L4Re::Mem_alloc Class Reference

Memory allocation interface. More...

#include <mem_alloc>

Inheritance diagram for L4Re::Mem_alloc:

Collaboration diagram for L4Re::Mem_alloc:

Public Types
enum	Mem_alloc_flags { Continuous = 0x01 , Pinned = 0x02 , Super_pages = 0x04 }
	Flags for the allocator. More...

Public Member Functions
long	alloc (long size, L4::Cap< Dataspace > mem, unsigned long flags=0, unsigned long align=0) const noexcept
	Allocate anonymous memory.
Public Member Functions inherited from L4::Factory
S	create (Cap< void > target, long obj, l4_utcb_t *utcb=l4_utcb()) noexcept
	Generic create call to the factory.
template<typename OBJ >
S	create (Cap< OBJ > target, l4_utcb_t *utcb=l4_utcb()) noexcept
	Create call for typed capabilities.
l4_msgtag_t	create_task (Cap< Task > const &target_cap, l4_fpage_t const &utcb_area, l4_utcb_t *utcb=l4_utcb()) noexcept
	Create a new task.
l4_msgtag_t	create_factory (Cap< Factory > const &target_cap, unsigned long limit, l4_utcb_t *utcb=l4_utcb()) noexcept
	Create a new factory.
l4_msgtag_t	create_gate (Cap< void > const &target_cap, Cap< Thread > const &thread_cap, l4_umword_t label, l4_utcb_t *utcb=l4_utcb()) noexcept
	Create a new IPC gate.
Public Member Functions inherited from L4::Kobject
l4_msgtag_t	dec_refcnt (l4_mword_t diff, l4_utcb_t *utcb=l4_utcb())
	Decrement the in kernel reference counter for the object.

Additional Inherited Members
Protected Types inherited from L4::Kobject_t< Mem_alloc, L4::Factory, L4::PROTO_EMPTY >
typedef Mem_alloc	Class
	The target interface type (inheriting from Kobject_t)
typedef Typeid::Iface< PROTO, Mem_alloc >	__Iface
	The interface description for the derived class.
typedef Typeid::Merge_list< Typeid::Iface_list< __Iface >, typename Base::__Iface_list >	__Iface_list
	The list of all RPC interfaces provided directly or through inheritance.
Protected Types inherited from L4::Kobject_t< Factory, Kobject, L4_PROTO_FACTORY >
typedef Factory	Class
	The target interface type (inheriting from Kobject_t)
typedef Typeid::Iface< PROTO, Factory >	__Iface
	The interface description for the derived class.
typedef Typeid::Merge_list< Typeid::Iface_list< __Iface >, typename Base::__Iface_list >	__Iface_list
	The list of all RPC interfaces provided directly or through inheritance.
Protected Member Functions inherited from L4::Kobject_t< Mem_alloc, L4::Factory, L4::PROTO_EMPTY >
L4::Cap< Class >	c () const noexcept
	Get the capability to ourselves.
Protected Member Functions inherited from L4::Kobject_t< Factory, Kobject, L4_PROTO_FACTORY >
L4::Cap< Class >	c () const noexcept
	Get the capability to ourselves.
Protected Member Functions inherited from L4::Kobject
l4_cap_idx_t	cap () const noexcept
	Return capability selector.
Static Protected Member Functions inherited from L4::Kobject_t< Mem_alloc, L4::Factory, L4::PROTO_EMPTY >
static void	__check_protocols__ () noexcept
	Helper to check for protocol conflicts.
Static Protected Member Functions inherited from L4::Kobject_t< Factory, Kobject, L4_PROTO_FACTORY >
static void	__check_protocols__ () noexcept
	Helper to check for protocol conflicts.

Detailed Description

Memory allocation interface.

The memory-allocator API is the basic API to allocate memory from the L4Re subsystem. The memory is allocated in terms of dataspaces (see L4Re::Dataspace). The provided dataspaces have at least the property that data written to such a dataspace is available as long as the dataspace is not freed or the data is not overwritten. In particular, the memory backing a dataspace from an allocator need not be allocated instantly, but may be allocated lazily on demand.

A memory allocator can provide dataspaces with additional properties, such as physically contiguous memory, pre-allocated memory, or pinned memory. To request memory with an additional property the L4Re::Mem_alloc::alloc() method provides a flags parameter. If the concrete implementation of a memory allocator does not support or allow allocation of memory with a certain property, the allocation may be refused.

Definition at line 61 of file mem_alloc.

Member Enumeration Documentation

Mem_alloc_flags

enum L4Re::Mem_alloc::Mem_alloc_flags

Flags for the allocator.

They describe requested properties of the allocated memory. Support of these properties by the dataspace provider is optional.

Enumerator
Continuous	Allocate physically contiguous memory.
Pinned	Deprecated, use L4Re::Dma_space instead.
Super_pages	Allocate super pages.

Definition at line 71 of file mem_alloc.

Member Function Documentation

alloc()

long L4Re::Mem_alloc::alloc ( long  size, L4::Cap< Dataspace >  mem, unsigned long  flags = 0, unsigned long  align = 0  ) const

noexcept

Allocate anonymous memory.

Parameters

	size	Size in bytes to be requested. Allocation granularity is (super)pages, however, the allocator will store the byte-granular given size as the size of the dataspace and consecutively will use this byte-granular size for servicing the dataspace. Allocators may optionally also implement a maximum allocation strategy: if size is a negative value and flags set the Mem_alloc_flags::Continuous bit, the allocator tries to allocate as much memory as possible leaving an amount of at least -size bytes within the associated quota.
[out]	mem	Capability slot where the capability to the dataspace is received.
	flags	Special dataspace properties, see Mem_alloc_flags
	align	Log2 alignment of dataspace if supported by allocator, will be at least L4_PAGESHIFT, with Super_pages flag set at least L4_SUPERPAGESHIFT

Return values

0	Success
-L4_ERANGE	Given size not supported.
-L4_ENOMEM	Not enough memory available.
<0	IPC error

Definition at line 35 of file mem_alloc_impl.h.

References l4_error().

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The documentation for this class was generated from the following files:

• l4/re/mem_alloc
• l4/re/impl/mem_alloc_impl.h