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I386_VM86(2)		    BSD	System Calls Manual		  I386_VM86(2)

NAME
     i386_vm86 -- control vm86-related functions

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <machine/sysarch.h>
     #include <machine/vm86.h>

     int
     i386_vm86(int function, void *data);

DESCRIPTION
     The i386_vm86() system call is used to call various vm86 related func-
     tions.  The function argument can be one of the following values:

	   VM86_INIT	 This will initialize the kernel's vm86	parameter area
			 for the process, and permit the process to make vm86
			 calls.	 The data argument points to the following
			 structure:

			 struct	vm86_init_args {
				 int	 debug;
				 int	 cpu_type;
				 u_char	 int_map[32];
			 };

			 The debug argument is used to turn on debugging code.
			 The cpu_type argument controls	the type of CPU	being
			 emulated, and is currently unimplemented.  The
			 int_map argument is a bitmap which determines whether
			 vm86 interrupts should	be handled in vm86 mode, or
			 reflected back	to the process.	 If the	Nth bit	is
			 set, the interrupt will be reflected to the process,
			 otherwise it will be dispatched by the	vm86 interrupt
			 table.

	   VM86_INTCALL	 This allows calls to be made to vm86 interrupt	han-
			 dlers by the process.	It effectively simulates an
			 INT instruction.  data	should point to	the following
			 structure:

			 struct	vm86_intcall_args {
				 int	 intnum;
				 struct	 vm86frame vmf;
			 };

			 intnum	specifies the operand of INT for the simulated
			 call.	A value	of 0x10, for example, would often be
			 used to call into the VGA BIOS.  vmf is used to ini-
			 tialize CPU registers according to the	calling	con-
			 vention for the interrupt handler.

	   VM86_GET_VME	 This is used to retrieve the current state of the
			 Pentium(r) processor's	VME (Virtual-8086 Mode Exten-
			 sions)	flag, which is bit 0 of	CR4.  data should be
			 initialized to	point to the following:

			 struct	vm86_vme_args {
				 int	 state;			 /* status */
			 };

			 state will contain the	state of the VME flag on re-
			 turn.

     vm86 mode is entered by calling sigreturn(2) with the correct machine
     context for vm86, and with	the PSL_VM bit set.  Control returns to	the
     process upon delivery of a	signal.

RETURN VALUES
     The i386_vm86() function returns the value	0 if successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The i386_vm86() system call will fail if:

     [EINVAL]		The kernel does	not have vm86 support, or an invalid
			function was specified.

     [ENOMEM]		There is not enough memory to initialize the kernel
			data structures.

AUTHORS
     This man page was written by Jonathan Lemon, and updated by Bruce M
     Simpson.

BSD				 July 27, 1998				   BSD

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | AUTHORS

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