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include vmm.inc
 
VMMcall _MapPhysToLinear, <PhysAddr, nBytes, flags>
 
cmp     eax, 0FFFFFFFFh     ; 0FFFFFFFFh if not addressable
je      not_addressable
mov     [Address], eax      ; address of first byte
 
The _MapPhysToLinear service returns the linear address of the first byte in
the specified range of physical addresses.
 
Parameter  Description
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PhysAddr   Specifies the 32-bit physical address of the start of the region
           to examine. Physical addresses start at 0, thus the address of
           physical page 0A0h is 0A0000h.
 
nBytes     Specifies the length in bytes of the physical region. The service
           uses this parameter to verify that the entire range is
           addressable.
 
flags      Specifies the operation flags. This parameter must be set to 0.
 
Return Value
 
The EAX register contains the ring-0 linear address of the first byte of the
physical region if this service is successful. Otherwise, EAX contains
0FFFFFFFFh if the specified range is not addressable.
 
Comments
 
This service is intended to be used to examine device-specific physical
memory. Virtual devices must not use this service for any other purpose.
 
Since physical addresses do not move, the linear address returned by this
service remains valid even after the virtual device returns from the
Device_Init message.
 
Example
 
The following example returns a linear address for the physical page A0h:
 
VMMcall _MapPhysToLinear,<0A0000h,10000h,0>
 
Since physical memory is mapped contiguously, the linear address for page
0A1h is 4096 bytes beyond the return linear address.
 
Uses
 
EAX
 
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