.\"	$NetBSD: pcictl.8,v 1.21 2026/01/25 00:59:36 uwe Exp $
.\"
.\" Copyright 2001 Wasabi Systems, Inc.
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.\" Written by Jason R. Thorpe for Wasabi Systems, Inc.
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.Dd January 25, 2026
.Dt PCICTL 8
.Os
.
.Sh NAME
.Nm pcictl
.Nd a program to manipulate the PCI bus
.
.Sh SYNOPSIS
.Nm
.Ar pcibus
.Ar command
.Op Ar arg \&...
.
.Sh DESCRIPTION
.Nm
allows a user or system administrator to access various resources
on a
.Tn PCI
bus.
The
.Ar pcibus
argument names a special file for the
.Tn PCI
bus device.
If the file name is relative, it's interpreted relative to the
.Pa /dev
directory, so e.g. plain
.Ql pci0
refers to
.Pa /dev/pci0 .
.
.Pp
The following
.Ar command\^ Ns s
are available:
.
.Bl -tag -width Cm
.
.It Xo
.Cm list
.Op Fl Nn
.Op Fl b Ar bus
.Op Fl d Ar device
.Op Fl f Ar function
.Xc
List the devices in the
.Tn PCI
domain, either as names or, if
.Fl n
is given, as numbers.
.Pp
If
.Fl N
is given, the driver name for this
.Tn PCI
device will be listed if any driver is attached.
.Pp
Any locator not specified defaults
to a wildcard, or may be explicitly wildcarded by specifying
.Sq Li all ,
or
.Sq Li any .
.
.El
.\"
.Pp
The remaining commands operate on a single
.Tn PCI
device, the
.Fl d
argument is mandatory.
If the bus is not specified, it defaults to the bus number of the
.Ar pcibus .
If the function is not specified, it defaults to 0.
.
.Bl -tag -width Cm
.
.It Xo
.Cm dump
.Op Fl b Ar bus
.   Fl d Ar device
.Op Fl f Ar function
.Xc
Dump the
.Tn PCI
configuration space for the specified device.
.
.It Xo
.Cm read
.Op Fl b Ar bus
.   Fl d Ar device
.Op Fl f Ar function
.Ar register
.Xc
Read the specified 32-bit aligned
.Tn PCI
configuration
.Ar register
and print it in hexadecimal to standard output.
.
.It Xo
.Cm write
.Op Fl b Ar bus
.   Fl d Ar device
.Op Fl f Ar function
.Ar register
.Ar value
.Xc
Write the specified
.Ar value
to the specified 32-bit aligned
.Tn PCI
configuration
.Ar register .
.
.El
.
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/pci*
.Tn PCI
bus device nodes
.El
.
.Sh EXAMPLES
This shows all
.Tn PCI
devices on the system:
.Pp
.Dl pcictl pci0 list
.Pp
This shows all
.Tn PCI
devices on the system, including attached drivers:
.Pp
.Dl pcictl pci0 list -N
.
.Sh SEE ALSO
.Xr pci 3 ,
.Xr pci 4 ,
.Xr drvctl 8
.
.Sh HISTORY
The
.Nm
command first appeared in
.Nx 1.6 .
.
.Sh CAVEATS
.Nm
.Cm read
and
.Cm write
are dangerous commands that can damage hardware
and panic the operating system.
They are meant as a diagnostic tool for experiments or to debug device
drivers.
Do not use them as substitutes for a device driver!