Boot time memory management¶
Early system initialization cannot use “normal” memory management simply because it is not set up yet. But there is still need to allocate memory for various data structures, for instance for the physical page allocator.
A specialized allocator called memblock
performs the
boot time memory management. The architecture specific initialization
must set it up in setup_arch()
and tear it down in
mem_init()
functions.
Once the early memory management is available it offers a variety of functions and macros for memory allocations. The allocation request may be directed to the first (and probably the only) node or to a particular node in a NUMA system. There are API variants that panic when an allocation fails and those that don’t.
Memblock also offers a variety of APIs that control its own behaviour.
Memblock Overview¶
Memblock is a method of managing memory regions during the early boot period when the usual kernel memory allocators are not up and running.
Memblock views the system memory as collections of contiguous regions. There are several types of these collections:
memory
- describes the physical memory available to the kernel; this may differ from the actual physical memory installed in the system, for instance when the memory is restricted withmem=
command line parameterreserved
- describes the regions that were allocatedphysmap
- describes the actual physical memory regardless of the possible restrictions; thephysmap
type is only available on some architectures.
Each region is represented by struct memblock_region
that
defines the region extents, its attributes and NUMA node id on NUMA
systems. Every memory type is described by the struct
memblock_type
which contains an array of memory regions along with
the allocator metadata. The memory types are nicely wrapped with
struct memblock
. This structure is statically initialzed
at build time. The region arrays for the “memory” and “reserved”
types are initially sized to INIT_MEMBLOCK_REGIONS
and for the
“physmap” type to INIT_PHYSMEM_REGIONS
.
The memblock_allow_resize() enables automatic resizing of the region
arrays during addition of new regions. This feature should be used
with care so that memory allocated for the region array will not
overlap with areas that should be reserved, for example initrd.
The early architecture setup should tell memblock what the physical
memory layout is by using memblock_add()
or memblock_add_node()
functions. The first function does not assign the region to a NUMA
node and it is appropriate for UMA systems. Yet, it is possible to
use it on NUMA systems as well and assign the region to a NUMA node
later in the setup process using memblock_set_node()
. The
memblock_add_node()
performs such an assignment directly.
Once memblock is setup the memory can be allocated using one of the API variants:
- memblock_phys_alloc*() - these functions return the physical address of the allocated memory
- memblock_alloc*() - these functions return the virtual address of the allocated memory.
Note, that both API variants use implict assumptions about allowed
memory ranges and the fallback methods. Consult the documentation
of memblock_alloc_internal()
and memblock_alloc_range_nid()
functions for more elaborate description.
As the system boot progresses, the architecture specific mem_init() function frees all the memory to the buddy page allocator.
Unless an architecture enables CONFIG_ARCH_KEEP_MEMBLOCK
, the
memblock data structures will be discarded after the system
initialization completes.
Functions and structures¶
Here is the description of memblock data structures, functions and macros. Some of them are actually internal, but since they are documented it would be silly to omit them. Besides, reading the descriptions for the internal functions can help to understand what really happens under the hood.
-
enum
memblock_flags
¶ definition of memory region attributes
Constants
MEMBLOCK_NONE
- no special request
MEMBLOCK_HOTPLUG
- hotpluggable region
MEMBLOCK_MIRROR
- mirrored region
MEMBLOCK_NOMAP
- don’t add to kernel direct mapping
-
struct
memblock_region
¶ represents a memory region
Definition
struct memblock_region {
phys_addr_t base;
phys_addr_t size;
enum memblock_flags flags;
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP;
int nid;
#endif;
};
Members
base
- physical address of the region
size
- size of the region
flags
- memory region attributes
nid
- NUMA node id
-
struct
memblock_type
¶ collection of memory regions of certain type
Definition
struct memblock_type {
unsigned long cnt;
unsigned long max;
phys_addr_t total_size;
struct memblock_region *regions;
char *name;
};
Members
cnt
- number of regions
max
- size of the allocated array
total_size
- size of all regions
regions
- array of regions
name
- the memory type symbolic name
-
struct
memblock
¶ memblock allocator metadata
Definition
struct memblock {
bool bottom_up;
phys_addr_t current_limit;
struct memblock_type memory;
struct memblock_type reserved;
#ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP;
struct memblock_type physmem;
#endif;
};
Members
bottom_up
- is bottom up direction?
current_limit
- physical address of the current allocation limit
memory
- usabe memory regions
reserved
- reserved memory regions
physmem
- all physical memory
-
for_each_mem_range
(i, type_a, type_b, nid, flags, p_start, p_end, p_nid)¶ iterate through memblock areas from type_a and not included in type_b. Or just type_a if type_b is NULL.
Parameters
i
- u64 used as loop variable
type_a
- ptr to memblock_type to iterate
type_b
- ptr to memblock_type which excludes from the iteration
nid
- node selector,
NUMA_NO_NODE
for all nodes flags
- pick from blocks based on memory attributes
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
p_nid
- ptr to int for nid of the range, can be
NULL
-
for_each_mem_range_rev
(i, type_a, type_b, nid, flags, p_start, p_end, p_nid)¶ reverse iterate through memblock areas from type_a and not included in type_b. Or just type_a if type_b is NULL.
Parameters
i
- u64 used as loop variable
type_a
- ptr to memblock_type to iterate
type_b
- ptr to memblock_type which excludes from the iteration
nid
- node selector,
NUMA_NO_NODE
for all nodes flags
- pick from blocks based on memory attributes
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
p_nid
- ptr to int for nid of the range, can be
NULL
-
for_each_reserved_mem_region
(i, p_start, p_end)¶ iterate over all reserved memblock areas
Parameters
i
- u64 used as loop variable
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
Description
Walks over reserved areas of memblock. Available as soon as memblock is initialized.
-
for_each_mem_pfn_range
(i, nid, p_start, p_end, p_nid)¶ early memory pfn range iterator
Parameters
i
- an integer used as loop variable
nid
- node selector,
MAX_NUMNODES
for all nodes p_start
- ptr to ulong for start pfn of the range, can be
NULL
p_end
- ptr to ulong for end pfn of the range, can be
NULL
p_nid
- ptr to int for nid of the range, can be
NULL
Description
Walks over configured memory ranges.
-
for_each_free_mem_pfn_range_in_zone
(i, zone, p_start, p_end)¶ iterate through zone specific free memblock areas
Parameters
i
- u64 used as loop variable
zone
- zone in which all of the memory blocks reside
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
Description
Walks over free (memory && !reserved) areas of memblock in a specific zone. Available once memblock and an empty zone is initialized. The main assumption is that the zone start, end, and pgdat have been associated. This way we can use the zone to determine NUMA node, and if a given part of the memblock is valid for the zone.
-
for_each_free_mem_pfn_range_in_zone_from
(i, zone, p_start, p_end)¶ iterate through zone specific free memblock areas from a given point
Parameters
i
- u64 used as loop variable
zone
- zone in which all of the memory blocks reside
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
Description
Walks over free (memory && !reserved) areas of memblock in a specific zone, continuing from current position. Available as soon as memblock is initialized.
-
for_each_free_mem_range
(i, nid, flags, p_start, p_end, p_nid)¶ iterate through free memblock areas
Parameters
i
- u64 used as loop variable
nid
- node selector,
NUMA_NO_NODE
for all nodes flags
- pick from blocks based on memory attributes
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
p_nid
- ptr to int for nid of the range, can be
NULL
Description
Walks over free (memory && !reserved) areas of memblock. Available as soon as memblock is initialized.
-
for_each_free_mem_range_reverse
(i, nid, flags, p_start, p_end, p_nid)¶ rev-iterate through free memblock areas
Parameters
i
- u64 used as loop variable
nid
- node selector,
NUMA_NO_NODE
for all nodes flags
- pick from blocks based on memory attributes
p_start
- ptr to phys_addr_t for start address of the range, can be
NULL
p_end
- ptr to phys_addr_t for end address of the range, can be
NULL
p_nid
- ptr to int for nid of the range, can be
NULL
Description
Walks over free (memory && !reserved) areas of memblock in reverse order. Available as soon as memblock is initialized.
-
void
memblock_set_current_limit
(phys_addr_t limit)¶ Set the current allocation limit to allow limiting allocations to what is currently accessible during boot
Parameters
phys_addr_t limit
- New limit value (physical address)
-
unsigned long
memblock_region_memory_base_pfn
(const struct memblock_region * reg)¶ get the lowest pfn of the memory region
Parameters
const struct memblock_region * reg
- memblock_region structure
Return
the lowest pfn intersecting with the memory region
-
unsigned long
memblock_region_memory_end_pfn
(const struct memblock_region * reg)¶ get the end pfn of the memory region
Parameters
const struct memblock_region * reg
- memblock_region structure
Return
the end_pfn of the reserved region
-
unsigned long
memblock_region_reserved_base_pfn
(const struct memblock_region * reg)¶ get the lowest pfn of the reserved region
Parameters
const struct memblock_region * reg
- memblock_region structure
Return
the lowest pfn intersecting with the reserved region
-
unsigned long
memblock_region_reserved_end_pfn
(const struct memblock_region * reg)¶ get the end pfn of the reserved region
Parameters
const struct memblock_region * reg
- memblock_region structure
Return
the end_pfn of the reserved region
-
phys_addr_t __init_memblock
__memblock_find_range_bottom_up
(phys_addr_t start, phys_addr_t end, phys_addr_t size, phys_addr_t align, int nid, enum memblock_flags flags)¶ find free area utility in bottom-up
Parameters
phys_addr_t start
- start of candidate range
phys_addr_t end
- end of candidate range, can be
MEMBLOCK_ALLOC_ANYWHERE
orMEMBLOCK_ALLOC_ACCESSIBLE
phys_addr_t size
- size of free area to find
phys_addr_t align
- alignment of free area to find
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node enum memblock_flags flags
- pick from blocks based on memory attributes
Description
Utility called from memblock_find_in_range_node()
, find free area bottom-up.
Return
Found address on success, 0 on failure.
-
phys_addr_t __init_memblock
__memblock_find_range_top_down
(phys_addr_t start, phys_addr_t end, phys_addr_t size, phys_addr_t align, int nid, enum memblock_flags flags)¶ find free area utility, in top-down
Parameters
phys_addr_t start
- start of candidate range
phys_addr_t end
- end of candidate range, can be
MEMBLOCK_ALLOC_ANYWHERE
orMEMBLOCK_ALLOC_ACCESSIBLE
phys_addr_t size
- size of free area to find
phys_addr_t align
- alignment of free area to find
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node enum memblock_flags flags
- pick from blocks based on memory attributes
Description
Utility called from memblock_find_in_range_node()
, find free area top-down.
Return
Found address on success, 0 on failure.
-
phys_addr_t __init_memblock
memblock_find_in_range_node
(phys_addr_t size, phys_addr_t align, phys_addr_t start, phys_addr_t end, int nid, enum memblock_flags flags)¶ find free area in given range and node
Parameters
phys_addr_t size
- size of free area to find
phys_addr_t align
- alignment of free area to find
phys_addr_t start
- start of candidate range
phys_addr_t end
- end of candidate range, can be
MEMBLOCK_ALLOC_ANYWHERE
orMEMBLOCK_ALLOC_ACCESSIBLE
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node enum memblock_flags flags
- pick from blocks based on memory attributes
Description
Find size free area aligned to align in the specified range and node.
When allocation direction is bottom-up, the start should be greater than the end of the kernel image. Otherwise, it will be trimmed. The reason is that we want the bottom-up allocation just near the kernel image so it is highly likely that the allocated memory and the kernel will reside in the same node.
If bottom-up allocation failed, will try to allocate memory top-down.
Return
Found address on success, 0 on failure.
-
phys_addr_t __init_memblock
memblock_find_in_range
(phys_addr_t start, phys_addr_t end, phys_addr_t size, phys_addr_t align)¶ find free area in given range
Parameters
phys_addr_t start
- start of candidate range
phys_addr_t end
- end of candidate range, can be
MEMBLOCK_ALLOC_ANYWHERE
orMEMBLOCK_ALLOC_ACCESSIBLE
phys_addr_t size
- size of free area to find
phys_addr_t align
- alignment of free area to find
Description
Find size free area aligned to align in the specified range.
Return
Found address on success, 0 on failure.
-
void
memblock_discard
(void)¶ discard memory and reserved arrays if they were allocated
Parameters
void
- no arguments
-
int __init_memblock
memblock_double_array
(struct memblock_type * type, phys_addr_t new_area_start, phys_addr_t new_area_size)¶ double the size of the memblock regions array
Parameters
struct memblock_type * type
- memblock type of the regions array being doubled
phys_addr_t new_area_start
- starting address of memory range to avoid overlap with
phys_addr_t new_area_size
- size of memory range to avoid overlap with
Description
Double the size of the type regions array. If memblock is being used to allocate memory for a new reserved regions array and there is a previously allocated memory range [new_area_start, new_area_start + new_area_size] waiting to be reserved, ensure the memory used by the new array does not overlap.
Return
0 on success, -1 on failure.
-
void __init_memblock
memblock_merge_regions
(struct memblock_type * type)¶ merge neighboring compatible regions
Parameters
struct memblock_type * type
- memblock type to scan
Description
Scan type and merge neighboring compatible regions.
-
void __init_memblock
memblock_insert_region
(struct memblock_type * type, int idx, phys_addr_t base, phys_addr_t size, int nid, enum memblock_flags flags)¶ insert new memblock region
Parameters
struct memblock_type * type
- memblock type to insert into
int idx
- index for the insertion point
phys_addr_t base
- base address of the new region
phys_addr_t size
- size of the new region
int nid
- node id of the new region
enum memblock_flags flags
- flags of the new region
Description
Insert new memblock region [base, base + size) into type at idx. type must already have extra room to accommodate the new region.
-
int __init_memblock
memblock_add_range
(struct memblock_type * type, phys_addr_t base, phys_addr_t size, int nid, enum memblock_flags flags)¶ add new memblock region
Parameters
struct memblock_type * type
- memblock type to add new region into
phys_addr_t base
- base address of the new region
phys_addr_t size
- size of the new region
int nid
- nid of the new region
enum memblock_flags flags
- flags of the new region
Description
Add new memblock region [base, base + size) into type. The new region is allowed to overlap with existing ones - overlaps don’t affect already existing regions. type is guaranteed to be minimal (all neighbouring compatible regions are merged) after the addition.
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_add_node
(phys_addr_t base, phys_addr_t size, int nid)¶ add new memblock region within a NUMA node
Parameters
phys_addr_t base
- base address of the new region
phys_addr_t size
- size of the new region
int nid
- nid of the new region
Description
Add new memblock region [base, base + size) to the “memory”
type. See memblock_add_range()
description for mode details
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_add
(phys_addr_t base, phys_addr_t size)¶ add new memblock region
Parameters
phys_addr_t base
- base address of the new region
phys_addr_t size
- size of the new region
Description
Add new memblock region [base, base + size) to the “memory”
type. See memblock_add_range()
description for mode details
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_isolate_range
(struct memblock_type * type, phys_addr_t base, phys_addr_t size, int * start_rgn, int * end_rgn)¶ isolate given range into disjoint memblocks
Parameters
struct memblock_type * type
- memblock type to isolate range for
phys_addr_t base
- base of range to isolate
phys_addr_t size
- size of range to isolate
int * start_rgn
- out parameter for the start of isolated region
int * end_rgn
- out parameter for the end of isolated region
Description
Walk type and ensure that regions don’t cross the boundaries defined by [base, base + size). Crossing regions are split at the boundaries, which may create at most two more regions. The index of the first region inside the range is returned in *start_rgn and end in *end_rgn.
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_free
(phys_addr_t base, phys_addr_t size)¶ free boot memory block
Parameters
phys_addr_t base
- phys starting address of the boot memory block
phys_addr_t size
- size of the boot memory block in bytes
Description
Free boot memory block previously allocated by memblock_alloc_xx() API. The freeing memory will not be released to the buddy allocator.
-
int __init_memblock
memblock_setclr_flag
(phys_addr_t base, phys_addr_t size, int set, int flag)¶ set or clear flag for a memory region
Parameters
phys_addr_t base
- base address of the region
phys_addr_t size
- size of the region
int set
- set or clear the flag
int flag
- the flag to udpate
Description
This function isolates region [base, base + size), and sets/clears flag
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_mark_hotplug
(phys_addr_t base, phys_addr_t size)¶ Mark hotpluggable memory with flag MEMBLOCK_HOTPLUG.
Parameters
phys_addr_t base
- the base phys addr of the region
phys_addr_t size
- the size of the region
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_clear_hotplug
(phys_addr_t base, phys_addr_t size)¶ Clear flag MEMBLOCK_HOTPLUG for a specified region.
Parameters
phys_addr_t base
- the base phys addr of the region
phys_addr_t size
- the size of the region
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_mark_mirror
(phys_addr_t base, phys_addr_t size)¶ Mark mirrored memory with flag MEMBLOCK_MIRROR.
Parameters
phys_addr_t base
- the base phys addr of the region
phys_addr_t size
- the size of the region
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_mark_nomap
(phys_addr_t base, phys_addr_t size)¶ Mark a memory region with flag MEMBLOCK_NOMAP.
Parameters
phys_addr_t base
- the base phys addr of the region
phys_addr_t size
- the size of the region
Return
0 on success, -errno on failure.
-
int __init_memblock
memblock_clear_nomap
(phys_addr_t base, phys_addr_t size)¶ Clear flag MEMBLOCK_NOMAP for a specified region.
Parameters
phys_addr_t base
- the base phys addr of the region
phys_addr_t size
- the size of the region
Return
0 on success, -errno on failure.
-
void __init_memblock
__next_reserved_mem_region
(u64 * idx, phys_addr_t * out_start, phys_addr_t * out_end)¶ next function for for_each_reserved_region()
Parameters
u64 * idx
- pointer to u64 loop variable
phys_addr_t * out_start
- ptr to phys_addr_t for start address of the region, can be
NULL
phys_addr_t * out_end
- ptr to phys_addr_t for end address of the region, can be
NULL
Description
Iterate over all reserved memory regions.
-
void __init_memblock
__next_mem_range
(u64 * idx, int nid, enum memblock_flags flags, struct memblock_type * type_a, struct memblock_type * type_b, phys_addr_t * out_start, phys_addr_t * out_end, int * out_nid)¶ next function for
for_each_free_mem_range()
etc.
Parameters
u64 * idx
- pointer to u64 loop variable
int nid
- node selector,
NUMA_NO_NODE
for all nodes enum memblock_flags flags
- pick from blocks based on memory attributes
struct memblock_type * type_a
- pointer to memblock_type from where the range is taken
struct memblock_type * type_b
- pointer to memblock_type which excludes memory from being taken
phys_addr_t * out_start
- ptr to phys_addr_t for start address of the range, can be
NULL
phys_addr_t * out_end
- ptr to phys_addr_t for end address of the range, can be
NULL
int * out_nid
- ptr to int for nid of the range, can be
NULL
Description
Find the first area from *idx which matches nid, fill the out parameters, and update *idx for the next iteration. The lower 32bit of *idx contains index into type_a and the upper 32bit indexes the areas before each region in type_b. For example, if type_b regions look like the following,
0:[0-16), 1:[32-48), 2:[128-130)
The upper 32bit indexes the following regions.
0:[0-0), 1:[16-32), 2:[48-128), 3:[130-MAX)
As both region arrays are sorted, the function advances the two indices in lockstep and returns each intersection.
-
void __init_memblock
__next_mem_range_rev
(u64 * idx, int nid, enum memblock_flags flags, struct memblock_type * type_a, struct memblock_type * type_b, phys_addr_t * out_start, phys_addr_t * out_end, int * out_nid)¶ generic next function for for_each_*_range_rev()
Parameters
u64 * idx
- pointer to u64 loop variable
int nid
- node selector,
NUMA_NO_NODE
for all nodes enum memblock_flags flags
- pick from blocks based on memory attributes
struct memblock_type * type_a
- pointer to memblock_type from where the range is taken
struct memblock_type * type_b
- pointer to memblock_type which excludes memory from being taken
phys_addr_t * out_start
- ptr to phys_addr_t for start address of the range, can be
NULL
phys_addr_t * out_end
- ptr to phys_addr_t for end address of the range, can be
NULL
int * out_nid
- ptr to int for nid of the range, can be
NULL
Description
Finds the next range from type_a which is not marked as unsuitable in type_b.
Reverse of __next_mem_range()
.
-
int __init_memblock
memblock_set_node
(phys_addr_t base, phys_addr_t size, struct memblock_type * type, int nid)¶ set node ID on memblock regions
Parameters
phys_addr_t base
- base of area to set node ID for
phys_addr_t size
- size of area to set node ID for
struct memblock_type * type
- memblock type to set node ID for
int nid
- node ID to set
Description
Set the nid of memblock type regions in [base, base + size) to nid. Regions which cross the area boundaries are split as necessary.
Return
0 on success, -errno on failure.
-
void __init_memblock
__next_mem_pfn_range_in_zone
(u64 * idx, struct zone * zone, unsigned long * out_spfn, unsigned long * out_epfn)¶ iterator for for_each_*_range_in_zone()
Parameters
u64 * idx
- pointer to u64 loop variable
struct zone * zone
- zone in which all of the memory blocks reside
unsigned long * out_spfn
- ptr to ulong for start pfn of the range, can be
NULL
unsigned long * out_epfn
- ptr to ulong for end pfn of the range, can be
NULL
Description
This function is meant to be a zone/pfn specific wrapper for the for_each_mem_range type iterators. Specifically they are used in the deferred memory init routines and as such we were duplicating much of this logic throughout the code. So instead of having it in multiple locations it seemed like it would make more sense to centralize this to one new iterator that does everything they need.
-
phys_addr_t
memblock_alloc_range_nid
(phys_addr_t size, phys_addr_t align, phys_addr_t start, phys_addr_t end, int nid, bool exact_nid)¶ allocate boot memory block
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t start
- the lower bound of the memory region to allocate (phys address)
phys_addr_t end
- the upper bound of the memory region to allocate (phys address)
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node bool exact_nid
- control the allocation fall back to other nodes
Description
The allocation is performed from memory region limited by
memblock.current_limit if end == MEMBLOCK_ALLOC_ACCESSIBLE
.
If the specified node can not hold the requested memory and exact_nid is false, the allocation falls back to any node in the system.
For systems with memory mirroring, the allocation is attempted first from the regions with mirroring enabled and then retried from any memory region.
In addition, function sets the min_count to 0 using kmemleak_alloc_phys for allocated boot memory block, so that it is never reported as leaks.
Return
Physical address of allocated memory block on success, 0
on failure.
-
phys_addr_t
memblock_phys_alloc_range
(phys_addr_t size, phys_addr_t align, phys_addr_t start, phys_addr_t end)¶ allocate a memory block inside specified range
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t start
- the lower bound of the memory region to allocate (physical address)
phys_addr_t end
- the upper bound of the memory region to allocate (physical address)
Description
Allocate size bytes in the between start and end.
Return
physical address of the allocated memory block on success,
0
on failure.
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phys_addr_t
memblock_phys_alloc_try_nid
(phys_addr_t size, phys_addr_t align, int nid)¶ allocate a memory block from specified MUMA node
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node
Description
Allocates memory block from the specified NUMA node. If the node has no available memory, attempts to allocated from any node in the system.
Return
physical address of the allocated memory block on success,
0
on failure.
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void *
memblock_alloc_internal
(phys_addr_t size, phys_addr_t align, phys_addr_t min_addr, phys_addr_t max_addr, int nid, bool exact_nid)¶ allocate boot memory block
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t min_addr
- the lower bound of the memory region to allocate (phys address)
phys_addr_t max_addr
- the upper bound of the memory region to allocate (phys address)
int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node bool exact_nid
- control the allocation fall back to other nodes
Description
Allocates memory block using memblock_alloc_range_nid()
and
converts the returned physical address to virtual.
The min_addr limit is dropped if it can not be satisfied and the allocation
will fall back to memory below min_addr. Other constraints, such
as node and mirrored memory will be handled again in
memblock_alloc_range_nid()
.
Return
Virtual address of allocated memory block on success, NULL on failure.
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void *
memblock_alloc_exact_nid_raw
(phys_addr_t size, phys_addr_t align, phys_addr_t min_addr, phys_addr_t max_addr, int nid)¶ allocate boot memory block on the exact node without zeroing memory
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t min_addr
- the lower bound of the memory region from where the allocation is preferred (phys address)
phys_addr_t max_addr
- the upper bound of the memory region from where the allocation
is preferred (phys address), or
MEMBLOCK_ALLOC_ACCESSIBLE
to allocate only from memory limited by memblock.current_limit value int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node
Description
Public function, provides additional debug information (including caller info), if enabled. Does not zero allocated memory.
Return
Virtual address of allocated memory block on success, NULL on failure.
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void *
memblock_alloc_try_nid_raw
(phys_addr_t size, phys_addr_t align, phys_addr_t min_addr, phys_addr_t max_addr, int nid)¶ allocate boot memory block without zeroing memory and without panicking
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t min_addr
- the lower bound of the memory region from where the allocation is preferred (phys address)
phys_addr_t max_addr
- the upper bound of the memory region from where the allocation
is preferred (phys address), or
MEMBLOCK_ALLOC_ACCESSIBLE
to allocate only from memory limited by memblock.current_limit value int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node
Description
Public function, provides additional debug information (including caller info), if enabled. Does not zero allocated memory, does not panic if request cannot be satisfied.
Return
Virtual address of allocated memory block on success, NULL on failure.
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void *
memblock_alloc_try_nid
(phys_addr_t size, phys_addr_t align, phys_addr_t min_addr, phys_addr_t max_addr, int nid)¶ allocate boot memory block
Parameters
phys_addr_t size
- size of memory block to be allocated in bytes
phys_addr_t align
- alignment of the region and block’s size
phys_addr_t min_addr
- the lower bound of the memory region from where the allocation is preferred (phys address)
phys_addr_t max_addr
- the upper bound of the memory region from where the allocation
is preferred (phys address), or
MEMBLOCK_ALLOC_ACCESSIBLE
to allocate only from memory limited by memblock.current_limit value int nid
- nid of the free area to find,
NUMA_NO_NODE
for any node
Description
Public function, provides additional debug information (including caller info), if enabled. This function zeroes the allocated memory.
Return
Virtual address of allocated memory block on success, NULL on failure.
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void
__memblock_free_late
(phys_addr_t base, phys_addr_t size)¶ free pages directly to buddy allocator
Parameters
phys_addr_t base
- phys starting address of the boot memory block
phys_addr_t size
- size of the boot memory block in bytes
Description
This is only useful when the memblock allocator has already been torn down, but we are still initializing the system. Pages are released directly to the buddy allocator.
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bool __init_memblock
memblock_is_region_memory
(phys_addr_t base, phys_addr_t size)¶ check if a region is a subset of memory
Parameters
phys_addr_t base
- base of region to check
phys_addr_t size
- size of region to check
Description
Check if the region [base, base + size) is a subset of a memory block.
Return
0 if false, non-zero if true
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bool __init_memblock
memblock_is_region_reserved
(phys_addr_t base, phys_addr_t size)¶ check if a region intersects reserved memory
Parameters
phys_addr_t base
- base of region to check
phys_addr_t size
- size of region to check
Description
Check if the region [base, base + size) intersects a reserved memory block.
Return
True if they intersect, false if not.
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unsigned long
memblock_free_all
(void)¶ release free pages to the buddy allocator
Parameters
void
- no arguments
Return
the number of pages actually released.