VideoPortAllocatePool - NtDoc
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headers
// video.h
VIDEOPORT_API PVOID VideoPortAllocatePool(
[in] IN PVOID HwDeviceExtension,
[in] IN VP_POOL_TYPE PoolType,
[in] IN SIZE_T NumberOfBytes,
[in] IN ULONG Tag
);
View the official Windows Driver Kit DDI referenceNo description available.
The VideoPortAllocatePool function allocates a block of pool memory, inserting a caller-supplied tag at the beginning of the memory.
HwDeviceExtension [in]Pointer to the miniport driver's device extension.
PoolType [in]Specifies the type of memory pool to allocate. This parameter can be set to one of the following:
| Value | Meaning |
|---|---|
| VpNonPagedPool | The pool is from nonpaged memory. |
| VpPagedPool | The pool is from paged memory. |
| VpNonPagedPoolCacheAligned | The pool is from cache-aligned, nonpaged memory. |
| VpPagedPoolCacheAligned | The pool is from cache-aligned, paged memory. |
NumberOfBytes [in]Specifies the number of bytes of memory to allocate.
Tag [in]Specifies a four-byte allocation tag, consisting of up to four ASCII characters, that uniquely identifies the driver that is allocating the memory. The tag string is delimited with single quotes.
On successful allocation of the memory pool, VideoPortAllocatePool returns the address of the allocated memory pool. Otherwise, this function returns NULL.
VideoPortAllocatePool is intended to replace VideoPortAllocateBuffer, which is obsolete.
The Tag string should be specified in byte-reversed order. It is recommended that the first letter in the string (before it is reversed) be 'D' to denote a display driver; the other three bytes should be indicative of the driver name. For example, the Tag string 'zyxD' appears as 'Dxyz' if pool is dumped. The tag appears in any crash dump of the system that occurs.
Callers of VideoPortAllocatePool can be running at IRQL = DISPATCH_LEVEL only if the requested PoolType is one of the VpNonPagedXxx types. Otherwise, callers must be running at IRQL < DISPATCH_LEVEL.