setpci(8)		       The PCI Utilities		     setpci(8)

NAME
       setpci - configure PCI devices

SYNOPSIS
       setpci [options] devices operations...


DESCRIPTION
       setpci is a utility for querying and configuring PCI devices.

       All numbers are entered in hexadecimal notation.

       Root privileges are necessary for almost all operations, excluding
       reads of the standard header of the configuration space on some
       operating systems.  Please see lspci(8) for details on access rights.


OPTIONS
   General options
       -v     Tells setpci to be verbose and display detailed information
	      about configuration space accesses.

       -f     Tells setpci not to complain when there's nothing to do (when no
	      devices are selected).  This option is intended for use in
	      widely-distributed configuration scripts where it's uncertain
	      whether the device in question is present in the machine or not.

       -D     `Demo mode' -- don't write anything to the configuration
	      registers.  It's useful to try setpci -vD to verify that your
	      complex sequence of setpci operations does what you think it
	      should do.

       -r     Avoids bus scan if each operation selects a specific device
	      (uses the -s selector with specific domain, bus, slot, and
	      function). This is faster, but if the device does not exist, it
	      fails instead of matching an empty set of devices.

       --version
	      Show setpci version. This option should be used stand-alone.

       --help Show detailed help on available options. This option should be
	      used stand-alone.

       --dumpregs
	      Show a list of all known PCI registers and capabilities. This
	      option should be used stand-alone.


   PCI access options
       The PCI utilities use the PCI library to talk to PCI devices (see
       pcilib(7) for details). You can use the following options to influence
       its behavior:

       -A <method>
	      The library supports a variety of methods to access the PCI
	      hardware.	 By default, it uses the first access method
	      available, but you can use this option to override this
	      decision. See -A help for a list of available methods and their
	      descriptions.

       -O <param>=<value>
	      The behavior of the library is controlled by several named
	      parameters.  This option allows one to set the value of any of
	      the parameters. Use -O help for a list of known parameters and
	      their default values.

       -H1    Use direct hardware access via Intel configuration mechanism 1.
	      (This is a shorthand for -A intel-conf1.)

       -H2    Use direct hardware access via Intel configuration mechanism 2.
	      (This is a shorthand for -A intel-conf2.)

       -G     Increase debug level of the library.


DEVICE SELECTION
       Before each sequence of operations you need to select which devices you
       wish that operation to affect.

       -s [[[[<domain>]:]<bus>]:][<slot>][.[<func>]]
	      Consider only devices in the specified domain (in case your
	      machine has several host bridges, they can either share a common
	      bus number space or each of them can address a PCI domain of its
	      own; domains are numbered from 0 to ffff), bus (0 to ff), slot
	      (0 to 1f) and function (0 to 7).	Each component of the device
	      address can be omitted or set to "*", both meaning "any value".
	      All numbers are hexadecimal.  E.g., "0:" means all devices on
	      bus 0, "0" means all functions of device 0 on any bus, "0.3"
	      selects third function of device 0 on all buses and ".4" matches
	      only the fourth function of each device.

       -d [<vendor>]:[<device>][:<class>[:<prog-if>]]
	      Select devices with specified vendor, device, class ID, and
	      programming interface.  The ID's are given in hexadecimal and
	      may be omitted or given as "*", both meaning "any value". The
	      class ID can contain "x" characters which stand for "any digit".

       When -s and -d are combined, only devices that match both criteria are
       selected. When multiple options of the same kind are specified, the
       rightmost one overrides the others.


OPERATIONS
       There are two kinds of operations: reads and writes. To read a
       register, just specify its name. Writes have the form
       name=value,value... where each value is either a hexadecimal number or
       an expression of type data:mask where both data and mask are
       hexadecimal numbers. In the latter case, only the bits corresponding to
       binary ones in the mask are changed (technically, this is a read-
       modify-write operation).


       There are several ways to identify a register:

       •      Tell its address in hexadecimal.

       •      Spell its name. Setpci knows the names of all registers in the
	      standard configuration headers. Use `setpci --dumpregs' to get
	      the complete list.  See PCI bus specifications for the precise
	      meaning of these registers or consult header.h or
	      /usr/include/pci/pci.h for a brief sketch.

       •      If the register is a part of a PCI capability, you can specify
	      the name of the capability to get the address of its first
	      register. See the names starting with `CAP_' or `ECAP_' in the
	      --dumpregs output.

       •      If the name of the capability is not known to setpci, you can
	      refer to it by its number in the form CAPid or ECAPid, where id
	      is the numeric identifier of the capability in hexadecimal.

       •      Each of the previous formats can be followed by +offset to add
	      an offset (a hex number) to the address. This feature can be
	      useful for addressing of registers living within a capability,
	      or to modify parts of standard registers.

       •      To choose how many bytes (1, 2, or 4) should be transferred, you
	      should append a width specifier .B, .W, or .L. The width can be
	      omitted if you are referring to a register by its name and the
	      width of the register is well known.

       •      Finally, if a capability exists multiple times you can choose
	      which one to target using @number. Indexing starts at 0.


       All names of registers and width specifiers are case-insensitive.


EXAMPLES
       COMMAND
	      asks for the word-sized command register.

       4.w    is a numeric address of the same register.

       COMMAND.l
	      asks for a 32-bit word starting at the location of the command
	      register, i.e., the command and status registers together.

       VENDOR_ID+1.b
	      specifies the upper byte of the vendor ID register (remember,
	      PCI is little-endian).

       CAP_PM+2.w
	      corresponds to the second word of the power management
	      capability.

       ECAP108.l
	      asks for the first 32-bit word of the extended capability with
	      ID 0x108.


SEE ALSO
       lspci(8), pcilib(7)


AUTHOR
       The PCI Utilities are maintained by Martin Mares <mj@ucw.cz>.

pciutils-3.14.0			 21 June 2025			     setpci(8)