VMALLOC_32(9) Memory Management in Linux VMALLOC_32(9)NAME
vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
void * vmalloc_32(unsigned long size);
Allocate enough 32bit PA addressable pages to cover size from the page level allocator and map them into contiguous kernel virtual space.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 VMALLOC_32(9)
Check Out this Related Man Page
CONTIGMALLOC(9) BSD Kernel Developer's Manual CONTIGMALLOC(9)NAME
contigmalloc, contigfree -- manage contiguous kernel physical memory
contigmalloc(unsigned long size, struct malloc_type *type, int flags, vm_paddr_t low, vm_paddr_t high, unsigned long alignment,
unsigned long boundary);
contigfree(void *addr, unsigned long size, struct malloc_type *type);
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:
M_ZERO Causes the allocated physical memory to be zero filled.
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().
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
The contigmalloc() function returns a kernel virtual address if allocation succeeds, or NULL otherwise.
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 cross-
ing a 1M address boundary.
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)BSD July 19, 2007 BSD
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