UVM_MAP(9)             NetBSD Kernel Developer's Manual             UVM_MAP(9)

NAME
     uvm_map -- virtual address space management interface

SYNOPSIS
     #include <sys/param.h>
     #include <uvm/uvm.h>

     int
     uvm_map(struct vm_map *map, vaddr_t *startp, vsize_t size,
         struct uvm_object *uobj, voff_t uoffset, vsize_t align,
         uvm_flag_t flags);

     void
     uvm_unmap(struct vm_map *map, vaddr_t start, vaddr_t end);

     int
     uvm_map_pageable(struct vm_map *map, vaddr_t start, vaddr_t end,
         bool new_pageable, int lockflags);

     bool
     uvm_map_checkprot(struct vm_map *map, vaddr_t start, vaddr_t end,
         vm_prot_t protection);

     int
     uvm_map_protect(struct vm_map *map, vaddr_t start, vaddr_t end,
         vm_prot_t new_prot, bool set_max);

     int
     uvm_deallocate(struct vm_map *map, vaddr_t start, vsize_t size);

     struct vmspace *
     uvmspace_alloc(vaddr_t min, vaddr_t max);

     void
     uvmspace_exec(struct lwp *l, vaddr_t start, vaddr_t end);

     struct vmspace *
     uvmspace_fork(struct vmspace *vm);

     void
     uvmspace_free(struct vmspace *vm);

     void
     uvmspace_share(struct proc *p1, struct proc *p2);

     vaddr_t
     uvm_uarea_alloc(void);

     void
     uvm_uarea_free(vaddr_t uaddr);

     vaddr_t
     uvm_uarea_system_alloc(void);

     void
     uvm_uarea_system_free(vaddr_t uaddr);

DESCRIPTION
     The UVM facility for virtual address space management.

FUNCTIONS
     uvm_map() establishes a valid mapping in map map, which must be unlocked.
     The new mapping has size size, which must be a multiple of PAGE_SIZE.
     The uobj and uoffset arguments can have four meanings.  When uobj is NULL
     and uoffset is UVM_UNKNOWN_OFFSET, uvm_map() does not use the machine-
     dependent PMAP_PREFER function.  If uoffset is any other value, it is
     used as the hint to PMAP_PREFER.  When uobj is not NULL and uoffset is
     UVM_UNKNOWN_OFFSET, uvm_map() finds the offset based upon the virtual
     address, passed as startp.  If uoffset is any other value, then a regular
     mapping is performed at this offset.  The start address of the map will
     be returned in startp.

     align specifies alignment of mapping unless UVM_FLAG_FIXED is specified
     in flags.  align must be a power of 2.

     flags passed to uvm_map() are typically created using the
     UVM_MAPFLAG(vm_prot_t prot, vm_prot_t maxprot, vm_inherit_t inh, int
     advice, int flags) macro, which uses the following values.  The prot and
     maxprot can take are:

     UVM_PROT_NONE       No protection bits.

     UVM_PROT_R          Read.

     UVM_PROT_W          Write.

     UVM_PROT_X          Exec.

     UVM_PROT_MASK       Mask to extraction the protection bits.

     Additionally, the following constants for ORed values are available:
     UVM_PROT_RW, UVM_PROT_RX, UVM_PROT_WX and UVM_PROT_RWX.

     The values that inh can take are:

     UVM_INH_SHARE       Share the map.

     UVM_INH_COPY        Copy the map.

     UVM_INH_NONE        No inheritance.

     UVM_INH_MASK        Mark to extract inherit flags.

     The values that advice can take are:

     UVM_ADV_NORMAL      "Normal" use.

     UVM_ADV_RANDOM      "Random" access likelyhood.

     UVM_ADV_SEQUENTIAL  "Sequential" access likelyhood.

     UVM_ADV_MASK        Mask to extract the advice flags.

     The values that flags can take are:

     UVM_FLAG_FIXED      Attempt to map on the address specified by startp.
                         Otherwise, it is used just as a hint.

     UVM_FLAG_OVERLAY    Establish overlay.

     UVM_FLAG_NOMERGE    Do not merge map entries, if such merge is possible.

     UVM_FLAG_COPYONW    Use copy-on-write i.e. do not fault in the pages
                         immediately.

     UVM_FLAG_AMAPPAD    User for BSS: alocate larger amap, if extending is
                         likely.

     UVM_FLAG_TRYLOCK    Fail if cannot acquire the lock immediately.

     UVM_FLAG_NOWAIT     Not allowed to sleep.  Fail, in such case.

     UVM_FLAG_QUANTUM    Indicates that map entry cannot be split once mapped.

     UVM_FLAG_WAITVA     Sleep until VA space is available, if it is not.

     UVM_FLAG_VAONLY     Unmap only VA space.  Used by uvm_unmap().

     The UVM_MAPFLAG macro arguments can be combined with an or operator.
     There are several special purpose macros for checking protection combina-
     tions, e.g., the UVM_PROT_WX.  There are also some additional macros to
     extract bits from the flags.  The UVM_PROTECTION, UVM_INHERIT,
     UVM_MAXPROTECTION and UVM_ADVICE macros return the protection, inheri-
     tance, maximum protection and advice, respectively.  uvm_map() returns
     zero on success or error number otherwise.

     uvm_unmap() removes a valid mapping, from start to end, in map map, which
     must be unlocked.

     uvm_map_pageable() changes the pageability of the pages in the range from
     start to end in map map to new_pageable.  uvm_map_pageable() returns zero
     on success or error number otherwise.

     uvm_map_checkprot() checks the protection of the range from start to end
     in map map against protection.  This returns either true or false.

     uvm_map_protect() changes the protection start to end in map map to
     new_prot, also setting the maximum protection to the region to new_prot
     if set_max is true.  This function returns a standard UVM return value.

     uvm_deallocate() deallocates kernel memory in map map from address start
     to start + size.

     uvmspace_alloc() allocates and returns a new address space, with ranges
     from min to max.

     uvmspace_exec() either reuses the address space of thread l (its process)
     if there are no other references to it, or creates a new one with
     uvmspace_alloc().  The range of valid addresses in the address space is
     reset to start through end.

     uvmspace_fork() creates and returns a new address space based upon the vm
     address space, typically used when allocating an address space for a
     child process.

     uvmspace_free() lowers the reference count on the address space vm, free-
     ing the data structures if there are no other references.

     uvmspace_share() causes process p2 to share the address space of p1.

     uvm_uarea_alloc() allocates memory for a u-area (i.e. kernel stack, PCB,
     etc) and returns the address.

     uvm_uarea_free() frees a u-area allocated with uvm_uarea_alloc().

     uvm_uarea_system_alloc() and uvm_uarea_system_free() are optimised rou-
     tines, which are used for kernel threads.

SEE ALSO
     pmap(9), uvm(9), uvm_km(9), vmem(9)

HISTORY
     UVM and uvm_map first appeared in NetBSD 1.4.

NetBSD 6.0                       June 3, 2011                       NetBSD 6.0

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