Allocate Linear Memory Block
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Allocates a block of page-aligned linear address space. The
base address of the block may be specified by the client,
and pages within the block may be committed or uncommitted.
Call With
AX = 0504H
EBX = desired page-aligned linear address of memory
block,
or zero if linear address unspecified
ECX = size of block (bytes, must be nonzero)
EDX = flags
| Bit | Significance |
|---|
| 0 | 0 = create uncommitted pages |
| 1 = create committed pages |
| 1-31 | reserved, should be zero |
Returns
if function successful
Carry flag = clear
EBX = linear address of memory block
ESI = handle for memory block
if function unsuccessful
Carry flag = set
AX = error code
| 8001H | unsupported function (16-bit host) |
| 8012H | linear memory unavailable |
| 8013H | physical memory unavailable |
| 8014H | backing store unavailable |
| 8016H | handle unavailable |
| 8021H | invalid value (ECX = 0) |
| 8025H | invalid linear address (EBX not page aligned) |
Notes
- A DPMI 1.0 host that is 16-bit only will not support this
function.
- A 16-bit client of a 32-bit DPMI 1.0 host can use this
function.
- The allocated block is always page-aligned. If a specific linear
address is not requested (EBX = 0), the DPMI host allocates the memory
block at any available page-aligned linear address. If a specific
linear address is requested (EBX nonzero), the host either allocates
the block at the specified address or returns error code 8012H (linear memory
unavailable).
- Int 31H Function 0501H, which can also
be used to allocate linear memory blocks, does not necessarily
page-align its blocks and does not have the ability to create
uncommitted pages or allocate a block at a specific linear
address.