I386_IOPL(2) BSD/i386 System Calls Manual I386_IOPL(2)NAME
i386_iopl -- change the i386 I/O privilege level
LIBRARY
i386 Architecture Library (libi386, -li386)
SYNOPSIS
#include <sys/types.h>
#include <machine/sysarch.h>
int
i386_iopl(int iopl);
DESCRIPTION
i386_iopl() sets the i386 I/O privilege level to the value specified by iopl. This call is restricted to the super-user.
RETURN VALUES
Upon successful completion, i386_iopl() returns 0. Otherwise, a value of -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
i386_iopl() will fail if:
[EPERM] The caller was not the super-user, or the operation was not permitted at the current security level.
REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
WARNING
You can really hose your machine if you enable user-level I/O and write to hardware ports without care.
BSD April 12, 2004 BSD
Check Out this Related Man Page
I386_VM86(2) BSD/i386 System Calls Manual I386_VM86(2)NAME
i386_vm86 -- set virtual 8086 processor registers and mode
LIBRARY
i386 Architecture Library (libi386, -li386)
SYNOPSIS
#include <sys/types.h>
#include <signal.h>
#include <machine/mcontext.h>
#include <machine/segments.h>
#include <machine/sysarch.h>
#include <machine/vm86.h>
int
i386_vm86(struct vm86_struct *vmcp);
DESCRIPTION
i386_vm86() will set the process into virtual 8086 mode using the registers and selectors specified by the context pointed to by vmcp. The
processor registers are set from vmcp->substr.regs, and the emulated processor type from vmcp->substr.ss_cpu_type.
The kernel keeps a pointer to the context, and uses the tables stored at vmcp->int_byuser and vmcp->int21_byuser for fast virtual interrupt
handling. If the n th bit is clear in the first of these arrays, then the kernel may directly emulate the real-mode x86 INT n instruction
handling. If the n th bit is set, then the process is delivered a signal when an INT instruction is executed.
Since MS-DOS puts many DOS functions onto interrupt 21, it is handled specially: the k th bit in the vmcp->int21_byuser array is checked
when INT 21 is requested and the ah register is k.
RETURN VALUES
This routine does not normally return: 32-bit mode will be restored by the delivery of a signal to the process. In case of an error in set-
ting the VM86 mode, a value of -1 is returned and the global variable errno is set to indicate the error.
ERRORS
i386_vm86() will fail if:
[EFAULT] The state at vmcp was not readable to the user process.
REFERENCES
i386 Microprocessor Programmer's Reference Manual, Intel
BSD February 20, 1996 BSD
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