1<h2>vm_remap</h2> 2<hr> 3<p> 4<strong>Function</strong> - Map memory objects in one task's address space to that of another task's. 5<h3>SYNOPSIS</h3> 6<pre> 7<strong>kern_return_t vm_remap</strong> 8 <strong>(mach_port_t</strong> <var>target_task</var>, 9 <strong>vm_address_t</strong> <var>target_address</var>, 10 <strong>vm_size_t</strong> <var>size</var>, 11 <strong>vm_address_t</strong> <var>mask</var>, 12 <strong>boolean_t</strong> <var>anywhere</var>, 13 <strong>mach_port_t</strong> <var>source_task</var>, 14 <strong>vm_address_t</strong> <var>source_address</var>, 15 <strong>boolean_t</strong> <var>copy</var>, 16 <strong>vm_prot_t</strong> <var>cur_protection</var>, 17 <strong>vm_prot_t</strong> <var>max_protection</var>, 18 <strong>vm_inherit_t</strong> <var>inheritance</var><strong>);</strong> 19</pre> 20<h3>PARAMETERS</h3> 21<dl> 22<dt> <var>target_task</var> 23<dd> 24[in task send right] 25The port for the task in whose address space the 26memory is to be mapped. 27 <p> 28<dt> <var>target_address</var> 29<dd> 30[pointer to in/out scalar] 31The starting address for the mapped memory 32in the target task. The mapped memory will start at the beginning of 33the page containing <var>target_address</var>. If there is not enough room 34following the address, the kernel does not map the memory. The kernel 35returns the starting address actually used for the mapped memory. 36 <p> 37<dt> <var>size</var> 38<dd> 39[in scalar] 40The number of bytes to map. The kernel rounds this number 41up to an integral number of virtual pages. 42<p> 43<dt> <var>mask</var> 44<dd> 45[in scalar] 46Alignment restrictions for starting address. Bits turned on in 47the mask will not be turned on in the starting address. 48<p> 49<dt> <var>anywhere</var> 50<dd> 51[in scalar] 52Placement indicator. 53 The valid values are: 54<dl> 55<p> 56 <dt> <strong>TRUE</strong> 57<dd> 58The kernel allocates the region in the next unused space that 59is sufficient within the address space. The kernel returns the 60starting address actually used in <var>address</var>. 61<p> 62<dt> <strong>FALSE</strong> 63<dd> 64The kernel allocates the region starting at <var>address</var> unless that 65space is already allocated. 66</dl> 67<p> 68<dt> <var>source_task</var> 69<dd> 70[in task send right] 71The port for the task whose address space is to be 72mapped. 73<p> 74<dt> <var>source_address</var> 75<dd> 76[in scalar] 77The starting address for the memory to be mapped from the 78source task. The memory to be mapped will start at the beginning of 79the page containing <var>source_address</var>. If not enough memory exists 80following the address, the kernel does not map the memory. 81<p> 82<dt> <var>copy</var> 83<dd> 84[in scalar] 85Copy indicator. If true, the kernel copies the region for the 86memory to the specified task's address space. If false, the region is 87mapped read-write. 88<p> 89<dt> <var>cur_protection</var> 90<dd> 91[out scalar] 92The most restrictive current protection for the memory in 93the region. Valid values are obtained by or'ing together the following 94values: 95<dl> 96<p> 97 <dt> <strong>VM_PROT_READ</strong> 98<dd> 99Allows read access. 100<p> 101<dt> <strong>VM_PROT_WRITE</strong> 102<dd> 103Allows write access. 104<p> 105<dt> <strong>VM_PROT_EXECUTE</strong> 106<dd> 107Allows execute access. 108</dl> 109<p> 110<dt> <var>max_protection</var> 111<dd> 112[out scalar] 113The most restrictive maximum protection for the memory 114in the region. Values are the same as for <var>cur_protection</var>. 115<p> 116<dt> <var>inheritance</var> 117<dd> 118[in scalar] 119The initial inheritance attribute for the region. Valid values 120are: 121<dl> 122<p> 123 <dt> <strong>VM_INHERIT_SHARE</strong> 124<dd> 125Allows child tasks to share the region. 126<p> 127<dt> <strong>VM_INHERIT_COPY</strong> 128<dd> 129Gives child tasks a copy of the region. 130<p> 131<dt> <strong>VM_INHERIT_NONE</strong> 132<dd> 133Provides no access to the region for child tasks. 134</dl> 135</dl> 136<h3>DESCRIPTION</h3> 137<p> 138The <strong>vm_remap</strong> function maps the memory objects underlying 139a portion of the 140specified <var>source_task</var>'s virtual address space into the address 141space belonging to 142<var>target_task</var>. The target task can be the calling task or another 143task, identified by 144its task kernel port. The effect is as if the target task performed 145a <strong>vm_map</strong> call 146given the same memory object, maximum protection, current 147protection, and inheritance as the source task. 148However, the two 149tasks must reside on the same host. The kernel maps the memory objects 150starting at <var>target_address</var>, so that access to <var>target_address</var> 151is as if the source task 152accessed its <var>source_address</var>. 153<p> 154The <var>mask</var> parameter 155specifies additional alignment restrictions on the kernel's 156selection of the starting address. Uses for this mask include: 157<ul> 158<li> 159Forcing the memory address alignment for a mapping to be the same as the 160alignment within the source task. 161<li> 162Quickly finding the beginning of an allocated region by performing bit 163arithmetic on an address known to be in the region. 164<li> 165Emulating a larger virtual page size. 166</ul> 167The <var>cur_protection</var> and <var>max_protection</var> parameters return the protection 168attributes for the mapped memory. If all memory within the range had the same 169attributes, these attributes are returned; otherwise the call returns the most 170restrictive values for any memory in the region. 171<h3>NOTES</h3> 172<p> 173This interface is machine word length specific because of the virtual address 174parameter. 175<h3>RETURN VALUES</h3> 176<dl> 177<p> 178 <dt> <strong>KERN_NO_SPACE</strong> 179<dd> 180There is not enough space in the task's address space to allocate the 181new region for the memory object. 182<p> 183<dt> <strong>KERN_PROTECTION_FAILURE</strong> 184<dd> 185Specified memory is valid, but the backing memory manager is 186not permitted by the requesting task. 187</dl> 188<h3>RELATED INFORMATION</h3> 189<p> 190Functions: 191<a href="vm_map.html"><strong>vm_map</strong></a>, 192<a href="vm_read.html"><strong>vm_read</strong></a>, 193<a href="vm_write.html"><strong>vm_write</strong></a>. 194