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

vmem_create, vmem_xcreate, vmem_destroy
create and destroy vmem arenas

#include <sys/vmem.h>

typedef struct vmem vmem_t;
typedef void *(vmem_alloc_t)(vmem_t *, size_t, int);
typedef void (vmem_free_t)(vmem_t *, void *, size_t);
typedef void *(vmem_ximport_t)(vmem_t *, size_t *, size_t, int);

vmem_t *
vmem_create(const char *name, void *base, size_t size, size_t quantum, vmem_alloc_t *afunc, vmem_free_t *ffunc, vmem_t *source, size_t qcache_max, int vmflag);

vmem_t *
vmem_xcreate(const char *name, void *base, size_t size, size_t quantum, vmem_ximport_t *afunc, vmem_free_t *ffunc, vmem_t *source, size_t qcache_max, int vmflag);

void
vmem_destroy(vmem_t *vmp);

illumos DDI specific

name
A character string giving a name to the vmem arena to be created.
base
An address indicating the lowest possible value in the arena.
size
The size of the arena to create.
quantum
The arena's “quantum”. The granularity of the arena. The amount allocated at minimum by each request. Must be a power of 2.
afunc
A function which is called to import new spans from source, which may be NULL if this arena does not import from another. When calling vmem_create(), afunc is a vmem_alloc_t, a function taking three parameters and returning a pointer to void (the imported space):
vmem_t *
The source arena from which we'll import. The source argument to vmem_create().
size_t
The size to import.
int
The vmflag argument used for the import.

When calling vmem_xcreate(), afunc is a vmem_ximport_t, a function taking four parameters and returning a pointer to void (the imported space):

vmem_t *
The source arena from which we'll import. The source argument to vmem_xcreate().
size_t *
The size of the import. afunc may increase this size if that is desirable, but must never decrease it.
size_t
The desired alignment of the imported space.
int
The vmflag argument used for the import.
ffunc
A function which is called to return spans to source, which may be NULL if this arena does not import from another. This is a vmem_free_t, a function taking three parameters and returning void:
vmem_t
The arena to which space is being returned. The source argument to vmem_create() or vmem_xcreate().
void *
The span being returned to the source arena.
size_t
The size of the span being returned to the source arena.
source
An arena from which this arena will import, which may be NULL if this arena does not import from another.
qcache_max
Each arena offers caching of integer multiples of quantum up to qcache_max, which may be 0.
vmflag
A bitmask of flags indicating the characteristics of this arena.
The arena represents arbitrary integer identifiers, rather than virtual memory.
vmp
A pointer to the vmem arena to be destroyed.

A vmem arena is a section of an arbitrary address space (a range of integer addresses). This commonly represents virtual memory, but can in fact be an arbitrary set of integers. The VMC_IDENTIFIER flag set at arena creation time differentiates between these two cases.

The afunc, ffunc, and source arguments combine to support a hierarchical structure of arenas, each importing from a single parent (the source). The vmem_create() and vmem_xcreate() functions differ in that the latter provides an interface for afunc to alter the size of the span imported from source. It is only legal to increase this size.

These functions can be called from user or kernel context.

Upon successful completion the vmem_create() and vmem_xcreate() functions return a pointer to a vmem arena. Otherwise, NULL is returned to indicate the arena could not be created.

vmem(9), vmem_add(9F), vmem_alloc(9F)
January 18, 2017 OmniOS