diff options
Diffstat (limited to 'mm/bootmem.c')
| -rw-r--r-- | mm/bootmem.c | 159 |
1 files changed, 55 insertions, 104 deletions
diff --git a/mm/bootmem.c b/mm/bootmem.c index 9e197987b67d..97db0e8e362b 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -21,6 +21,53 @@ #include "internal.h" +/** + * DOC: bootmem overview + * + * Bootmem is a boot-time physical memory allocator and configurator. + * + * It is used early in the boot process before the page allocator is + * set up. + * + * Bootmem is based on the most basic of allocators, a First Fit + * allocator which uses a bitmap to represent memory. If a bit is 1, + * the page is allocated and 0 if unallocated. To satisfy allocations + * of sizes smaller than a page, the allocator records the Page Frame + * Number (PFN) of the last allocation and the offset the allocation + * ended at. Subsequent small allocations are merged together and + * stored on the same page. + * + * The information used by the bootmem allocator is represented by + * :c:type:`struct bootmem_data`. An array to hold up to %MAX_NUMNODES + * such structures is statically allocated and then it is discarded + * when the system initialization completes. Each entry in this array + * corresponds to a node with memory. For UMA systems only entry 0 is + * used. + * + * The bootmem allocator is initialized during early architecture + * specific setup. Each architecture is required to supply a + * :c:func:`setup_arch` function which, among other tasks, is + * responsible for acquiring the necessary parameters to initialise + * the boot memory allocator. These parameters define limits of usable + * physical memory: + * + * * @min_low_pfn - the lowest PFN that is available in the system + * * @max_low_pfn - the highest PFN that may be addressed by low + * memory (%ZONE_NORMAL) + * * @max_pfn - the last PFN available to the system. + * + * After those limits are determined, the :c:func:`init_bootmem` or + * :c:func:`init_bootmem_node` function should be called to initialize + * the bootmem allocator. The UMA case should use the `init_bootmem` + * function. It will initialize ``contig_page_data`` structure that + * represents the only memory node in the system. In the NUMA case the + * `init_bootmem_node` function should be called to initialize the + * bootmem allocator for each node. + * + * Once the allocator is set up, it is possible to use either single + * node or NUMA variant of the allocation APIs. + */ + #ifndef CONFIG_NEED_MULTIPLE_NODES struct pglist_data __refdata contig_page_data = { .bdata = &bootmem_node_data[0] @@ -62,6 +109,8 @@ static unsigned long __init bootmap_bytes(unsigned long pages) /** * bootmem_bootmap_pages - calculate bitmap size in pages * @pages: number of pages the bitmap has to represent + * + * Return: the number of pages needed to hold the bitmap. */ unsigned long __init bootmem_bootmap_pages(unsigned long pages) { @@ -121,7 +170,7 @@ static unsigned long __init init_bootmem_core(bootmem_data_t *bdata, * @startpfn: first pfn on the node * @endpfn: first pfn after the node * - * Returns the number of bytes needed to hold the bitmap for this node. + * Return: the number of bytes needed to hold the bitmap for this node. */ unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn) @@ -134,7 +183,7 @@ unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn, * @start: pfn where the bitmap is to be placed * @pages: number of available physical pages * - * Returns the number of bytes needed to hold the bitmap. + * Return: the number of bytes needed to hold the bitmap. */ unsigned long __init init_bootmem(unsigned long start, unsigned long pages) { @@ -143,15 +192,6 @@ unsigned long __init init_bootmem(unsigned long start, unsigned long pages) return init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages); } -/* - * free_bootmem_late - free bootmem pages directly to page allocator - * @addr: starting physical address of the range - * @size: size of the range in bytes - * - * This is only useful when the bootmem allocator has already been torn - * down, but we are still initializing the system. Pages are given directly - * to the page allocator, no bootmem metadata is updated because it is gone. - */ void __init free_bootmem_late(unsigned long physaddr, unsigned long size) { unsigned long cursor, end; @@ -264,11 +304,6 @@ void __init reset_all_zones_managed_pages(void) reset_managed_pages_done = 1; } -/** - * free_all_bootmem - release free pages to the buddy allocator - * - * Returns the number of pages actually released. - */ unsigned long __init free_all_bootmem(void) { unsigned long total_pages = 0; @@ -385,16 +420,6 @@ static int __init mark_bootmem(unsigned long start, unsigned long end, BUG(); } -/** - * free_bootmem_node - mark a page range as usable - * @pgdat: node the range resides on - * @physaddr: starting address of the range - * @size: size of the range in bytes - * - * Partial pages will be considered reserved and left as they are. - * - * The range must reside completely on the specified node. - */ void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr, unsigned long size) { @@ -408,15 +433,6 @@ void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr, mark_bootmem_node(pgdat->bdata, start, end, 0, 0); } -/** - * free_bootmem - mark a page range as usable - * @physaddr: starting physical address of the range - * @size: size of the range in bytes - * - * Partial pages will be considered reserved and left as they are. - * - * The range must be contiguous but may span node boundaries. - */ void __init free_bootmem(unsigned long physaddr, unsigned long size) { unsigned long start, end; @@ -439,6 +455,8 @@ void __init free_bootmem(unsigned long physaddr, unsigned long size) * Partial pages will be reserved. * * The range must reside completely on the specified node. + * + * Return: 0 on success, -errno on failure. */ int __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr, unsigned long size, int flags) @@ -460,6 +478,8 @@ int __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr, * Partial pages will be reserved. * * The range must be contiguous but may span node boundaries. + * + * Return: 0 on success, -errno on failure. */ int __init reserve_bootmem(unsigned long addr, unsigned long size, int flags) @@ -646,19 +666,6 @@ restart: return NULL; } -/** - * __alloc_bootmem_nopanic - allocate boot memory without panicking - * @size: size of the request in bytes - * @align: alignment of the region - * @goal: preferred starting address of the region - * - * The goal is dropped if it can not be satisfied and the allocation will - * fall back to memory below @goal. - * - * Allocation may happen on any node in the system. - * - * Returns NULL on failure. - */ void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align, unsigned long goal) { @@ -682,19 +689,6 @@ static void * __init ___alloc_bootmem(unsigned long size, unsigned long align, return NULL; } -/** - * __alloc_bootmem - allocate boot memory - * @size: size of the request in bytes - * @align: alignment of the region - * @goal: preferred starting address of the region - * - * The goal is dropped if it can not be satisfied and the allocation will - * fall back to memory below @goal. - * - * Allocation may happen on any node in the system. - * - * The function panics if the request can not be satisfied. - */ void * __init __alloc_bootmem(unsigned long size, unsigned long align, unsigned long goal) { @@ -754,21 +748,6 @@ void * __init ___alloc_bootmem_node(pg_data_t *pgdat, unsigned long size, return NULL; } -/** - * __alloc_bootmem_node - allocate boot memory from a specific node - * @pgdat: node to allocate from - * @size: size of the request in bytes - * @align: alignment of the region - * @goal: preferred starting address of the region - * - * The goal is dropped if it can not be satisfied and the allocation will - * fall back to memory below @goal. - * - * Allocation may fall back to any node in the system if the specified node - * can not hold the requested memory. - * - * The function panics if the request can not be satisfied. - */ void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal) { @@ -807,19 +786,6 @@ void * __init __alloc_bootmem_node_high(pg_data_t *pgdat, unsigned long size, } -/** - * __alloc_bootmem_low - allocate low boot memory - * @size: size of the request in bytes - * @align: alignment of the region - * @goal: preferred starting address of the region - * - * The goal is dropped if it can not be satisfied and the allocation will - * fall back to memory below @goal. - * - * Allocation may happen on any node in the system. - * - * The function panics if the request can not be satisfied. - */ void * __init __alloc_bootmem_low(unsigned long size, unsigned long align, unsigned long goal) { @@ -834,21 +800,6 @@ void * __init __alloc_bootmem_low_nopanic(unsigned long size, ARCH_LOW_ADDRESS_LIMIT); } -/** - * __alloc_bootmem_low_node - allocate low boot memory from a specific node - * @pgdat: node to allocate from - * @size: size of the request in bytes - * @align: alignment of the region - * @goal: preferred starting address of the region - * - * The goal is dropped if it can not be satisfied and the allocation will - * fall back to memory below @goal. - * - * Allocation may fall back to any node in the system if the specified node - * can not hold the requested memory. - * - * The function panics if the request can not be satisfied. - */ void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal) { |