L4Re – L4 Runtime Environment
L4Re::Dataspace Class Reference

Interface for memory-like objects. More...

+ Inheritance diagram for L4Re::Dataspace:
+ Collaboration diagram for L4Re::Dataspace:

Data Structures

struct  F
 Dataspace flags definitions. More...
 
struct  Stats
 Information about the dataspace. More...
 

Public Member Functions

long map (Offset offset, Flags flags, Map_addr local_addr, Map_addr min_addr, Map_addr max_addr) const noexcept
 Request a flex-page mapping from the dataspace. More...
 
long map_region (Offset offset, Flags flags, Map_addr min_addr, Map_addr max_addr) const noexcept
 Map a part of a dataspace into a local memory area. More...
 
long clear (Offset offset, Size size)
 Clear parts of a dataspace. More...
 
long allocate (Offset offset, Size size)
 Allocate a range in the dataspace. More...
 
long copy_in (Offset dst_offs, L4::Ipc::Cap< Dataspace > src, Offset src_offs, Size size)
 Copy contents from another dataspace. More...
 
Size size () const noexcept
 Get size of a dataspace. More...
 
Flags flags () const noexcept
 Get flags of the dataspace. More...
 
long info (Stats *stats)
 Get information on the dataspace. More...
 
- 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. More...
 

Additional Inherited Members

- Protected Types inherited from L4::Kobject_t< Dataspace, L4::Kobject, L4RE_PROTO_DATASPACE, L4::Type_info::Demand_t< 1 > >
typedef Dataspace Class
 The target interface type (inheriting from Kobject_t)
 
typedef Typeid::Iface< PROTO, Dataspace > __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< Dataspace, L4::Kobject, L4RE_PROTO_DATASPACE, L4::Type_info::Demand_t< 1 > >
L4::Cap< Classc () const noexcept
 Get the capability to ourselves.
 
- Protected Member Functions inherited from L4::Kobject
l4_cap_idx_t cap () const noexcept
 Return capability selector. More...
 
- Static Protected Member Functions inherited from L4::Kobject_t< Dataspace, L4::Kobject, L4RE_PROTO_DATASPACE, L4::Type_info::Demand_t< 1 > >
static void __check_protocols__ () noexcept
 Helper to check for protocol conflicts.
 

Detailed Description

Interface for memory-like objects.

Dataspaces are a central abstraction provided by L4Re. A dataspace is an abstraction for any thing that is available via usual memory access instructions. A dataspace can be a file, as well as the memory-mapped registers of a device, or anonymous memory, such as a heap.

The dataspace interface defines a set of methods that allow any kind of dataspace to be attached (mapped) to the virtual address space of an L4 task and then be accessed via memory-access instructions. The L4Re::Rm interface can be used to attach a dataspace to a virtual address space of a task paged by a certain instance of a region map.

Include File
#include <l4/re/dataspace>
Dataspace interface.
Examples
examples/libs/l4re/c++/mem_alloc/ma+rm.cc, examples/libs/l4re/c++/shared_ds/ds_clnt.cc, and examples/libs/l4re/c++/shared_ds/ds_srv.cc.

Definition at line 60 of file dataspace.

Member Function Documentation

◆ allocate()

long L4Re::Dataspace::allocate ( Offset  offset,
Size  size 
)

Allocate a range in the dataspace.

Parameters
offsetOffset in the dataspace, in bytes.
sizeSize of the range, in bytes.
Return values
L4_EOKSuccess
-L4_ERANGEGiven range is outside the dataspace. (A dataspace provider may also silently ignore areas outside the dataspace.)
-L4_ENOMEMNot enough memory available.
<0IPC errors

On success, at least the given range is guaranteed to be allocated. The dataspace manager may also allocate more memory due to page granularity.

The memory is allocated with the same rights as the dataspace capability.

◆ clear()

long L4Re::Dataspace::clear ( Offset  offset,
Size  size 
)

Clear parts of a dataspace.

Parameters
offsetOffset within dataspace (in bytes).
sizeSize of region to clear (in bytes).
Return values
>=0Success.
-L4_ERANGEGiven range is outside the dataspace. (A dataspace provider may also silently ignore areas outside the dataspace.)
-L4_EACCESSDataspace is read-only.
<0IPC errors

Zeroes out the memory. Depending on the type of memory the memory could also be deallocated and replaced by a shared zero-page.

◆ copy_in()

long L4Re::Dataspace::copy_in ( Offset  dst_offs,
L4::Ipc::Cap< Dataspace src,
Offset  src_offs,
Size  size 
)

Copy contents from another dataspace.

Parameters
dst_offsOffset in destination dataspace.
srcSource dataspace to copy from.
src_offsOffset in the source dataspace.
sizeSize to copy (in bytes).
Return values
L4_EOKSuccess
-L4_EACCESSDestination dataspace not writable.
-L4_EINVALInvalid parameter supplied.
<0IPC errors

The copy operation may use copy-on-write mechanisms. The operation may also fail if both dataspaces are not from the same dataspace manager or the dataspace managers do not cooperate.

◆ flags()

Dataspace::Flags L4Re::Dataspace::flags ( ) const
noexcept

Get flags of the dataspace.

Return values
>=0Flags of the dataspace
<0IPC errors
See also
L4Re::Dataspace::F::Flags

Definition at line 119 of file dataspace_impl.h.

Referenced by L4vbus::Vbus::assign_dma_domain().

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◆ info()

long L4Re::Dataspace::info ( Stats stats)

Get information on the dataspace.

Parameters
[out]statsDataspace information
Return values
0Success
<0IPC errors

◆ map()

long L4Re::Dataspace::map ( Dataspace::Offset  offset,
Dataspace::Flags  flags,
Dataspace::Map_addr  local_addr,
Dataspace::Map_addr  min_addr,
Dataspace::Map_addr  max_addr 
) const
noexcept

Request a flex-page mapping from the dataspace.

Parameters
offsetOffset to start within dataspace
flagsDataspace flags, see L4Re::Dataspace::F::Flags.
local_addrLocal address to map to.
min_addrDefines start of receive window. (Rounded down to page size.)
max_addrDefines end of receive window. (Rounded up to page size.)
Return values
L4_EOKSuccess
-L4_ERANGEInvalid offset.
-L4_EPERMInsufficient permission to map with requested rights.
<0IPC errors

The map call will attempt to map the largest possible flexpage that covers the given local address and still fits into the region defined by min_addr and max_addr. If the given region is invalid or does not overlap the local address, the smallest valid page size is used.

Definition at line 94 of file dataspace_impl.h.

References L4_LOG2_PAGESIZE.

◆ map_region()

long L4Re::Dataspace::map_region ( Dataspace::Offset  offset,
Dataspace::Flags  flags,
Dataspace::Map_addr  min_addr,
Dataspace::Map_addr  max_addr 
) const
noexcept

Map a part of a dataspace into a local memory area.

Parameters
offsetOffset to start within dataspace.
flagsDataspace flags, see L4Re::Dataspace::F::Flags.
min_addr(Inclusive) start of the receive area.
max_addr(Exclusive) end of receive area.
Return values
L4_EOKSuccess
-L4_ERANGEInvalid offset or receive area larger than the dataspace.
-L4_EPERMInsufficient permission to map with requested rights.
<0IPC errors

This is a convenience function which maps flex-pages consecutively into the given memory area in the local task. The area is expected to be filled completely. If the dataspace is not large enough to provide the mappings for the entire size of the area, then an error is returned. Mappings may or may not have been already established at that point.

offset and min_addr are rounded down to the next L4_PAGESIZE boundary when necessary. max_addr is rounded up to the page boundary. If the resulting maximum address is less or equal than the minimum address, then the function is a noop.

Definition at line 55 of file dataspace_impl.h.

References L4_LOG2_PAGESIZE, L4_UNLIKELY, L4::round_order(), and L4::trunc_order().

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◆ size()

Dataspace::Size L4Re::Dataspace::size ( ) const
noexcept

Get size of a dataspace.

Returns
Size of the dataspace in bytes.
Examples
examples/libs/l4re/c++/shared_ds/ds_clnt.cc.

Definition at line 109 of file dataspace_impl.h.


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