.\" $OpenBSD: pcibios.4,v 1.4 2001/01/09 18:41:34 krw Exp $
.\" $NetBSD: pcibios.4,v 1.7 2000/08/03 13:32:39 soda Exp $
.\"
.\" Copyright (c) 2000 Michale Shalayeff, All rights reserved.
.\" Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Lennart Augustsson.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
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.\"    must display the following acknowledgement:
.\"        This product includes software developed by the NetBSD
.\"        Foundation, Inc. and its contributors.
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.Dd July 22, 2000
.Dt PCIBIOS 4
.Os
.Sh NAME
.Nm pcibios
.Nd introduction to PCI BIOS support
.Sh SYNOPSIS
.Cd "pcibios0 at bios0 flags 0x0000"
.Cd "option	PCIBIOSVERBOSE"
.\" .Cd "#options  PCIBIOS_IRQS_HINT=0x0a00 #IRQ 9,11"
.\" .Cd "#options  PCIBIOS_INTR_FIXUP_FORCE"
.\" .Cd "options   PCIBIOS_INTR_GUESS"
.\" .Cd "#options  PCIINTR_DEBUG"
.Pp
.Sh INTRODUCTION
.Ox
provides support for setting up PCI controllers, bridges, and devices
using information extracted from the BIOS.
.Pp
Ideally, the boot firmware of a machine (a.k.a. BIOS) should set
up all PCI devices; assigning them I/O and memory addresses and
interrupts.  Alas, this does not always happen, so there is some
PC specific code that can do the initialization when
.Ox
boots.
.Pp
Flags is a bit mask each bit of which specifies a fixup procedure to
omit. The following list specifies these procedures and gives
flags bit values to disable them in case they cause problems.
.Pp
.Bl -tag -width 0x0000
.It 0x0001
Fixup PCI I/O and memory addresses.
.Pp
Some BIOS implementations don't allocate I/O space and
memory space for all PCI devices. Especially, a BIOS
which has
.Qq PnP OS mode
enabled shows this behavior.
Since necessary space isn't allocated, those devices
will not work without special handling.
.Pp
Without this flag force allocation of I/O space and memory space
instead of relying upon the BIOS to do so.
.Pp
If necessary space is already correctly assigned to the devices,
this option leaves the space as is.
.Pp
Although many BIOS implementations leave CardBus bridges'
space unallocated, the CardBus bridge device driver doesn't
require this option, since the driver allocates necessary space
by itself.
.It 0x0002
Fixup PCI bus numbering; needed for many
.Xr cardbus 4
bridges.
.Pp
Each PCI bus and CardBus should have a unique bus number.
But some BIOS implementations don't assign a bus number
for subordinate PCI buses. And many BIOS implementations
don't assign a bus number for CardBuses.
.Pp
A typical symptom of this is the following boot message:
.D1 Sy cardbus0 at cardslot0: bus 0 device 0...
Please note that this cardbus0 has a bus number
.Sq 0 ,
but normally the bus number 0 is used by the machine's
primary PCI bus. Thus, this bus number for cardbus is
incorrect
.Pq not assigned .
In this situation, a device located in cardbus0 doesn't
show correct device ID,
because its bus number 0 incorrectly refers to the primary
PCI bus, and a device ID in the primary PCI bus is shown
in the boot message instead of the device's ID in the cardbus0.
.Pp
Without this flag force assignment of bus numbers for all subordinate
PCI buses and CardBuses.
.Pp
Since this procedure renumbers all PCI buses and CardBuses,
all bus numbers of subordinate buses become different
when this option is enabled.
.It 0x0004
Fixup PCI interrupt routing.
.Pp
Some BIOS implementations don't assign an interrupt for
some devices.
.Pp
This procedure assigns an interrupt for such devices instead
of relying upon the BIOS to do so.
.Pp
If the BIOS has already assigned an interrupt to a device, this
procedure leaves the interrupt as is.
.\" .It Nm PCIBIOS_IRQS_HINT
.\" hint for IRQ use.
.\" When the
.\" .Em PCIBIOS_INTR_FIXUP
.\" cannot guess an adequate IRQ for a device, the hint is used.
.\" .Pp
.\" The value is a logical or of power-of-2s of allowable interrupts:
.\" .Bl -column "XX-0xffff" "XX-0xffff" "XX-0xffff" "XX-0xffff" -compact -offset 2n
.\" .It Em   "IRQ Value" Em "\tIRQ Value" Em "\tIRQ Value" Em "\tIRQ Value"
.\" .It    "\& 0 0x0001"    "\t 4 0x0010"    "\t 8 0x0100"    "\t12 0x1000"
.\" .It    "\& 1 0x0002"    "\t 5 0x0020"    "\t 9 0x0200"    "\t13 0x2000"
.\" .It    "\& 2 0x0004"    "\t 6 0x0040"    "\t10 0x0400"    "\t14 0x4000"
.\" .It    "\& 3 0x0008"    "\t 7 0x0080"    "\t11 0x0800"    "\t15 0x8000"
.\" .El
.\" For example,
.\" .Qq Sy options PCIBIOS_IRQS_HINT=0x0a00
.\" allows IRQ 9 and IRQ 11.
.\"
.\" The kernel global variable
.\" .Va pcibios_irqs_hint
.\" holds this value,
.\" so a user can override this value without kernel recompilation.
.\" For example:
.\" .Bl -bullet -compact
.\" .It
.\" To specify this value on the fly, type the following command
.\" at the boot prompt to drop into DDB (the in-kernel debugger;
.\" you have to specify
.\" .Qq Sy options DDB
.\" to make kernel with DDB):
.\" .Dl Ic boot -d
.\" And type the following command on
.\" .Qq Sy db>
.\" prompt:
.\" .Dl Ic write pcibios_irqs_hint 0x0a00
.\" Then type the following to continue to boot:
.\" .Dl Ic c
.\" .It
.\" To modify kernel image without kernel recompilation,
.\" run the following command on shell:
.\" .Dl Ic gdb --write /netbsd
.\" And type the following commands at the
.\" .Qq Sy (gdb)
.\" prompt:
.\" .Dl Ic set pcibios_irqs_hint=0xa00
.\" .Dl Ic quit
.\" .El
.\"
.\" .It Nm PCIBIOS_INTR_FIXUP_FORCE
.\" .Pp
.\" Some buggy BIOS implementations provide inconsistent
.\" information between the PCI Interrupt Configuration Register
.\" and the PCI Interrupt Routing table. In such case,
.\" the PCI Interrupt Configuration Register takes precedence
.\" by default. If this happens, a kernel with
.\" .Em PCIBIOSVERBOSE
.\" shows
.\" .Qq Sy WARNING: preserving irq XX
.\" in the PCI routing table.
.\"
.\" If
.\" .Em PCIBIOS_INTR_FIXUP_FORCE
.\" is specified in addition to the
.\" .Em PCIBIOS_INTR_FIXUP ,
.\" the PCI Interrupt Routing table takes precedence.
.\" In this case, a kernel with
.\" .Em PCIBIOSVERBOSE
.\" shows
.\" .Qq Sy WARNING: overriding irq XX
.\" in the PCI routing table.
.\"
.\" The necessity of this option is doubtful, and we may
.\" remove this option in the future. If you find that this
.\" option is worth preserving, please report it with send-pr.
.\"
.\" .It Nm PCIBIOS_INTR_GUESS
.\" make
.\" .Em PCIBIOS_INTR_FIXUP
.\" work with unknown interrupt router.
.\" .Pp
.\" If a PCI interrupt router is not known, normally interrupt
.\" configuraion will not be touched.
.\"
.\" But if
.\" .Em PCIBIOS_INTR_GUESS
.\" is specified in addition to the
.\" .Em PCIBIOS_INTR_FIXUP ,
.\" and if a PCI interrupt routing table entry indicates that only
.\" one IRQ is available for the entry, the IRQ is assumed to be already
.\" connected to the device, and corresponding PCI Interrupt
.\" Configuration Register will be configured accordingly.
.\"
.\" .It Nm PCIINTR_DEBUG
.\" make the
.\" .Em PCIBIOS_INTR_FIXUP
.\" procedure verbose.
.\"
.\" .El
.Sh SEE ALSO
.Xr cardbus 4 ,
.Xr pci 4
.Sh HISTORY
The
.Nm
code appeared in
.Nx 1.5 .
.Ox
support was added in
.Ox 2.8 .
In contrast to
.Nx
implementation
.Nm
in
.Ox
is a real device, where options control is done through the
.Nm flags
wich are modifiable through the
.Xr boot_config 8
interface.
.Sh BUGS
The
.Em PCIBIOS Adress Fixup
option may conflict with the PCI CardBus driver's own
address fixup.