cvt.save

explore2fs-1.07 source code

Int 31H Function 0E01H [1.0]

Set Coprocessor Emulation

Enables or disables the numeric coprocessor for this virtual
machine  and the reflection of coprocessor exceptions to the
client.

Call With:

   AX     = 0E01H
   BX     = coprocessor bits

           Bit    Significance
           0      new value of MPv bit for client's virtual
           CR0
                  0 = disable numeric coprocessor for this
           client
                  1 = enable numeric coprocessor for this
           client
           1      new value of EMv bit for client's virtual
           CR0
                  0 = client will not supply coprocessor
           emulation
                  1 = client will supply coprocessor
           emulation
           2-15   not applicable


Returns:

   if function successful
   Carry flag= clear

   if function unsuccessful
   Carry flag= set
   AX     = error code
           8026H   invalid request (client requested
                   disabling coprocessor on a processor
                   which does not support this)

Notes:

o  If the MPv bit is not set, the host may not need to save
   the coprocessor state for this virtual machine to improve
   system performance.
o  If the virtual EM (EMv) bit is set, the host delivers all
   coprocessor exceptions to the client, so that the client
   can provide its own floating point emulation (whether or
   not a coprocessor is present or the host also has a
   floating point emulator).  In other words, if the EMv bit
   is set, the host sets the EM bit in the real CR0 while
   the client is active, and reflects coprocessor not
   present faults (Int 7) to the client.
o  Floating point emulation can be tested on a system with a
   numeric coprocessor by using this function to enable
   client handling of coprocessor exceptions and disable the
   coprocessor.
o  The client should use Int 31H Function 0212H to register
   an exception handler for coprocessor not present faults
   (Int 7) prior to setting the EMv bit with this function.
o  A client can determine the CPU type with Int 31H Function
   0400H, and the presence or absence of a coprocessor with 
   Int 31H Function 0E00H.  The client should not draw any
   conclusions about the presence or absence of a
   coprocessor based on the CPU type alone.