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include vmm.inc
 
VMMcall _TestGlobalV86Mem, <VMLinAddr, nBytes, flags>
 
mov     [Result], eax           ; 0 if local, 1 if global, 2 if mixed,
                                ; 3 if includes instance data region
 
The _TestGlobalV86Mem service tests whether a V86 address range is global,
local, or instanced.
 
Parameter  Description
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VMLinAddr  Specifies the ring-0 linear address of the first byte of the V86
           address range. For example, the linear address of the V86 address
           02C1h:0FC5h is 3BD5h (02C10h + 0FC5h).
 
nBytes     Specifies the size in bytes of the V86 address range.
 
flags      Specifies the operation flags. This parameter must be set to 0.
 
Return Value
 
The EAX register contains one of the following values:
 
Value  Meaning
────────────────────────────────────────────────────────────────────────────
0      Address range either contains local memory, or is not a valid V86
       address range.
 
1      Address range contains global memory.
 
2      Address range contains both local and global memory.
 
3      Address range contains global memory, but also includes an instance
       data region.
 
Comments
 
Global V86 memory has addresses that are valid and identical in all virtual
machines. Local memory has addresses that are only valid in one virtual
machine. Instanced memory has addresses that are valid in all virtual
machines, but the content of the memory varies with each virtual machine.
 
This service may incorrectly report the type of memory in addresses above
page 0A0h (in the device adapter area). If this service returns global for
memory in this area, it is global. If the service returns local, however,
the memory may actually be global. Generally, this region is local.
 
Operations involving global address ranges typically do not need to be
virtualized since the range is valid and addressable in all virtual
machines. Operations involving local address ranges may have to be
virtualized since it is possible for software, such as an interrupt handler,
to use a local address in the wrong virtual machine.
 
Uses
 
EAX
 
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