setpci(8)

💖 setpci — the PCI utilities girlies' guide 💖

okay bestie, so this is setpci, from the PCI Utilities family, and she's the one you call when you want to configure PCI devices. Her sister lspci is the one who just tells you what's there; setpci is the one who actually touches the registers. main character energy, no cap. ✨

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✨ NAME ✨

setpci — configure PCI devices 🎀

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🌸 SYNOPSIS 🌸

setpci [options] devices operations...

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🦋 DESCRIPTION 🦋

setpci is a utility for querying and configuring PCI devices. That's it, that's the whole job, and she does it flawlessly. 💅

All numbers are entered in hexadecimal notation. yes, all of them. every single one. do not come at her with your decimal nonsense, she will not hear it.

Root privileges are necessary for almost all operations, excluding reads of the standard header of the configuration space on some operating systems. So like... you might get away with a read of the standard header without sudo on some OSes, but don't count on it, bestie. Please see lspci(8) for details on access rights. 👑

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💅 OPTIONS 💅

🎀 General options 🎀

• -v — Tells setpci to be verbose and display detailed information about configuration space accesses. she will tell you everything, she's an oversharer and we love her for it.
• -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. basically: quiet down girl, it's not that deep. 🤫
• -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. dry run, bestie, dry run! always demo before you commit, that's the rule. 🙈
• -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. speed vs. vibes — pick your fighter. 🏃‍♀️
• --version — Show setpci version. This option should be used stand-alone. like, don't pair her with anything else, she's a solo act.
• --help — Show detailed help on available options. This option should be used stand-alone too. one at a time, bestie.
• --dumpregs — Show a list of all known PCI registers and capabilities. This option should be used stand-alone. this one is lowkey iconic, you'll want it for the operations section below 👇

🌈 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. girl help! literally, that's the command.
• -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. tweak the settings, it's giving ✨customization✨
• -H1 — Use direct hardware access via Intel configuration mechanism 1. (This is a shorthand for -A intel-conf1.) short queen behavior.
• -H2 — Use direct hardware access via Intel configuration mechanism 2. (This is a shorthand for -A intel-conf2.) the sequel. 🎬
• -G — Increase debug level of the library. more tea, more logs, more everything. 🍓

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👑 DEVICE SELECTION 👑

Before each sequence of operations you need to select which devices you wish that operation to affect. can't just go writing to random devices, that's not the vibe.

• -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 IDs 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". wildcards go crazy here 🦋

When -s and -d are combined, only devices that match both criteria are selected. When the same option is used multiple times, the rightmost one overrides the others and a warning is produced. last one wins, and she WILL tell you about it. ⚠️

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🔥 OPERATIONS 🔥

There are two kinds of operations: reads and writes.

To read a register, just specify its name. Simple. Elegant. Ate.

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). selective editing, we love a targeted queen 💖

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. she's flexible like that. 💁‍♀️
• 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. no width? no problem, she already knows. ✨
• Finally, if a capability exists multiple times you can choose which one to target using @number. Indexing starts at 0. zero-indexed, as all good things are. 🙏

All names of registers and width specifiers are case-insensitive. command, COMMAND, CoMmAnD — all the same to her. 💅

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⭐ EXAMPLES ⭐

okay here's where it gets fun, let's go through them one by one:

• 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). little-endian girlies rise up 🧚
• 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.

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💜 SEE ALSO 💜

lspci(8), pcilib(7) — go read the sisters too, they're all connected, iykyk. 🫶

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🌸 AUTHOR 🌸

The PCI Utilities are maintained by Martin Mares <mj@ucw.cz>. thank you for your service, king 👑

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okay that's the whole page bestie, you're fully caught up, go configure something responsibly (or use -D first, seriously, use -D first) 💖✨🎀🦋🌸💅🫶

this has been pciutils-3.15.0, dated 05 April 2026 — mwah, love u, bye! 💕