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     rman, rman_activate_resource, rman_adjust_resource, rman_await_resource,
     rman_deactivate_resource, rman_fini, rman_init, rman_init_from_resource,
     rman_is_region_manager, rman_manage_region, rman_first_free_region, rman_last_free_region,
     rman_release_resource, rman_reserve_resource, rman_reserve_resource_bound,
     rman_make_alignment_flags, rman_get_start, rman_get_end, rman_get_device, rman_get_size,
     rman_get_flags, rman_set_virtual, rman_get_virtual, rman_set_bustag, rman_get_bustag,
     rman_set_bushandle, rman_get_bushandle, rman_set_rid, rman_get_rid — resource management


     #include <sys/types.h>
     #include <sys/rman.h>

     rman_activate_resource(struct resource *r);

     rman_adjust_resource(struct resource *r, u_long start, u_long end);

     rman_await_resource(struct resource *r, int pri2, int timo);

     rman_deactivate_resource(struct resource *r);

     rman_fini(struct rman *rm);

     rman_init(struct rman *rm);

     rman_init_from_resource(struct rman *rm, struct resource *r);

     rman_is_region_manager(struct resource *r, struct rman *rm);

     rman_manage_region(struct rman *rm, u_long start, u_long end);

     rman_first_free_region(struct rman *rm, u_long *start, u_long *end);

     rman_last_free_region(struct rman *rm, u_long *start, u_long *end);

     rman_release_resource(struct resource *r);

     struct resource *
     rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, u_int flags,
         struct device *dev);

     struct resource *
     rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end, u_long count,
         u_long bound, u_int flags, struct device *dev);

     rman_make_alignment_flags(uint32_t size);

     rman_get_start(struct resource *r);

     rman_get_end(struct resource *r);

     struct device *
     rman_get_device(struct resource *r);

     rman_get_size(struct resource *r);

     rman_get_flags(struct resource *r);

     rman_set_virtual(struct resource *r, void *v);

     void *
     rman_get_virtual(struct resource *r);

     rman_set_bustag(struct resource *r, bus_space_tag_t t);

     rman_get_bustag(struct resource *r);

     rman_set_bushandle(struct resource *r, bus_space_handle_t h);

     rman_get_bushandle(struct resource *r);

     rman_set_rid(struct resource *r, int rid);

     rman_get_rid(struct resource *r);


     The rman set of functions provides a flexible resource management abstraction.  It is used
     extensively by the bus management code.  It implements the abstractions of region and
     resource.  A region descriptor is used to manage a region; this could be memory or some
     other form of bus space.

     Each region has a set of bounds.  Within these bounds, allocated segments may reside.  Each
     segment, termed a resource, has several properties which are represented by a 16-bit flag
     register, as follows.

     #define RF_ALLOCATED    0x0001 /* resource has been reserved */
     #define RF_ACTIVE       0x0002 /* resource allocation has been activated */
     #define RF_SHAREABLE    0x0004 /* resource permits contemporaneous sharing */
     #define RF_FIRSTSHARE   0x0020 /* first in sharing list */
     #define RF_PREFETCHABLE 0x0040 /* resource is prefetchable */

     Bits 15:10  of the flag register are used to represent the desired alignment of the resource
     within the region.

     The rman_init() function initializes the region descriptor, pointed to by the rm argument,
     for use with the resource management functions.  It is required that the fields rm_type and
     rm_descr of struct rman be set before calling rman_init().  The field rm_type shall be set
     to RMAN_ARRAY.  The field rm_descr shall be set to a string that describes the resource to
     be managed.  The rm_start and rm_end fields may be set to limit the range of acceptable
     resource addresses.  If these fields are not set, rman_init() will initialize them to allow
     the entire range of resource addresses.  It also initializes any mutexes associated with the
     structure.  If rman_init() fails to initialize the mutex, it will return ENOMEM; otherwise
     it will return 0 and rm will be initialized.

     The rman_fini() function frees any structures associated with the structure pointed to by
     the rm argument.  If any of the resources within the managed region have the RF_ALLOCATED
     flag set, it will return EBUSY; otherwise, any mutexes associated with the structure will be
     released and destroyed, and the function will return 0.

     The rman_manage_region() function establishes the concept of a region which is under rman
     control.  The rman argument points to the region descriptor.  The start and end arguments
     specify the bounds of the region.  If successful, rman_manage_region() will return 0.  If
     the region overlaps with an existing region, it will return EBUSY.  If any part of the
     region falls outside of the valid address range for rm, it will return EINVAL.  ENOMEM will
     be returned when rman_manage_region() failed to allocate memory for the region.

     The rman_init_from_resource() function is a wrapper routine to create a resource manager
     backed by an existing resource.  It initializes rm using rman_init() and then adds a region
     to rm corresponding to the address range allocated to r via rman_manage_region().

     The rman_first_free_region() and rman_last_free_region() functions can be used to query a
     resource manager for its first (or last) unallocated region.  If rm contains no free region,
     these functions will return ENOENT.  Otherwise, *start and *end are set to the bounds of the
     free region and zero is returned.

     The rman_reserve_resource_bound() function is where the bulk of the rman logic is located.
     It attempts to reserve a contiguous range in the specified region rm for the use of the
     device dev.  The caller can specify the start and end of an acceptable range, as well as a
     boundary restriction and required aligment, and the code will attempt to find a free segment
     which fits.  The start argument is the lowest acceptable starting value of the resource.
     The end argument is the highest acceptable ending value of the resource.  Therefore, start +
     count - 1 must be ≤ end for any allocation to happen.  The aligment requirement (if any) is
     specified in flags.  The bound argument may be set to specify a boundary restriction such
     that an allocated region may cross an address that is a multiple of the boundary.  The bound
     argument must be a power of two.  It may be set to zero to specify no boundary restriction.
     A shared segment will be allocated if the RF_SHAREABLE flag is set, otherwise an exclusive
     segment will be allocated.  If this shared segment already exists, the caller has its device
     added to the list of consumers.

     The rman_reserve_resource() function is used to reserve resources within a previously
     established region.  It is a simplified interface to rman_reserve_resource_bound() which
     passes 0 for the bound argument.

     The rman_make_alignment_flags() function returns the flag mask corresponding to the desired
     alignment size.  This should be used when calling rman_reserve_resource_bound().

     The rman_is_region_manager() function returns true if the allocated resource r was allocated
     from rm.  Otherwise, it returns false.

     The rman_adjust_resource() function is used to adjust the reserved address range of an
     allocated resource to reserve start through end.  It can be used to grow or shrink one or
     both ends of the resource range.  The current implementation does not support entirely
     relocating the resource and will fail with EINVAL if the new resource range does not overlap
     the old resource range.  If either end of the resource range grows and the new resource
     range would conflict with another allocated resource, the function will fail with EBUSY.
     The rman_adjust_resource() function does not support adjusting the resource range for shared
     resources and will fail such attempts with EINVAL.  Upon success, the resource r will have a
     start address of start and an end address of end and the function will return zero.  Note
     that none of the constraints of the original allocation request such as alignment or
     boundary restrictions are checked by rman_adjust_resource().  It is the caller's
     responsibility to enforce any such requirements.

     The rman_release_resource() function releases the reserved resource r.  It may attempt to
     merge adjacent free resources.

     The rman_activate_resource() function marks a resource as active, by setting the RF_ACTIVE
     flag.  If this is a time shared resource, and the caller has not yet acquired the resource,
     the function returns EBUSY.

     The rman_deactivate_resource() function marks a resource r as inactive, by clearing the
     RF_ACTIVE flag.  If other consumers are waiting for this range, it will wakeup their

     The rman_await_resource() function performs an asynchronous wait for a resource r to become
     inactive, that is, for the RF_ACTIVE flag to be cleared.  It is used to enable cooperative
     sharing of a resource which can only be safely used by one thread at a time.  The arguments
     pri and timo are passed to the rman_await_resource() function.

     The rman_get_start(), rman_get_end(), rman_get_size(), and rman_get_flags() functions return
     the bounds, size and flags of the previously reserved resource r.

     The rman_set_bustag() function associates a bus_space_tag_t t with the resource r.  The
     rman_get_bustag() function is used to retrieve this tag once set.

     The rman_set_bushandle() function associates a bus_space_handle_t h with the resource r.
     The rman_get_bushandle() function is used to retrieve this handle once set.

     The rman_set_virtual() function is used to associate a kernel virtual address with a
     resource r.  The rman_get_virtual() function can be used to retrieve the KVA once set.

     The rman_set_rid() function associates a resource identifier with a resource r.  The
     rman_get_rid() function retrieves this RID.

     The rman_get_device() function returns a pointer to the device which reserved the resource


     bus_activate_resource(9), bus_adjust_resource(9), bus_alloc_resource(9),
     bus_release_resource(9), bus_set_resource(9), mutex(9)


     This manual page was written by Bruce M Simpson <>.