The functions and symbols related to memory allocation follow.
#include <linux/malloc.h>
,
void *kmalloc(size_t size, int flags);
,
void kfree(void *obj);
#include <linux/mm.h>
,
GFP_KERNEL
,
GFP_ATOMIC
,
__GFP_DMA
,
__GFP_HIGHMEM
kmalloc flags.
__GFP_DMA
and
__GFP_HIGHMEM
are flags that can be OR’d to
either GFP_KERNEL
or GFP_ATOMIC
.
#include <linux/malloc.h>
,
kmem_cache_t *kmem_cache_create(char *name, size_t size, size_t offset, unsigned long flags, constructor(), destructor());
,
int kmem_cache_destroy(kmem_cache_t *cache);
Create and destroy a slab cache. The cache can be used to allocate several objects of the same size.
SLAB_NO_REAP
,
SLAB_HWCACHE_ALIGN
,
SLAB_CACHE_DMA
SLAB_CTOR_ATOMIC
,
SLAB_CTOR_CONSTRUCTOR
Flags that the allocator can pass to the constructor and the destructor functions.
void *kmem_cache_alloc(kmem_cache_t *cache, int flags);
,
void kmem_cache_free(kmem_cache_t *cache, const void *obj);
unsigned long get_zeroed_page(int flags);
,
unsigned long __get_free_page(int flags);
,
unsigned long __get_free_pages(int flags, unsigned long order);
,
unsigned long __get_dma_pages(int flags, unsigned long order);
The page-oriented allocation functions.
get_zeroed_page returns a single, zero-filled
page. All the other versions of the call do not initialize the
contents of the returned page(s).
__get_dma_pages is only a compatibility
macro in Linux 2.2 and later (you can use
__GFP_DMA
instead).
void free_page(unsigned long addr);
,
void free_pages(unsigned long addr, unsigned long order);
#include <linux/vmalloc.h>
,
void * vmalloc(unsigned long size);
,
void vfree(void * addr);
,
#include <asm/io.h>
,
void * ioremap(unsigned long offset, unsigned long size);
,
void iounmap(void *addr);
These functions allocate or free a contiguous virtual address space. ioremap accesses physical memory through virtual addresses, while vmalloc allocates free pages. Regions mapped with ioremap are freed with iounmap, while pages obtained from vmalloc are released with vfree.
#include <linux/bootmem.h>
,
void *alloc_bootmem(unsigned long size);
,
void *alloc_bootmem_low(unsigned long size);
,
void *alloc_bootmem_pages(unsigned long size);
,
void *alloc_bootmem_low_pages(unsigned long size);
Only with version 2.4 of the kernel, memory can be allocated at boot time using these functions. The facility can only be used by drivers directly linked in the kernel image.