RMFREE(9F) Kernel Functions for Drivers RMFREE(9F)

NAME

rmfree - free space back into a resource map

SYNOPSIS

#include <sys/map.h>
#include <sys/ddi.h>


void rmfree(struct map *mp, size_t size, ulong_t index);

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

mp
Pointer to the map structure.


size
Number of units being freed.


index
Index of the first unit of the allocated resource.

DESCRIPTION

The rmfree() function releases space back into a resource map. It is
the opposite of rmalloc(9F), which allocates space that is controlled
by a resource map structure.


When releasing resources using rmfree() the size and index passed to
rmfree() must exactly match the size and index values passed to and
returned from a previous call to rmalloc(). Resources cannot be
returned piecemeal.


Drivers may define resource maps for resource allocation, in terms of
arbitrary units, using the rmallocmap(9F) function. The system
maintains the resource map structure by size and index, computed in
units appropriate for the resource. For example, units may be byte
addresses, pages of memory, or blocks. rmfree() frees up unallocated
space for re-use.


The rmfree() function can also be used to initialize a resource map,
in which case the size and index should cover the entire resource
area.

CONTEXT

The rmfree() function can be called from user, interrupt, or kernel
context.

SEE ALSO

rmalloc(9F), rmalloc_wait(9F), rmallocmap(9F), rmfreemap(9F)


Writing Device Drivers

January 16, 2006 RMFREE(9F)