usr.sbin/pciconf/pciconf.8

.\" Copyright (c) 1997
.\"	Stefan Esser <se@FreeBSD.org>. All rights reserved.
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.Dd September 5, 2026
.Dt PCICONF 8
.Os
.Sh NAME
.Nm pciconf
.Nd diagnostic utility for the PCI bus
.Sh SYNOPSIS
.Nm
.Fl l Oo Fl BbceVv Oc Op Ar device
.Nm
.Fl t Oo Fl v Oc
.Nm
.Fl a Ar device
.Nm
.Fl r Oo Fl b | h Oc Ar device addr Ns Op : Ns Ar addr2
.Nm
.Fl w Oo Fl b | h Oc Ar device addr value
.Nm
.Fl D Oo Fl b | h | x Oc Ar device bar Op Ar start Op Ns Ar count
.Nm
.Fl R Oo Fl b | h | x Oc Ar device bar start Ns Op : Ns Ar end
.Nm
.Fl W Oo Fl b | h | x Oc Ar device bar offset value
.Sh DESCRIPTION
The
.Nm
utility provides a command line interface to functionality provided by the
.Xr pci 4
.Xr ioctl 2
interface.
As such, some of the functions are only available to users with write
access to
.Pa /dev/pci ,
normally only the super-user.
.Pp
A
.Ar device
can be identified either by a device name if the device is
attached to a driver or by a selector.
Selectors identify a PCI device by its address in PCI config space and
can take one of the following forms:
.Pp
.Bl -bullet -offset indent -compact
.It
.Li pci Ns Va domain Ns \&: Ns Va bus Ns \&: Ns Va device Ns \&: \
Ns Va function Ns
.It
.Li pci Ns Va bus Ns \&: Ns Va device Ns \&: Ns Va function Ns
.It
.Li pci Ns Va bus Ns \&: Ns Va device Ns
.El
.Pp
In the case of an abridged form, omitted selector components are assumed to be 0.
An optional leading device name followed by @ and an optional final colon
will be ignored; this is so that the first column in the output of
.Nm
.Fl l
can be used without modification.
All numbers are base 10.
.Ss List Mode
With the
.Fl l
option,
.Nm
lists PCI devices in the following format:
.Bd -literal
foo0@pci0:0:4:0: class=0x010000 rev=0x01 hdr=0x00 vendor=0x1000 device=0x000f \
subvendor=0x0000 subdevice=0x0000
bar0@pci0:0:5:0: class=0x000100 rev=0x00 hdr=0x00 vendor=0x88c1 device=0x5333 \
subvendor=0x0000 subdevice=0x0000
none0@pci0:0:6:0: class=0x020000 rev=0x00 hdr=0x00 vendor=0x10ec device=0x8029 \
subvendor=0x0000 subdevice=0x0000
.Ed
.Pp
The first column gives the
driver name, unit number, and selector.
If there is no driver attached to the
.Tn PCI
device in question, the driver name will be
.Dq none .
Unit numbers for detached devices start at zero and are incremented for
each detached device that is encountered.
The selector
is in a form which may directly be used for the other forms of the command.
The second column is the class code, with the class byte printed as two
hex digits, followed by the sub-class and the interface bytes.
The third column prints the device's revision.
The fourth column describes the header type.
.Pp
Currently assigned header types include 0 for standard devices,
1 for
.Tn PCI
to
.Tn PCI
bridges, and 2 for
.Tn PCI
to
.Tn CardBus
bridges.
If the most significant bit
of the header type register is set for
function 0 of a
.Tn PCI
device, it is a
.Em multi-function
device, which contains several (similar or independent) functions on
one chip.
.Pp
The sixth and seventh columns contain the vendor ID and the device ID of the
device.
The eigth and ninth columns contain subvendor and subdevice IDs, introduced
in revision 2.1 of the
.Tn PCI
standard.
Note that they will be 0 for older cards.
.Pp
Adding a second
.Fl l
option causes output to be in a compact columnar format, suitable for
80 column output:
.Bd -literal
drv     selector        class   rev hdr vendor device subven subdev
foo0@pci0:0:4:0:        010000  01  00  1000   000f   0000   0000
bar0@pci0:0:5:0:        000100  00  00  88c1   5333   0000   0000
none0@pci0:0:6:0:       020000  00  00  10ec   8029   0000   0000
.Ed
.Pp
All fields retain the same definition as with the non-compact form.
.Pp
If the
.Fl B
option is supplied,
.Nm
will list additional information for
.Tn PCI
to
.Tn PCI
and
.Tn PCI
to
.Tn CardBus
bridges,
specifically the resource ranges decoded by the bridge for use by devices
behind the bridge.
Each bridge lists a range of bus numbers handled by the bridge and its
downstream devices.
Memory and I/O port decoding windows are enumerated via a line in the
following format:
.Bd -literal
    window[1c] = type I/O Port, range 16, addr 0x5000-0x8fff, enabled
.Ed
.Pp
The first value after the
.Dq Li window
prefix in the square brackets is the offset of the decoding window in
config space in hexadecimal.
The type of a window is one of
.Dq Memory ,
.Dq Prefetchable Memory ,
or
.Dq I/O Port .
The range indicates the binary log of the maximum address the window decodes.
The address field indicates the start and end addresses of the decoded range.
Finally, the last flag indicates if the window is enabled or disabled.
.Pp
If the
.Fl b
option is supplied,
.Nm
will list any base address registers
.Pq BARs
that are assigned resources for each device.
Each BAR will be enumerated via a line in the following format:
.Bd -literal
    bar   [10] = type Memory, range 32, base 0xda060000, size 131072, enabled
.Ed
.Pp
The first value after the
.Dq Li bar
prefix in the square brackets is the offset of the BAR in config space in
hexadecimal.
The type of a BAR is one of
.Dq Memory ,
.Dq Prefetchable Memory ,
or
.Dq I/O Port .
The range indicates the binary log of the maximum address the BAR decodes.
The base and size indicate the start and length of the BAR's address window,
respectively.
Finally, the last flag indicates if the BAR is enabled or disabled.
.Pp
If the
.Fl c
option is supplied,
.Nm
will list any capabilities supported by each device.
A second invocation of
.Fl c
will print additional data for certain capabilities.
Each capability is enumerated via a line in the following format:
.Bd -literal
    cap 10[40] = PCI-Express 1 root port
.Ed
.Pp
The first value after the
.Dq Li cap
prefix is the capability ID in hexadecimal.
The second value in the square brackets is the offset of the capability
in config space in hexadecimal.
The format of the text after the equals sign is capability-specific.
.Pp
Each extended capability is enumerated via a line in a similar format:
.Bd -literal
ecap 0002[100] = VC 1 max VC0
.Ed
.Pp
The first value after the
.Dq Li ecap
prefix is the extended capability ID in hexadecimal.
The second value in the square brackets is the offset of the extended
capability in config space in hexadecimal.
The format of the text after the equals sign is capability-specific.
.Pp
If the
.Fl e
option is supplied,
.Nm
will list any errors reported for this device in standard PCI error registers.
Errors are checked for in the PCI status register,
the PCI-express device status register,
and the Advanced Error Reporting status registers.
.Pp
If the
.Fl v
option is supplied,
.Nm
will attempt to load the vendor/device information database, and print
vendor, device, class and subclass identification strings for each device.
.Pp
If the
.Fl V
option is supplied,
.Nm
will list any vital product data
.Pq VPD
provided by each device.
Each VPD keyword is enumerated via a line in the following format:
.Bd -literal
    VPD ro PN  = '110114640C0     '
.Ed
.Pp
The first string after the
.Dq Li VPD
prefix indicates if the keyword is read-only
.Dq ro
or read-write
.Dq rw .
The second string provides the keyword name.
The text after the equals sign lists the value of the keyword which is
usually an ASCII string.
.Pp
If the optional
.Ar device
argument is given with the
.Fl l
flag,
.Nm
will only list details about a single device instead of all devices.
.Ss Tree Mode
With the
.Fl t
flag,
.Nm
lists PCI devices in a tree prefixing each device with indentation text showing
the sibling and parent/child relationships.
If the device has an attached driver, the device is identified by the driver
name and unit number;
otherwise, the device is identified by a PCI selector.
.Pp
Top-level entries in the tree identify top-level PCI buses.
Each bus is named as a partial PCI selector:
.Li pci Ns Va domain Ns \&: Ns Va bus Ns .
.Pp
If the
.Fl v
flag is specified,
the device name or PCI selector is followed by the device's vendor and device
strings from the vendor/device information database.
If an identification string is not found in the database,
the ID register values are output instead.
If the option is specified twice, the vendor, device, subvendor, and
subdevice IDs are displayed in addition to the found strings.
.Ss Device Information Modes
With the
.Fl a
flag,
.Nm
determines whether any driver has been assigned to the device
identified by
.Ar selector .
An exit status of zero indicates that the device has a driver;
non-zero indicates that it does not.
.Pp
The
.Fl r
option reads a configuration space register at byte offset
.Ar addr
of device
.Ar selector
and prints out its value in hexadecimal.
The optional second address
.Ar addr2
specifies a range to read.
The
.Fl w
option writes the
.Ar value
into a configuration space register at byte offset
.Ar addr
of device
.Ar selector .
.Pp
The
.Fl D
option requests a dump of the BAR specified by its offset in config space
.Ar bar .
Dump is performed to the standard output, raw register values
are written.
Use
.Xr hexdump 1
to convert them to human-readable dump,
or redirect into a file to save the snapshot of the device state.
Optionally, the
.Ar start
and
.Ar count
of the registers dumped can be specified, in multiple of the operation width,
see below.
.Pp
The
.Fl R
option reads from the BAR specified by its offset in config space
.Ar bar .
It starts reading at byte offset
.Ar start .
The optional last argument
.Ar end
specifies a range to read.
The
.Fl W
option writes the
.Ar value
to the BAR at byte offset
.Ar offset .
.Pp
For read, write, BAR dump, BAR read, and BAR write operations, the flags
.Fl b ,
.Fl h ,
and
.Fl x
select the width of the operation;
.Fl b
indicates a byte operation, and
.Fl h
indicates a halfword (two-byte) operation.
.Fl x
indicates a quadword (four-byte) operation.
The default is to read or
write a longword (four bytes).
The quadword mode is only valid for BAR dump, BAR read, and BAR write.
.Sh ENVIRONMENT
PCI vendor and device information is read from
.Pa /usr/local/share/pciids/pci.ids .
If that file is not present, it is read from
.Pa /usr/share/misc/pci_vendors .
This path can be overridden by setting the environment variable
.Ev PCICONF_VENDOR_DATABASE .
.Sh SEE ALSO
.Xr ioctl 2 ,
.\" .Xr pci 4 ,
.Xr devinfo 8 ,
.Xr kldload 8
.Sh HISTORY
The
.Nm
utility appeared first in
.Fx 2.2 .
The
.Fl a
option was added for
.Tn PCI
KLD support in
.Fx 3.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
utility was written by
.An Stefan Esser
and
.An Garrett Wollman .
.Sh BUGS
The
.Fl b
and
.Fl h
options are implemented in
.Nm ,
but not in the underlying
.Xr ioctl 2 .
.Pp
It might be useful to give non-root users access to the
.Fl a
and
.Fl r
options.
But only root will be able to execute a
.Nm kldload
to provide the device with a driver KLD, and reading of configuration space
registers may cause a failure in badly designed
.Tn PCI
chips.
.Pp
There is currently no way to specify the caching mode for the mapping
established by the
.Fl D
option,
.Nm
always uses uncached access.
This is fine for control register BARs.