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contigfree (9)

>> contigfree (9) ( FreeBSD man: Ядро )

BSD mandoc

NAME



contigmalloc , contigfree

 - manage contiguous kernel physical memory

SYNOPSIS

#include <sys/types.h>
#include <sys/malloc.h>
void * Fo contigmalloc Fa unsigned long size Fa struct malloc_type *type Fa int flags Fa vm_paddr_t low Fa vm_paddr_t high Fa unsigned long alignment Fa unsigned long boundary Fc Ft void Fo contigfree Fa void *addr Fa unsigned long size Fa struct malloc_type *type Fc

DESCRIPTION

The contigmalloc ();
function allocates Fa size bytes of contiguous physical memory that is aligned to Fa alignment bytes, and which does not cross a boundary of Fa boundary bytes. If successful, the allocation will reside between physical addresses Fa low and Fa high . The returned pointer points to a wired kernel virtual address range of Fa size bytes allocated from the kernel virtual address (KVA) map.

The Fa flags parameter modifies contigmalloc (Ns 's);
behaviour as follows:

M_ZERO: Causes the allocated physical memory to be zero filled.
M_NOWAIT: Causes contigmalloc ();
to return NULL if the request cannot be immediately fulfilled due to resource shortage.

Other flags (if present) are ignored.

The contigfree ();
function deallocates memory allocated by a previous call to contigmalloc (.);

IMPLEMENTATION NOTES

The contigmalloc ();
function does not sleep waiting for memory resources to be freed up, but instead actively reclaims pages before giving up. However, unless M_NOWAIT is specified, it may select a page for reclamation that must first be written to backing storage, causing it to sleep.

RETURN VALUES

The contigmalloc ();
function returns a kernel virtual address if allocation succeeds, or NULL otherwise.

EXAMPLES

void *p;
p = contigmalloc(8192, M_DEVBUF, M_ZERO, 0, (1L << 22),
    32 * 1024, 1024 * 1024);

Ask for 8192 bytes of zero-filled memory residing between physical address 0 and 4194303 inclusive, aligned to a 32K boundary and not crossing a 1M address boundary.