_GetAppFlatDSAlias

The _GetAppFlatDSAlias service returns a ring-3, read-only, GDT selector that provides access to the same memory as the system's ring-0 data segment selector. Virtual devices use this service to support protected-mode APIs that let protected-mode applications read from the same memory as the virtual device.

Parameter

This service has no parameters.

Return Value

The EAX register contains the selector.

Comments

Since more than one virtual device may use this selector, a virtual device must never attempt to free the selector using the _Free_GDT_Selector service. Also, a virtual device should not attempt to create a read/write selector using this selector. If a virtual device requires an application to write to any portion of system memory, the virtual device should build its own selector with a base and limit that specifies just the memory the application must modify.

Uses

EAX

See Also

_Free_GDT_Selector