1.\" $NetBSD: uvm.9,v 1.13 2000/05/07 17:09:32 mrg Exp $ 2.\" 3.\" Copyright (c) 1998 Matthew R. Green 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 22.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 24.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" XXX this manual sets nS to 1 or 0 in the description, to obtain 30.\" synopsis-like function prototypes. any better way? 31.\" 32.Dd March 26, 2000 33.Dt UVM 9 34.Os 35.Sh NAME 36.Nm uvm 37.Nd virtual memory system external interface 38.Sh SYNOPSIS 39.Fd #include <sys/param.h> 40.Fd #include <vm/vm.h> 41.Fd #include <uvm/uvm.h> 42.Sh DESCRIPTION 43The UVM virtual memory system manages access to the computer's memory 44resources. User processes and the kernel access these resources through 45UVM's external interface. UVM's external interface includes functions that: 46.Pp 47.Bl -hyphen -compact 48.It 49initialise UVM sub-systems 50.It 51manage virtual address spaces 52.It 53resolve page faults 54.It 55memory map files and devices 56.It 57perform uio-based I/O to virtual memory 58.It 59allocate and free kernel virtual memory 60.It 61allocate and free physical memory 62.El 63.Pp 64In addition to exporting these services, UVM has two kernel-level processes: 65pagedaemon and swapper. The pagedaemon process sleeps until physical memory 66becomes scarce. When that happens, pagedaemon is awoken. It scans physical 67memory, paging out and freeing memory that has not been recently used. The 68swapper process swaps in runnable processes that are currently swapped out, 69if there is room. 70.Pp 71There are also several miscellaneous functions. 72.Sh INITIALISATION 73.nr nS 1 74.Pp 75.Ft void 76.Fn uvm_init 77.Ft void 78.Fn uvm_init_limits "struct proc *p" 79.Ft void 80.Fn uvm_setpagesize 81.Ft void 82.Fn uvm_swap_init 83.nr nS 0 84.Pp 85.Fn uvm_init 86sets up the UVM system at system boot time, after the 87copyright has been printed. It initialises 88global state, the page, map, kernel virtual memory state, 89machine-dependent physical map, kernel memory allocator, 90pager and anonymous memory sub-systems, and then enables 91paging of kernel objects. 92.Pp 93.Fn uvm_init_limits 94initialises process limits for the named process. This is for use by 95the system startup for process zero, before any other processes are 96created. 97.Pp 98.Fn uvm_setpagesize 99initialises the uvmexp members pagesize (if not already done by 100machine-dependent code), pageshift and pagemask. It should be called by 101machine-dependent code early in the 102.Xr pmap_init 9 103call. 104.Pp 105.Fn uvm_swap_init 106initialises the swap sub-system. 107.Sh VIRTUAL ADDRESS SPACE MANAGEMENT 108.Pp 109.nr nS 1 110.Ft int 111.Fn uvm_map "vm_map_t map" "vaddr_t *startp" "vsize_t size" "struct uvm_object *uobj" "voff_t uoffset" "uvm_flag_t flags" 112.Ft int 113.Fn uvm_map_pageable "vm_map_t map" "vaddr_t start" "vaddr_t end" "boolean_t new_pageable" 114.Ft boolean_t 115.Fn uvm_map_checkprot "vm_map_t map" "vaddr_t start" "vaddr_t end" "vm_prot_t protection" 116.Ft int 117.Fn uvm_map_protect "vm_map_t map" "vaddr_t start" "vaddr_t end" "vm_prot_t new_prot" "boolean_t set_max" 118.Ft int 119.Fn uvm_deallocate "vm_map_t map" "vaddr_t start" "vsize_t size" 120 121.Ft struct vmspace * 122.Fn uvmspace_alloc "vaddr_t min" "vaddr_t max" "int pageable" 123.Ft void 124.Fn uvmspace_exec "struct proc *p" 125.Ft struct vmspace * 126.Fn uvmspace_fork "struct vmspace *vm" 127.Ft void 128.Fn uvmspace_free "struct vmspace *vm1" 129.Ft void 130.Fn uvmspace_share "struct proc *p1" "struct proc *p2" 131.Ft void 132.Fn uvmspace_unshare "struct proc *p" 133.nr nS 0 134.Pp 135.Fn uvm_map 136establishes a valid mapping in map 137.Fa map , 138which must be unlocked. The new mapping has size 139.Fa size , 140which must be in 141.Dv PAGE_SIZE 142units. The 143.Fa uobj 144and 145.Fa uoffset 146arguments can have four meanings. When 147.Fa uobj 148is 149.Dv NULL 150and 151.Fa uoffset 152is 153.Dv UVM_UNKNOWN_OFFSET , 154.Fn uvm_map 155does not use the machine-dependant 156.Dv PMAP_PREFER 157function. If 158.Fa uoffset 159is any other value, it is used as the hint to 160.Dv PMAP_PREFER . 161When 162.Fa uobj 163is not 164.Dv NULL 165and 166.Fa uoffset 167is 168.Dv UVM_UNKNOWN_OFFSET , 169.Fn uvm_map 170finds the offset based upon the virtual address, passed as 171.Fa startp . 172If 173.Fa uoffset 174is any other value, we are doing a normal mapping at this offset. The 175start address of the map will be returned in 176.Fa startp . 177.Pp 178.Fa flags 179passed to 180.Fn uvm_map 181are typically created using the 182.Fn UVM_MAPFLAG "vm_prot_t prot" "vm_prot_t maxprot" "vm_inherit_t inh" "int advice" "int flags" 183macro, which uses the following values. 184The 185.Fa prot 186and 187.Fa maxprot 188can take are: 189.Bd -literal 190#define UVM_PROT_MASK 0x07 /* protection mask */ 191#define UVM_PROT_NONE 0x00 /* protection none */ 192#define UVM_PROT_ALL 0x07 /* everything */ 193#define UVM_PROT_READ 0x01 /* read */ 194#define UVM_PROT_WRITE 0x02 /* write */ 195#define UVM_PROT_EXEC 0x04 /* exec */ 196#define UVM_PROT_R 0x01 /* read */ 197#define UVM_PROT_W 0x02 /* write */ 198#define UVM_PROT_RW 0x03 /* read-write */ 199#define UVM_PROT_X 0x04 /* exec */ 200#define UVM_PROT_RX 0x05 /* read-exec */ 201#define UVM_PROT_WX 0x06 /* write-exec */ 202#define UVM_PROT_RWX 0x07 /* read-write-exec */ 203.Ed 204.Pp 205The values that 206.Fa inh 207can take are: 208.Bd -literal 209#define UVM_INH_MASK 0x30 /* inherit mask */ 210#define UVM_INH_SHARE 0x00 /* "share" */ 211#define UVM_INH_COPY 0x10 /* "copy" */ 212#define UVM_INH_NONE 0x20 /* "none" */ 213#define UVM_INH_DONATE 0x30 /* "donate" << not used */ 214.Ed 215.Pp 216The values that 217.Fa advice 218can take are: 219.Bd -literal 220#define UVM_ADV_NORMAL 0x0 /* 'normal' */ 221#define UVM_ADV_RANDOM 0x1 /* 'random' */ 222#define UVM_ADV_SEQUENTIAL 0x2 /* 'sequential' */ 223#define UVM_ADV_MASK 0x7 /* mask */ 224.Ed 225.Pp 226The values that 227.Fa flags 228can take are: 229.Bd -literal 230#define UVM_FLAG_FIXED 0x010000 /* find space */ 231#define UVM_FLAG_OVERLAY 0x020000 /* establish overlay */ 232#define UVM_FLAG_NOMERGE 0x040000 /* don't merge map entries */ 233#define UVM_FLAG_COPYONW 0x080000 /* set copy_on_write flag */ 234#define UVM_FLAG_AMAPPAD 0x100000 /* for bss: pad amap to reduce malloc() */ 235#define UVM_FLAG_TRYLOCK 0x200000 /* fail if we can not lock map */ 236.Ed 237.Pp 238The 239.Dv UVM_MAPFLAG 240macro arguments can be combined with an or operator. There are 241several special purpose macros for checking protection combinations, e.g. the 242.Dv UVM_PROT_WX 243macro. There are also some additional macros to extract bits from 244the flags. The 245.Dv UVM_PROTECTION , 246.Dv UVM_INHERIT , 247.Dv UVM_MAXPROTECTION 248and 249.Dv UVM_ADVICE 250macros return the protection, inheritance, maximum protection and advice, 251respectively. 252.Fn uvm_map 253returns a standard UVM return value. 254.Pp 255.Fn uvm_map_pageable 256changes the pageability of the pages in the range from 257.Fa start 258to 259.Fa end 260in map 261.Fa map 262to 263.Fa new_pageable . 264.Fn uvm_map_pageable 265returns a standard UVM return value. 266.Pp 267.Fn uvm_map_checkprot 268checks the protection of the range from 269.Fa start 270to 271.Fa end 272in map 273.Fa map 274against 275.Fa protection . 276This returns either 277.Dv TRUE 278or 279.Dv FALSE . 280.Pp 281.Fn uvm_map_protect 282changes the protection 283.Fa start 284to 285.Fa end 286in map 287.Fa map 288to 289.Fa new_prot , 290also setting the maximum protection to the region to 291.Fa new_prot 292if 293.Fa set_max 294is non-zero. This function returns a standard UVM return value. 295.Pp 296.Fn uvm_deallocate 297deallocates kernel memory in map 298.Fa map 299from address 300.Fa start 301to 302.Fa start + size . 303.Pp 304.Fn uvmspace_alloc 305allocates and returns a new address space, with ranges from 306.Fa min 307to 308.Fa max , 309setting the pageability of the address space to 310.Fa pageable. 311.Pp 312.Fn uvmspace_exec 313either reuses the address space of process 314.Fa p 315if there are no other references to it, or creates 316a new one with 317.Fn uvmspace_alloc . 318.Pp 319.Fn uvmspace_fork 320creates and returns a new address space based upon the 321.Fa vm1 322address space, typically used when allocating an address space for a 323child process. 324.Pp 325.Fn uvmspace_free 326lowers the reference count on the address space 327.Fa vm , 328freeing the data structures if there are no other references. 329.Pp 330.Fn uvmspace_share 331causes process 332.Pa p2 333to share the address space of 334.Fa p1 . 335.Pp 336.Fn uvmspace_unshare 337ensures that process 338.Fa p 339has its own, unshared address space, by creating a new one if 340necessary by calling 341.Fn uvmspace_fork . 342.Sh PAGE FAULT HANDLING 343.Pp 344.nr nS 1 345.Ft int 346.Fn uvm_fault "vm_map_t orig_map" "vaddr_t vaddr" "vm_fault_t fault_type" "vm_prot_t access_type" 347.nr nS 0 348.Pp 349.Fn uvm_fault 350is the main entry point for faults. It takes 351.Fa orig_map 352as the map the fault originated in, a 353.Fa vaddr 354offset into the map the fault occured, 355.Fa fault_type 356describing the type of fault, and 357.Fa access_type 358describing the type of access requested. 359.Fn uvm_fault 360returns a standard UVM return value. 361.Sh MEMORY MAPPING FILES AND DEVICES 362.Pp 363.nr nS 1 364.Ft struct uvm_object * 365.Fn uvn_attach "void *arg" "vm_prot_t accessprot" 366.Ft void 367.Fn uvm_vnp_setsize "struct vnode *vp" "u_quad_t newsize" 368.Ft void 369.Fn uvm_vnp_sync "struct mount *mp" 370.Ft void 371.Fn uvm_vnp_terminate "struct vnode *vp" 372.Ft boolean_t 373.Fn uvm_vnp_uncache "struct vnode *vp" 374.nr nS 0 375.Pp 376.Fn uvn_attach 377attaches a UVM object to vnode 378.Fa arg , 379creating the object if necessary. The object is returned. 380.Pp 381.Fn uvm_vnp_setsize 382sets the size of vnode 383.Fa vp 384to 385.Fa newsize . 386Caller must hold a reference to the vnode. If the vnode shrinks, pages 387no longer used are discarded. This function will be removed when the 388filesystem and VM buffer caches are merged. 389.Pp 390.Fn uvm_vnp_sync 391flushes dirty vnodes from either the mount point passed in 392.Fa mp , 393or all dirty vnodes if 394.Fa mp 395is 396.Dv NULL . 397This function will be removed when the filesystem and VM buffer caches 398are merged. 399.Pp 400.Fn uvm_vnp_terminate 401frees all VM resources allocated to vnode 402.Fa vp . 403If the vnode still has references, it will not be destroyed; however 404all future operations using this vnode will fail. This function will be 405removed when the filesystem and VM buffer caches are merged. 406.Pp 407.Fn uvm_vnp_uncache 408disables vnode 409.Fa vp 410from persisting when all references are freed. This function will be 411removed when the file-system and UVM caches are unified. Returns 412true if there is no active vnode. 413.Sh VIRTUAL MEMORY I/O 414.Pp 415.nr nS 1 416.Ft int 417.Fn uvm_io "vm_map_t map" "struct uio *uio" 418.nr nS 0 419.Pp 420.Fn uvm_io 421performs the I/O described in 422.Fa uio 423on the memory described in 424.Fa map . 425.Sh ALLOCATION OF KERNEL MEMORY 426.Pp 427.nr nS 1 428.Ft vaddr_t 429.Fn uvm_km_alloc "vm_map_t map" "vsize_t size" 430.Ft vaddr_t 431.Fn uvm_km_zalloc "vm_map_t map" "vsize_t size" 432.Ft vaddr_t 433.Fn uvm_km_alloc1 "vm_map_t map" "vsize_t size" "boolean_t zeroit" 434.Ft vaddr_t 435.Fn uvm_km_kmemalloc "vm_map_t map" "struct uvm_object *obj" "vsize_t size" "int flags" 436.Ft vaddr_t 437.Fn uvm_km_valloc "vm_map_t map" "vsize_t size" 438.Ft vaddr_t 439.Fn uvm_km_valloc_wait "vm_map_t map" "vsize_t size" 440.Ft struct vm_map * 441.Fn uvm_km_suballoc "vm_map_t map" "vaddr_t *min" "vaddr_t *max " "vsize_t size" "boolean_t pageable" "boolean_t fixed" "vm_map_t submap" 442.Ft void 443.Fn uvm_km_free "vm_map_t map" "vaddr_t addr" "vsize_t size" 444.Ft void 445.Fn uvm_km_free_wakeup "vm_map_t map" "vaddr_t addr" "vsize_t size" 446.nr nS 0 447.Pp 448.Fn uvm_km_alloc 449and 450.Fn uvm_km_zalloc 451allocate 452.Fa size 453bytes of wired kernel memory in map 454.Fa map . 455In addition to allocation, 456.Fn uvm_km_zalloc 457zeros the memory. Both of these functions are defined as macros in 458terms of 459.Fn uvm_km_alloc1 , 460and should almost always be used in preference to 461.Fn uvm_km_alloc1 . 462.Pp 463.Fn uvm_km_alloc1 464allocates and returns 465.Fa size 466bytes of wired memory in the kernel map, zeroing the memory if the 467.Fa zeroit 468argument is non-zero. 469.Pp 470.Fn uvm_km_kmemalloc 471allocates and returns 472.Fa size 473bytes of wired kernel memory into 474.Fa obj . 475The flags can be any of: 476.Bd -literal 477#define UVM_KMF_NOWAIT 0x1 /* matches M_NOWAIT */ 478#define UVM_KMF_VALLOC 0x2 /* allocate VA only */ 479#define UVM_KMF_TRYLOCK UVM_FLAG_TRYLOCK /* try locking only */ 480.Ed 481.Pp 482.Dv UVM_KMF_NOWAIT 483causes 484.Fn uvm_km_kmemalloc 485to return immediately if no memory is available. 486.Dv UVM_KMF_VALLOC 487causes no pages to be allocated, only a virtual address. 488.Dv UVM_KMF_TRYLOCK 489causes 490.Fn uvm_km_kmemalloc 491to use 492.Fn simple_lock_try 493when locking maps. 494.Pp 495.Fn uvm_km_valloc 496and 497.Fn uvm_km_valloc_wait 498return a newly allocated zero-filled address in the kernel map of size 499.Fa size . 500.Fn uvm_km_valloc_wait 501will also wait for kernel memory to become available, if there is a 502memory shortage. 503.Sh ALLOCATION OF PHYSICAL MEMORY 504.Pp 505.nr nS 1 506.Ft struct vm_page * 507.Fn uvm_pagealloc "struct uvm_object *uobj" "voff_t off" "struct vm_anon *anon" 508.Ft void 509.Fn uvm_pagerealloc "struct vm_page *pg" "struct uvm_object *newobj" "voff_t newoff" 510.Ft void 511.Fn uvm_pagefree "struct vm_page *pg" 512.Ft int 513.Fn uvm_pglistalloc "psize_t size" "paddr_t low" "paddr_t high" "paddr_t alignment" "paddr_t boundary" "struct pglist *rlist" "int nsegs" "int waitok" 514.Ft void 515.Fn uvm_pglistfree "struct pglist *list" 516.Ft void 517.Fn uvm_page_physload "vaddr_t start" "vaddr_t end" "vaddr_t avail_start" "vaddr_t avail_end" 518.nr nS 0 519.Pp 520.Fn uvm_pagealloc 521allocates a page of memory at virtual address 522.Fa off 523in either the object 524.Fa uobj 525or the anonymous memory 526.Fa anon , 527which must be locked by the caller. Only one of 528.Fa off 529and 530.Fa uobj 531can be non 532.Dv NULL . 533Returns 534.Dv NULL 535when no page can be found. 536.Pp 537.Fn uvm_pagerealloc 538reallocates page 539.Fa pg 540to a new object 541.Fa newobj , 542at a new offset 543.Fa newoff . 544.Pp 545.Fn uvm_pagefree 546free's the physical page 547.Fa pg . 548.Pp 549.Fn uvm_pglistalloc 550allocates a list of pages for size 551.Fa size 552byte under various constraints. 553.Fa low 554and 555.Fa high 556describe the lowest and highest addresses acceptable for the list. If 557.Fa alignment 558is non-zero, it describes the required alignment of the list, in 559power-of-two notation. If 560.Fa boundary 561is non-zero, no segment of the list may cross this power-of-two 562boundary, relative to zero. 563The 564.Fa nsegs 565and 566.Fa waitok 567arguments are currently ignored. 568.Pp 569.Fn uvm_pglistfree 570frees the list of pages pointed to by 571.Fa list . 572.Pp 573.Fn uvm_page_physload 574loads physical memory segments into VM space. It must be called at system 575boot time to setup physical memory management pages. The arguments describe 576the 577.Fa start 578and 579.Fa end 580of the physical addresses of the segment, and the available start and end 581addresses of pages not already in use. 582.\" XXX expand on "system boot time"! 583.Pp 584.Fn uvm_km_suballoc 585allocates submap from 586.Fa map , 587creating a new map if 588.Fa submap 589is 590.Dv NULL . 591The addresses of the submap can be specified exactly by setting the 592.Fa fixed 593argument to non-zero, which causes the 594.Fa min 595argument specify the beginning of the address in thes submap. If 596.Fa fixed 597is zero, any address of size 598.Fa size 599will be allocated from 600.Fa map 601and the start and end addresses returned in 602.Fa min 603and 604.Fa max . 605If 606.Fa pageable 607is non-zero, entries in the map may be paged out. 608.Pp 609.Fn uvm_km_free 610and 611.Fn uvm_km_free_wakeup 612free 613.Fa size 614bytes of memory in the kernal map, starting at address 615.Fa addr . 616.Fn uvm_km_free_wakeup 617calls 618.Fn thread_wakeup 619on the map before unlocking the map. 620.Sh PROCESSES 621.Pp 622.nr nS 1 623.Ft void 624.Fn uvm_pageout 625.Ft void 626.Fn uvm_scheduler 627.Ft void 628.Fn uvm_swapin "struct proc *p" 629.nr nS 0 630.Pp 631.Fn uvm_pageout 632is the main loop for the page daemon. 633.Pp 634.Fn uvm_scheduler 635is the process zero main loop, which is to be called after the 636system has finished starting other processes. It handles the 637swapping in of runnable, swapped out processes in priority 638order. 639.Pp 640.Fn uvm_swapin 641swaps in the named process. 642.Sh MISCELLANEOUS FUNCTIONS 643.nr nS 1 644.Pp 645.Ft struct uvm_object * 646.Fn uao_create "vsize_t size" "int flags" 647.Ft void 648.Fn uao_detach "struct uvm_object *uobj" 649.Ft void 650.Fn uao_reference "struct uvm_object *uobj" 651 652.Ft boolean_t 653.Fn uvm_chgkprot "caddr_t addr" "size_t len" "int rw" 654.Ft void 655.Fn uvm_kernacc "caddr_t addr" "size_t len" "int rw" 656.Ft boolean_t 657.Fn uvm_useracc "caddr_t addr" "size_t len" "int rw" 658 659.Ft void 660.Fn uvm_vslock "struct proc *p" "caddr_t addr" "size_t len" 661.Ft void 662.Fn uvm_vsunlock "struct proc *p" "caddr_t addr" "size_t len" 663 664.Ft void 665.Fn uvm_meter 666.Ft int 667.Fn uvm_sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp " "size_t newlen" "struct proc *p" 668 669.Ft void 670.Fn uvm_fork "struct proc *p1" "struct proc *p2" "boolean_t shared" 671.Ft int 672.Fn uvm_grow "struct proc *p" "vaddr_t sp" 673.Ft int 674.Fn uvm_coredump "struct proc *p" "struct vnode *vp" "struct ucred *cred" "struct core *chdr" 675.nr nS 0 676.Pp 677The 678.Fn uao_create , 679.Fn uao_detach 680and 681.Fn uao_reference 682functions operate on anonymous memory objects, such as those used to support 683System V shared memory. 684.Fn uao_create 685returns an object of size 686.Fa size 687with flags: 688.Bd -literal 689#define UAO_FLAG_KERNOBJ 0x1 /* create kernel object */ 690#define UAO_FLAG_KERNSWAP 0x2 /* enable kernel swap */ 691.Pp 692.Ed 693which can only be used once each at system boot time. 694.Fn uao_reference 695creates an additional reference to the named anonymous memory object. 696.Fn uao_detach 697removes a reference from the named anonymous memory object, destroying 698it if removing the last reference. 699.Pp 700.Fn uvm_chgkprot 701changes the protection of kernel memory from 702.Fa addr 703to 704.Fa addr + len 705to the value of 706.Fa rw . 707This is primarily useful for debuggers, for setting breakpoints. 708This function is only available with options 709.Dv KGDB . 710.Pp 711.Fn uvm_kernacc 712and 713.Fn uvm_useracc 714check the access at address 715.Fa addr 716to 717.Fa addr + len 718for 719.Fa rw 720access, in the kernel address space, and the current process' 721address space respectively. 722.Pp 723.Fn uvm_vslock 724and 725.Fn uvm_vsunlock 726control the wiring and unwiring of pages for process 727.Fa p 728from 729.Fa addr 730to 731.Fa addr + len . 732These functions are normally used to wire memory for I/O. 733.Pp 734.Fn uvm_meter 735calculates the load average and wakes up the swapper if necessary. 736.Pp 737.Fn uvm_sysctl 738provides support for the 739.Dv CTL_VM 740domain of the 741.Xr sysctl 3 742hierarchy. 743.Fn uvm_sysctl 744handles the 745.Dv VM_LOADAVG , 746.Dv VM_METER 747and 748.Dv VM_UVMEXP 749calls, which return the current load averages, calculates current VM 750totals, and returns the uvmexp structure respectively. The load averages 751are access from userland using the 752.Xr getloadavg 3 753function. The uvmexp structure has all global state of the UVM system, 754and has the following members: 755.Bd -literal 756/* vm_page constants */ 757int pagesize; /* size of a page (PAGE_SIZE): must be power of 2 */ 758int pagemask; /* page mask */ 759int pageshift; /* page shift */ 760 761/* vm_page counters */ 762int npages; /* number of pages we manage */ 763int free; /* number of free pages */ 764int active; /* number of active pages */ 765int inactive; /* number of pages that we free'd but may want back */ 766int paging; /* number of pages in the process of being paged out */ 767int wired; /* number of wired pages */ 768int reserve_pagedaemon; /* number of pages reserved for pagedaemon */ 769int reserve_kernel; /* number of pages reserved for kernel */ 770 771/* pageout params */ 772int freemin; /* min number of free pages */ 773int freetarg; /* target number of free pages */ 774int inactarg; /* target number of inactive pages */ 775int wiredmax; /* max number of wired pages */ 776 777/* swap */ 778int nswapdev; /* number of configured swap devices in system */ 779int swpages; /* number of PAGE_SIZE'ed swap pages */ 780int swpginuse; /* number of swap pages in use */ 781int nswget; /* number of times fault calls uvm_swap_get() */ 782int nanon; /* number total of anon's in system */ 783int nfreeanon; /* number of free anon's */ 784 785/* stat counters */ 786int faults; /* page fault count */ 787int traps; /* trap count */ 788int intrs; /* interrupt count */ 789int swtch; /* context switch count */ 790int softs; /* software interrupt count */ 791int syscalls; /* system calls */ 792int pageins; /* pagein operation count */ 793 /* pageouts are in pdpageouts below */ 794int swapins; /* swapins */ 795int swapouts; /* swapouts */ 796int pgswapin; /* pages swapped in */ 797int pgswapout; /* pages swapped out */ 798int forks; /* forks */ 799int forks_ppwait; /* forks where parent waits */ 800int forks_sharevm; /* forks where vmspace is shared */ 801 802/* fault subcounters */ 803int fltnoram; /* number of times fault was out of ram */ 804int fltnoanon; /* number of times fault was out of anons */ 805int fltpgwait; /* number of times fault had to wait on a page */ 806int fltpgrele; /* number of times fault found a released page */ 807int fltrelck; /* number of times fault relock called */ 808int fltrelckok; /* number of times fault relock is a success */ 809int fltanget; /* number of times fault gets anon page */ 810int fltanretry; /* number of times fault retrys an anon get */ 811int fltamcopy; /* number of times fault clears "needs copy" */ 812int fltnamap; /* number of times fault maps a neighbor anon page */ 813int fltnomap; /* number of times fault maps a neighbor obj page */ 814int fltlget; /* number of times fault does a locked pgo_get */ 815int fltget; /* number of times fault does an unlocked get */ 816int flt_anon; /* number of times fault anon (case 1a) */ 817int flt_acow; /* number of times fault anon cow (case 1b) */ 818int flt_obj; /* number of times fault is on object page (2a) */ 819int flt_prcopy; /* number of times fault promotes with copy (2b) */ 820int flt_przero; /* number of times fault promotes with zerofill (2b) */ 821 822/* daemon counters */ 823int pdwoke; /* number of times daemon woke up */ 824int pdrevs; /* number of times daemon rev'd clock hand */ 825int pdswout; /* number of times daemon called for swapout */ 826int pdfreed; /* number of pages daemon freed since boot */ 827int pdscans; /* number of pages daemon scaned since boot */ 828int pdanscan; /* number of anonymous pages scanned by daemon */ 829int pdobscan; /* number of object pages scanned by daemon */ 830int pdreact; /* number of pages daemon reactivated since boot */ 831int pdbusy; /* number of times daemon found a busy page */ 832int pdpageouts; /* number of times daemon started a pageout */ 833int pdpending; /* number of times daemon got a pending pagout */ 834int pddeact; /* number of pages daemon deactivates */ 835.Ed 836.Pp 837.Fn uvm_fork 838forks a virtual address space for process' (old) 839.Fa p1 840and (new) 841.Fa p2 . 842If the 843.Fa shared 844argument is non zero, p1 shares its address space with p2, 845otherwise a new address space is created. This function 846currently has no return value, and thus cannot fail. In 847the future, this function will changed to allowed it to 848fail in low memory conditions. 849.Pp 850.Fn uvm_grow 851increases the stack segment of process 852.Fa p 853to include 854.Fa sp . 855.Pp 856.Fn uvm_coredump 857generates a coredump on vnode 858.Fa vp 859for process 860.Fa p 861with credentials 862.Fa cred 863and core header description in 864.Fa chdr . 865.Sh STANDARD UVM RETURN VALUES 866This section documents the standard return values that callers of UVM 867functions can expect. They are derived from the Mach VM values 868of the same function. The full list of values can be seen below. 869.Bd -literal 870#define KERN_SUCCESS 0 871#define KERN_INVALID_ADDRESS 1 872#define KERN_PROTECTION_FAILURE 2 873#define KERN_NO_SPACE 3 874#define KERN_INVALID_ARGUMENT 4 875#define KERN_FAILURE 5 876#define KERN_RESOURCE_SHORTAGE 6 877#define KERN_NOT_RECEIVER 7 878#define KERN_NO_ACCESS 8 879#define KERN_PAGES_LOCKED 9 880.Ed 881.Pp 882Note that 883.Dv KERN_NOT_RECEIVER 884and 885.Dv KERN_PAGES_LOCKED 886values are not actually returned by the UVM code. 887.Sh NOTES 888These functions are only available with options 889.Dv UVM . 890.Pp 891.Fn uvm_chgkprot 892is only available if the kernel has been compiled with options 893.Dv KGDB . 894.Pp 895The include file 896.Pa <vm/vm.h> 897will be deprecated when then Mach VM system is obsoleted. All structure 898and types whose names begin with ``vm_'' will be renamed to ``uvm_''. 899.Pp 900The 901.Xr pmap 9 902manual page is not yet written. 903.Sh HISTORY 904UVM is a new VM system developed at Washington University in St. Louis 905(Missouri). UVM's roots lie partly in the Mach-based 906.Bx 4.4 907VM system, the FreeBSD VM system, and the SunOS4 VM system. UVM's basic 908structure is based on the 909.Bx 4.4 910VM system. UVM's new i386 machine-depenent layer includes several ideas 911from FreeBSD. UVM's new anonymous memory system is based on the 912anonymous memory system found in SunOS4 VM (as described in papers by 913published Sun Microsystems, Inc.). UVM also includes a number of feature 914new to BSD including page loanout, map entry passing, simplified 915copy-on-write, and clustered anonymous memory pageout. UVM will be 916further documented in August 1998 in a dissertation by Charles D. Cranor. 917.Pp 918UVM appeared in 919.Nx 1.4 . 920.Sh AUTHOR 921Charles D. Cranor <chuck@ccrc.wustl.edu> designed and implemented UVM. 922.Pp 923Matthew Green <mrg@eterna.com.au> wrote the swap-space management code 924and handled the logistical issues involed with merging UVM into the 925NetBSD source tree. 926.Pp 927Chuck Silvers <chuq@chuq.com> implemented the aobj pager, thus allowing 928UVM to support System V shared memory and process swapping. 929.Sh SEE ALSO 930.Xr getloadavg 3 , 931.Xr kvm 3 , 932.Xr sysctl 3 , 933.Xr ddb 4 , 934.Xr options 4 935