages (DEVELOPMENT)" 506 depends on DEBUG_KERNEL && CMA 507 help 508 Turns on debug messages in CMA. This produces KERN_DEBUG 509 messages for every CMA call as well as various messages while 510 processing calls such as dma_alloc_from_contiguous(). 511 This option does not affect warning and error messages. 512 513config CMA_DEBUGFS 514 bool "CMA debugfs interface" 515 depends on CMA && DEBUG_FS 516 help 517 Turns on the DebugFS interface for CMA. 518 519config CMA_AREAS 520 int "Maximum count of the CMA areas" 521 depends on CMA 522 default 7 523 help 524 CMA allows to create CMA areas for particular purpose, mainly, 525 used as device private area. This parameter sets the maximum 526 number of CMA area in the system. 527 528 If unsure, leave the default value "7". 529 530config MEM_SOFT_DIRTY 531 bool "Track memory changes" 532 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 533 select PROC_PAGE_MONITOR 534 help 535 This option enables memory changes tracking by introducing a 536 soft-dirty bit on pte-s. This bit it set when someone writes 537 into a page just as regular dirty bit, but unlike the latter 538 it can be cleared by hands. 539 540 See Documentation/vm/soft-dirty.txt for more details. 541 542config ZSWAP 543 bool "Compressed cache for swap pages (EXPERIMENTAL)" 544 depends on FRONTSWAP && CRYPTO=y 545 select CRYPTO_LZO 546 select ZPOOL 547 default n 548 help 549 A lightweight compressed cache for swap pages. It takes 550 pages that are in the process of being swapped out and attempts to 551 compress them into a dynamically allocated RAM-based memory pool. 552 This can result in a significant I/O reduction on swap device and, 553 in the case where decompressing from RAM is faster that swap device 554 reads, can also improve workload performance. 555 556 This is marked experimental because it is a new feature (as of 557 v3.11) that interacts heavily with memory reclaim. While these 558 interactions don't cause any known issues on simple memory setups, 559 they have not be fully explored on the large set of potential 560 configurations and workloads that exist. 561 562config ZPOOL 563 tristate "Common API for compressed memory storage" 564 default n 565 help 566 Compressed memory storage API. This allows using either zbud or 567 zsmalloc. 568 569config ZBUD 570 tristate "Low (Up to 2x) density storage for compressed pages" 571 default n 572 help 573 A special purpose allocator for storing compressed pages. 574 It is designed to store up to two compressed pages per physical 575 page. While this design limits storage density, it has simple and 576 deterministic reclaim properties that make it preferable to a higher 577 density approach when reclaim will be used. 578 579config Z3FOLD 580 tristate "Up to 3x density storage for compressed pages" 581 depends on ZPOOL 582 default n 583 help 584 A special purpose allocator for storing compressed pages. 585 It is designed to store up to three compressed pages per physical 586 page. It is a ZBUD derivative so the simplicity and determinism are 587 still there. 588 589config ZSMALLOC 590 tristate "Memory allocator for compressed pages" 591 depends on MMU 592 default n 593 help 594 zsmalloc is a slab-based memory allocator designed to store 595 compressed RAM pages. zsmalloc uses virtual memory mapping 596 in order to reduce fragmentation. However, this results in a 597 non-standard allocator interface where a handle, not a pointer, is 598 returned by an alloc(). This handle must be mapped in order to 599 access the allocated space. 600 601config PGTABLE_MAPPING 602 bool "Use page table mapping to access object in zsmalloc" 603 depends on ZSMALLOC 604 help 605 By default, zsmalloc uses a copy-based object mapping method to 606 access allocations that span two pages. However, if a particular 607 architecture (ex, ARM) performs VM mapping faster than copying, 608 then you should select this. This causes zsmalloc to use page table 609 mapping rather than copying for object mapping. 610 611 You can check speed with zsmalloc benchmark: 612 https://github.com/spartacus06/zsmapbench 613 614config ZSMALLOC_STAT 615 bool "Export zsmalloc statistics" 616 depends on ZSMALLOC 617 select DEBUG_FS 618 help 619 This option enables code in the zsmalloc to collect various 620 statistics about whats happening in zsmalloc and exports that 621 information to userspace via debugfs. 622 If unsure, say N. 623 624config GENERIC_EARLY_IOREMAP 625 bool 626 627config MAX_STACK_SIZE_MB 628 int "Maximum user stack size for 32-bit processes (MB)" 629 default 80 630 range 8 256 if METAG 631 range 8 2048 632 depends on STACK_GROWSUP && (!64BIT || COMPAT) 633 help 634 This is the maximum stack size in Megabytes in the VM layout of 32-bit 635 user processes when the stack grows upwards (currently only on parisc 636 and metag arch). The stack will be located at the highest memory 637 address minus the given value, unless the RLIMIT_STACK hard limit is 638 changed to a smaller value in which case that is used. 639 640 A sane initial value is 80 MB. 641 642config DEFERRED_STRUCT_PAGE_INIT 643 bool "Defer initialisation of struct pages to kthreads" 644 default n 645 depends on NO_BOOTMEM 646 depends on !FLATMEM 647 help 648 Ordinarily all struct pages are initialised during early boot in a 649 single thread. On very large machines this can take a considerable 650 amount of time. If this option is set, large machines will bring up 651 a subset of memmap at boot and then initialise the rest in parallel 652 by starting one-off "pgdatinitX" kernel thread for each node X. This 653 has a potential performance impact on processes running early in the 654 lifetime of the system until these kthreads finish the 655 initialisation. 656 657config IDLE_PAGE_TRACKING 658 bool "Enable idle page tracking" 659 depends on SYSFS && MMU 660 select PAGE_EXTENSION if !64BIT 661 help 662 This feature allows to estimate the amount of user pages that have 663 not been touched during a given period of time. This information can 664 be useful to tune memory cgroup limits and/or for job placement 665 within a compute cluster. 666 667 See Documentation/vm/idle_page_tracking.txt for more details. 668 669# arch_add_memory() comprehends device memory 670config ARCH_HAS_ZONE_DEVICE 671 bool 672 673config ZONE_DEVICE 674 bool "Device memory (pmem, HMM, etc...) hotplug support" 675 depends on MEMORY_HOTPLUG 676 depends on MEMORY_HOTREMOVE 677 depends on SPARSEMEM_VMEMMAP 678 depends on ARCH_HAS_ZONE_DEVICE 679 select RADIX_TREE_MULTIORDER 680 681 help 682 Device memory hotplug support allows for establishing pmem, 683 or other device driver discovered memory regions, in the 684 memmap. This allows pfn_to_page() lookups of otherwise 685 "device-physical" addresses which is needed for using a DAX 686 mapping in an O_DIRECT operation, among other things. 687 688 If FS_DAX is enabled, then say Y. 689 690config ARCH_HAS_HMM 691 bool 692 default y 693 depends on (X86_64 || PPC64) 694 depends on ZONE_DEVICE 695 depends on MMU && 64BIT 696 depends on MEMORY_HOTPLUG 697 depends on MEMORY_HOTREMOVE 698 depends on SPARSEMEM_VMEMMAP 699 700config MIGRATE_VMA_HELPER 701 bool 702 703config HMM 704 bool 705 select MIGRATE_VMA_HELPER 706 707config HMM_MIRROR 708 bool "HMM mirror CPU page table into a device page table" 709 depends on ARCH_HAS_HMM 710 select MMU_NOTIFIER 711 select HMM 712 help 713 Select HMM_MIRROR if you want to mirror range of the CPU page table of a 714 process into a device page table. Here, mirror means "keep synchronized". 715 Prerequisites: the device must provide the ability to write-protect its 716 page tables (at PAGE_SIZE granularity), and must be able to recover from 717 the resulting potential page faults. 718 719config DEVICE_PRIVATE 720 bool "Unaddressable device memory (GPU memory, ...)" 721 depends on ARCH_HAS_HMM 722 select HMM 723 724 help 725 Allows creation of struct pages to represent unaddressable device 726 memory; i.e., memory that is only accessible from the device (or 727 group of devices). You likely also want to select HMM_MIRROR. 728 729config DEVICE_PUBLIC 730 bool "Addressable device memory (like GPU memory)" 731 depends on ARCH_HAS_HMM 732 select HMM 733 734 help 735 Allows creation of struct pages to represent addressable device 736 memory; i.e., memory that is accessible from both the device and 737 the CPU 738 739config FRAME_VECTOR 740 bool 741 742config ARCH_USES_HIGH_VMA_FLAGS 743 bool 744config ARCH_HAS_PKEYS 745 bool 746 747config PERCPU_STATS 748 bool "Collect percpu memory statistics" 749 default n 750 help 751 This feature collects and exposes statistics via debugfs. The 752 information includes global and per chunk statistics, which can 753 be used to help understand percpu memory usage. 754 755config GUP_BENCHMARK 756 bool "Enable infrastructure for get_user_pages_fast() benchmarking" 757 default n 758 help 759 Provides /sys/kernel/debug/gup_benchmark that helps with testing 760 performance of get_user_pages_fast(). 761 762 See tools/testing/selftests/vm/gup_benchmark.c 763