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include vmm.inc
 
VMMcall _PageUnLock, <hMem, nPages, PageOff, flags>
 
or      eax, eax            ; nonzero if unlocked, zero if error
jz      not_unlocked
 
The _PageUnLock service unlocks one or more pages in the specified memory
block.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
hMem       Specifies a handle identifying the memory block to unlock. This
           handle must have been previously created using the PageAllocate
           or PageReAllocate service.
 
nPages     Specifies the number of pages to unlock.
 
PageOff    Specifies the offset in pages from the start of the block to the
           first page to unlock.
 
flags      Specifies the operation flags. This parameter can be a
           combination of the following values:
 
           Value            Meaning
           ─────────────────────────────────────────────────────────────────
           PageLockedIfDP   Unlock pages only if the virtual pageswap device
                            use MS-DOS or BIOS functions to write to the
                            hardware. If the virtual pageswap device writes
                            directly to the hardware, this service returns
                            immediately without unlocking the pages.
 
                            The PageLockedIfDP value cannot be used until
                            after the Init_Complete message has been
                            processed.
 
           PageMarkPageOut  Marks pages for immediate swapping if this
                            service sets the lock count for the pages to
                            zero. This service marks the pages by clearing
                            the P_ACC bit for each page. The PageMarkPageOut
                            value should only be used if the pages are
                            unlikely to be accessed for some time.
 
           All other values are reserved.
 
Return Value
 
The EAX register contains a nonzero value if the service is successful.
Otherwise, EAX contains zero to indicate an error, such as an invalid memory
handle.
 
Comments
 
This service returns an error if the sum of the PageOff and nPages
parameters is greater than the number of pages in the memory block. It also
returns an error if the specified pages are not already locked.
 
Each page in a memory block has an individual lock count. This service
increments the lock count each time the page is locked, and decrements the
count each time the page is unlocked. The lock count must be zero for the
page to be unlocked. This means that if the handle is locked 5 times, it has
to be unlocked 5 times. Virtual devices must not leave handles locked when
not needed.
 
Uses
 
EAX
 
See Also
 
_PageLock
 
 
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