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include vmm.inc
 
VMMcall _PageLock, <hMem, nPages, PageOff, flags>
 
or      eax, eax        ; nonzero if locked, zero if error
jz      not_locked
 
The _PageLock service locks one or more pages in the specified memory
block.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
hMem       Specifies a handle identifying the memory block to lock. This
           handle must have been previously created using the _PageAllocate
           or _PageReAllocate service.
 
nPages     Specifies the number of pages to lock.
 
PageOff    Specifies the offset in pages from the start of the memory block
           to the first page to lock.
 
flags      Specifies the operation flags. This parameter can be the
           following value:
 
           Value           Meaning
           ─────────────────────────────────────────────────────────────────
           PageLockedIfDP  Lock pages only if the virtual pageswap device
                           uses MS-DOS or BIOS function to write pages to
                           the hardware. If the virtual pageswap device
                           writes directly to the hardware, this service
                           returns immediately without locking the pages.
 
                           The PageLockedIfDP value cannot be used until
                           after the Init_Complete message has been
                           processed.
 
           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 invalid memory
handle or insufficient memory.
 
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.
 
This service has no affect on memory blocks allocated using the PageFixed
value; such memory is always locked.
 
Virtual devices must not assume that the requested number of pages can
always be 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
 
_PageAllocate, _PageUnlock
 
 
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