|
include vmm.inc VMMcall _Allocate_GDT_Selector, <DescDWORD1, DescDWORD2, flags> mov ecx, eax ; zero in eax and edx if error or ecx, edx jz error mov [Selector], eax ; new selector mov word ptr [GDTSel], dx ; selector for the GDT ror edx, 10h mov word ptr [SelCount], dx ; number of selectors in GDT |
The _Allocate_GDT_Selector service creates a new selector and adds it to the Global Descriptor Table (GDT).
DescDWORD1
Specifies the high doubleword of the descriptor for the selector. This parameter contains the high 16 bits of the base address, the high 4 bits of the limit, and the status and type bits.
DescDWORD2
Specifies the low doubleword of the descriptor for the selector. This parameter contains the low 16 bits of the base address and limit.
flags
Specifies the operation flags. This parameter must be set to 0.
If the service is successful, the EAX and EDX registers contain the following values:
| Register | Description |
| EAX | Contains the new selector. |
| EDX | Contains the selector for and the size of the GDT. The low 16 bits contains the selector for the GDT, and the high 16 bits contains the size of the GDT expressed as the number of selectors in the table. |
If an error occurs, such as an invalid descriptor value or the GDT is full, the EAX and EDX registers contain zero to indicate an error.
Although this service returns the selector for the GDT, virtual devices should
not attempt to edit the GDT directly. Virtual devices can instead use the
_SetDescriptor service to change selectors in the GDT.
Virtual devices should use the BuildDescriptorDWORDs service to set the DescDWORD1 and DescDWORD2 parameters to the appropriate values.
This service sets the RPL of the selector to the DPL of the selector set in the DescDWORD1 parameter.
EAX, EDX