123 lines
4.1 KiB
Groff
123 lines
4.1 KiB
Groff
.\" $NetBSD: bioscall.9,v 1.1 1998/10/01 02:33:51 jtk Exp $
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.\"
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.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by John Kohl.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd October 1, 1998
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.Dt BIOSCALL 9 i386
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.Os NetBSD
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.Sh NAME
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.Nm bioscall
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.Nd call system BIOS function from real mode
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.Sh SYNOPSIS
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.Fd #include <i386/bioscall.h>
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.Ft void
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.Fn bioscall "int function" "struct bioscallregs *regs"
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.Sh DESCRIPTION
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The
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.Nm
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function switches the processor into real mode, calls the BIOS interrupt
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numbered
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.Fa function ,
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and returns to protected mode.
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.Pp
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This function is intended to be called during the initial system
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bootstrap when necessary to probe devices or pseudo-devices.
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.Pp
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The register values specified by
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.Fa *regs
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(with one exception) are installed before the BIOS interrupt is called.
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The processor flags are handled specially. Only the following flags are
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passed to the
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BIOS from the registers in
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.Fa regs
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(the remainder come from the processor's flags register at the time
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of the call):
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.Ar PSL_C ,
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.Ar PSL_PF ,
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.Ar PSL_AF ,
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.Ar PSL_Z ,
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.Ar PSL_N ,
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.Ar PSL_D ,
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.Ar PSL_V .
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.Pp
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The
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.Va bioscallregs
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structure is defined to contain structures for each register, to allow
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access to 32-, 16- or 8-bit wide sections of the registers.
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Definitions are provided which simplify access to the union members.
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.Sh RETURN VALUE
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.Nm
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fills in
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.Fa *regs
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with the processor registers as returned from the BIOS call.
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.Sh EXAMPLES
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The Advanced Power Management driver calls
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.Nm
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by setting up a register structure with the APM installation check and
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device types in registers
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.Fa ax
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and
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.Fa bx ,
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then calls the BIOS to fetch the details for calling the APM support
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through a protected-mode interface. The BIOS returns these details in
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the registers:
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.Pp
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.Bd -literal
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#include <i386/bioscall.h>
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#include <i386/apmvar.h>
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struct bioscallregs regs;
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regs.AX = APM_BIOS_FN(APM_INSTALLATION_CHECK);
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regs.BX = APM_DEV_APM_BIOS;
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regs.CX = regs.DX = 0;
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regs.ESI = regs.EDI = regs.EFLAGS = 0;
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bioscall(APM_SYSTEM_BIOS, ®s);
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.Ed
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.Pp
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.Sh CODE REFERENCES
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.Pa sys/arch/i386/i386/bioscall.s ,
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.Pa sys/arch/i386/bioscall/biostramp.S
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.Sh REFERENCES
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.Xr apm 4
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.Sh HISTORY
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.Nm
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first appeared in NetBSD-1.3.
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.Sh BUGS
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Not all BIOS functions are safe to call through the trampoline, as they
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may depend on system state which has been disturbed or used for other
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purposes once the
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.Nx
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kernel is running.
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