memory_object_data_supply

Function - Provide kernel with data previously requested by the kernel's Memory Management facility.

SYNOPSIS

kern_return_t   memory_object_data_supply
                (mem_object_control_port_t       memory_control,
                 vm_offset_t                             offset,
                 pointer_t                                 data,
                 mach_msg_type_number_t              data_count,
                 boolean_t                           deallocate,
                 vm_prot_t                           lock_value,
                 boolean_t                             precious,
                 mach_port_t                         reply_port);

PARAMETERS

memory_control

[in memory-cache-control send right] The memory cache control port to be used by the memory manager for cache management requests. This port is provided by the kernel in a memory_object_init or memory_object_create call.

offset

[in scalar] The offset within the memory object, in bytes.

data

[pointer to page aligned in array of bytes] The address of the data being provided to the kernel.

data_count

[in scalar] The amount of data to be provided. The number must be an integral number of memory object pages.

deallocate

[in scalar] If TRUE, the pages to be copied (starting at data) will be deallocated from the memory manager's address space as a result of being copied into the message, allowing the pages to be moved into the kernel instead of being physically copied.

lock_value

[in scalar] One or more forms of access not permitted for the specified data. Valid values are:

VM_PROT_NONE

Prohibits no access (that is, all forms of access are permitted).

VM_PROT_READ

Prohibits read access.

VM_PROT_WRITE

Prohibits write access.

VM_PROT_EXECUTE

Prohibits execute access.

VM_PROT_ALL

Prohibits all forms of access.

precious

[in scalar] If TRUE, the pages being supplied are "precious," that is, the memory manager is not (necessarily) retaining its own copy. These pages must be returned to the manager when evicted from memory, even if not modified.

reply_port

[in reply receive (to be converted to send) right] A port to which the kernel should send a memory_object_supply_completed to indicate the status of the accepted data. MACH_PORT_NULL is allowed. The reply message indicates which pages have been accepted.

DESCRIPTION

The memory_object_data_supply function supplies the kernel with a range of data for the specified memory object. A memory manager can only provide data that was requested by a memory_object_data_request call from the kernel.

NOTES

The kernel accepts only integral numbers of pages. It discards any partial pages without notification.

CAUTIONS

A memory manager must be careful that it not attempt to provide data that has not been explicitly requested. In particular, a memory manager must ensure that it does not provide writable data again before it receives back modifications from the kernel. This may require that the memory manager remember which pages it has provided, or that it exercise other cache control functions (via memory_object_lock_request) before proceeding. The kernel prohibits the overwriting of live data pages and will not accept pages it has not requested.

RETURN VALUES

Only generic errors apply.

RELATED INFORMATION

Functions: memory_object_data_error, memory_object_data_request, memory_object_data_unavailable, memory_object_lock_request, memory_object_supply_completed.