vm_att Kernel Service

Purpose

Maps a specified virtual memory object to a region in the current address space.

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/vmuser.h>

caddr_t vm_att ( vmhandle, offset) vmhandle_t vmhandle; caddr_t offset;

Item	Description
vmhandle	Specifies the handle for the virtual memory object to be mapped.
offset	Specifies the offset in the virtual memory object and region.

The vm_att kernel service performs the following tasks:

Selects an unallocated region in the current address space and allocates it.
Maps the virtual memory object specified by the vmhandle parameter with the access permission specified in the handle.
Constructs the address in the current address space corresponding to the offset in the virtual memory object and region.

The vm_att kernel service assumes an address space model of fixed-size virtual memory objects and address space regions.

Attention: If there are no more free regions, this call cannot complete and calls the panic kernel service.

The vm_att kernel service can be called from either the process or interrupt environment.

The vm_att kernel service returns the address that corresponds to the offset parameter in the address space.