table of contents
|CONTIGMALLOC(9)||Kernel Developer's Manual||CONTIGMALLOC(9)|
NAME¶contigmalloc, contigfree — manage contiguous kernel physical memory
#include <sys/malloc.h> void *
contigmalloc(unsigned long size, struct malloc_type *type, int flags, vm_paddr_t low, vm_paddr_t high, unsigned long alignment, unsigned long boundary); void
contigfree(void *addr, unsigned long size, struct malloc_type *type);
DESCRIPTION¶The contigmalloc() function allocates size bytes of contiguous physical memory that is aligned to alignment bytes, and which does not cross a boundary of boundary bytes. If successful, the allocation will reside between physical addresses low and high. The returned pointer points to a wired kernel virtual address range of size bytes allocated from the kernel virtual address (KVA) map. The flags parameter modifies contigmalloc()'s behaviour as follows:
- Causes the allocated physical memory to be zero filled.
- Causes contigmalloc() to return
NULLif the request cannot be immediately fulfilled due to resource shortage.
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_NOWAITis 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
void *p; p = contigmalloc(8192, M_DEVBUF, M_ZERO, 0, (1L << 22), 32 * 1024, 1024 * 1024);
DIAGNOSTICS¶The contigmalloc() function will panic if size is zero, or if alignment or boundary is not a power of two.
SEE ALSO¶malloc(9), memguard(9)
|July 19, 2007||Debian|