What: /sys/bus/pci/drivers/.../bind What: /sys/devices/pciX/.../bind Date: December 2003 Contact: linux-pci@vger.kernel.org Description: Writing a device location to this file will cause the driver to attempt to bind to the device found at this location. This is useful for overriding default bindings. The format for the location is: DDDD:BB:DD.F. That is Domain:Bus:Device.Function and is the same as found in /sys/bus/pci/devices/. For example:: # echo 0000:00:19.0 > /sys/bus/pci/drivers/foo/bind (Note: kernels before 2.6.28 may require echo -n). What: /sys/bus/pci/drivers/.../unbind What: /sys/devices/pciX/.../unbind Date: December 2003 Contact: linux-pci@vger.kernel.org Description: Writing a device location to this file will cause the driver to attempt to unbind from the device found at this location. This may be useful when overriding default bindings. The format for the location is: DDDD:BB:DD.F. That is Domain:Bus:Device.Function and is the same as found in /sys/bus/pci/devices/. For example:: # echo 0000:00:19.0 > /sys/bus/pci/drivers/foo/unbind (Note: kernels before 2.6.28 may require echo -n). What: /sys/bus/pci/drivers/.../new_id What: /sys/devices/pciX/.../new_id Date: December 2003 Contact: linux-pci@vger.kernel.org Description: Writing a device ID to this file will attempt to dynamically add a new device ID to a PCI device driver. This may allow the driver to support more hardware than was included in the driver's static device ID support table at compile time. The format for the device ID is: VVVV DDDD SVVV SDDD CCCC MMMM PPPP. That is Vendor ID, Device ID, Subsystem Vendor ID, Subsystem Device ID, Class, Class Mask, and Private Driver Data. The Vendor ID and Device ID fields are required, the rest are optional. Upon successfully adding an ID, the driver will probe for the device and attempt to bind to it. For example:: # echo "8086 10f5" > /sys/bus/pci/drivers/foo/new_id What: /sys/bus/pci/drivers/.../remove_id What: /sys/devices/pciX/.../remove_id Date: February 2009 Contact: Chris Wright Description: Writing a device ID to this file will remove an ID that was dynamically added via the new_id sysfs entry. The format for the device ID is: VVVV DDDD SVVV SDDD CCCC MMMM. That is Vendor ID, Device ID, Subsystem Vendor ID, Subsystem Device ID, Class, and Class Mask. The Vendor ID and Device ID fields are required, the rest are optional. After successfully removing an ID, the driver will no longer support the device. This is useful to ensure auto probing won't match the driver to the device. For example:: # echo "8086 10f5" > /sys/bus/pci/drivers/foo/remove_id What: /sys/bus/pci/rescan Date: January 2009 Contact: Linux PCI developers Description: Writing a non-zero value to this attribute will force a rescan of all PCI buses in the system, and re-discover previously removed devices. What: /sys/bus/pci/devices/.../msi_bus Date: September 2014 Contact: Linux PCI developers Description: Writing a zero value to this attribute disallows MSI and MSI-X for any future drivers of the device. If the device is a bridge, MSI and MSI-X will be disallowed for future drivers of all child devices under the bridge. Drivers must be reloaded for the new setting to take effect. What: /sys/bus/pci/devices/.../msi_irqs/ Date: September, 2011 Contact: Neil Horman Description: The /sys/devices/.../msi_irqs directory contains a variable set of files, with each file being named after a corresponding msi irq vector allocated to that device. What: /sys/bus/pci/devices/.../msi_irqs/ Date: September 2011 Contact: Neil Horman Description: This attribute indicates the mode that the irq vector named by the file is in (msi vs. msix) What: /sys/bus/pci/devices/.../irq Date: August 2021 Contact: Linux PCI developers Description: If a driver has enabled MSI (not MSI-X), "irq" contains the IRQ of the first MSI vector. Otherwise "irq" contains the IRQ of the legacy INTx interrupt. "irq" being set to 0 indicates that the device isn't capable of generating legacy INTx interrupts. What: /sys/bus/pci/devices/.../remove Date: January 2009 Contact: Linux PCI developers Description: Writing a non-zero value to this attribute will hot-remove the PCI device and any of its children. What: /sys/bus/pci/devices/.../pci_bus/.../rescan Date: May 2011 Contact: Linux PCI developers Description: Writing a non-zero value to this attribute will force a rescan of the bus and all child buses, and re-discover devices removed earlier from this part of the device tree. What: /sys/bus/pci/devices/.../rescan Date: January 2009 Contact: Linux PCI developers Description: Writing a non-zero value to this attribute will force a rescan of the device's parent bus and all child buses, and re-discover devices removed earlier from this part of the device tree. What: /sys/bus/pci/devices/.../reset_method Date: August 2021 Contact: Amey Narkhede Description: Some devices allow an individual function to be reset without affecting other functions in the same slot. For devices that have this support, a file named reset_method is present in sysfs. Reading this file gives names of the supported and enabled reset methods and their ordering. Writing a space-separated list of names of reset methods sets the reset methods and ordering to be used when resetting the device. Writing an empty string disables the ability to reset the device. Writing "default" enables all supported reset methods in the default ordering. What: /sys/bus/pci/devices/.../reset Date: July 2009 Contact: Michael S. Tsirkin Description: Some devices allow an individual function to be reset without affecting other functions in the same device. For devices that have this support, a file named reset will be present in sysfs. Writing 1 to this file will perform reset. What: /sys/bus/pci/devices/.../reset_subordinate Date: October 2024 Contact: linux-pci@vger.kernel.org Description: This is visible only for bridge devices. If you want to reset all devices attached through the subordinate bus of a specific bridge device, writing 1 to this will try to do it. This will affect all devices attached to the system through this bridge similiar to writing 1 to their individual "reset" file, so use with caution. What: /sys/bus/pci/devices/.../vpd Date: February 2008 Contact: Ben Hutchings Description: A file named vpd in a device directory will be a binary file containing the Vital Product Data for the device. It should follow the VPD format defined in PCI Specification 2.1 or 2.2, but users should consider that some devices may have incorrectly formatted data. If the underlying VPD has a writable section then the corresponding section of this file will be writable. What: /sys/bus/pci/devices/.../virtfn Date: March 2009 Contact: Yu Zhao Description: This symbolic link appears when hardware supports the SR-IOV capability and the Physical Function driver has enabled it. The symbolic link points to the PCI device sysfs entry of the Virtual Function whose index is N (0...MaxVFs-1). What: /sys/bus/pci/devices/.../dep_link Date: March 2009 Contact: Yu Zhao Description: This symbolic link appears when hardware supports the SR-IOV capability and the Physical Function driver has enabled it, and this device has vendor specific dependencies with others. The symbolic link points to the PCI device sysfs entry of Physical Function this device depends on. What: /sys/bus/pci/devices/.../physfn Date: March 2009 Contact: Yu Zhao Description: This symbolic link appears when a device is a Virtual Function. The symbolic link points to the PCI device sysfs entry of the Physical Function this device associates with. What: /sys/bus/pci/devices/.../modalias Date: May 2005 Contact: Greg Kroah-Hartman Description: This attribute indicates the PCI ID of the device object. That is in the format: pci:vXXXXXXXXdXXXXXXXXsvXXXXXXXXsdXXXXXXXXbcXXscXXiXX, where: - vXXXXXXXX contains the vendor ID; - dXXXXXXXX contains the device ID; - svXXXXXXXX contains the sub-vendor ID; - sdXXXXXXXX contains the subsystem device ID; - bcXX contains the device class; - scXX contains the device subclass; - iXX contains the device class programming interface. What: /sys/bus/pci/slots/.../module Date: June 2009 Contact: linux-pci@vger.kernel.org Description: This symbolic link points to the PCI hotplug controller driver module that manages the hotplug slot. What: /sys/bus/pci/devices/.../label Date: July 2010 Contact: Narendra K , linux-bugs@dell.com Description: Reading this attribute will provide the firmware given name (SMBIOS type 41 string or ACPI _DSM string) of the PCI device. The attribute will be created only if the firmware has given a name to the PCI device. ACPI _DSM string name will be given priority if the system firmware provides SMBIOS type 41 string also. Users: Userspace applications interested in knowing the firmware assigned name of the PCI device. What: /sys/bus/pci/devices/.../index Date: July 2010 Contact: Narendra K , linux-bugs@dell.com Description: Reading this attribute will provide the firmware given instance number of the PCI device. Depending on the platform this can be for example the SMBIOS type 41 device type instance or the user-defined ID (UID) on s390. The attribute will be created only if the firmware has given an instance number to the PCI device and that number is guaranteed to uniquely identify the device in the system. Users: Userspace applications interested in knowing the firmware assigned device type instance of the PCI device that can help in understanding the firmware intended order of the PCI device. What: /sys/bus/pci/devices/.../acpi_index Date: July 2010 Contact: Narendra K , linux-bugs@dell.com Description: Reading this attribute will provide the firmware given instance (ACPI _DSM instance number) of the PCI device. The attribute will be created only if the firmware has given an instance number to the PCI device. ACPI _DSM instance number will be given priority if the system firmware provides SMBIOS type 41 device type instance also. Users: Userspace applications interested in knowing the firmware assigned instance number of the PCI device that can help in understanding the firmware intended order of the PCI device. What: /sys/bus/pci/devices/.../d3cold_allowed Date: July 2012 Contact: Huang Ying Description: d3cold_allowed is bit to control whether the corresponding PCI device can be put into D3Cold state. If it is cleared, the device will never be put into D3Cold state. If it is set, the device may be put into D3Cold state if other requirements are satisfied too. Reading this attribute will show the current value of d3cold_allowed bit. Writing this attribute will set the value of d3cold_allowed bit. What: /sys/bus/pci/devices/.../sriov_totalvfs Date: November 2012 Contact: Donald Dutile Description: This file appears when a physical PCIe device supports SR-IOV. Userspace applications can read this file to determine the maximum number of Virtual Functions (VFs) a PCIe physical function (PF) can support. Typically, this is the value reported in the PF's SR-IOV extended capability structure's TotalVFs element. Drivers have the ability at probe time to reduce the value read from this file via the pci_sriov_set_totalvfs() function. What: /sys/bus/pci/devices/.../sriov_numvfs Date: November 2012 Contact: Donald Dutile Description: This file appears when a physical PCIe device supports SR-IOV. Userspace applications can read and write to this file to determine and control the enablement or disablement of Virtual Functions (VFs) on the physical function (PF). A read of this file will return the number of VFs that are enabled on this PF. A number written to this file will enable the specified number of VFs. A userspace application would typically read the file and check that the value is zero, and then write the number of VFs that should be enabled on the PF; the value written should be less than or equal to the value in the sriov_totalvfs file. A userspace application wanting to disable the VFs would write a zero to this file. The core ensures that valid values are written to this file, and returns errors when values are not valid. For example, writing a 2 to this file when sriov_numvfs is not 0 and not 2 already will return an error. Writing a 10 when the value of sriov_totalvfs is 8 will return an error. What: /sys/bus/pci/devices/.../driver_override Date: April 2014 Contact: Alex Williamson Description: This file allows the driver for a device to be specified which will override standard static and dynamic ID matching. When specified, only a driver with a name matching the value written to driver_override will have an opportunity to bind to the device. The override is specified by writing a string to the driver_override file (echo pci-stub > driver_override) and may be cleared with an empty string (echo > driver_override). This returns the device to standard matching rules binding. Writing to driver_override does not automatically unbind the device from its current driver or make any attempt to automatically load the specified driver. If no driver with a matching name is currently loaded in the kernel, the device will not bind to any driver. This also allows devices to opt-out of driver binding using a driver_override name such as "none". Only a single driver may be specified in the override, there is no support for parsing delimiters. What: /sys/bus/pci/devices/.../numa_node Date: Oct 2014 Contact: Prarit Bhargava Description: This file contains the NUMA node to which the PCI device is attached, or -1 if the node is unknown. The initial value comes from an ACPI _PXM method or a similar firmware source. If that is missing or incorrect, this file can be written to override the node. In that case, please report a firmware bug to the system vendor. Writing to this file taints the kernel with TAINT_FIRMWARE_WORKAROUND, which reduces the supportability of your system. What: /sys/bus/pci/devices/.../revision Date: November 2016 Contact: Emil Velikov Description: This file contains the revision field of the PCI device. The value comes from device config space. The file is read only. What: /sys/bus/pci/devices/.../sriov_drivers_autoprobe Date: April 2017 Contact: Bodong Wang Description: This file is associated with the PF of a device that supports SR-IOV. It determines whether newly-enabled VFs are immediately bound to a driver. It initially contains 1, which means the kernel automatically binds VFs to a compatible driver immediately after they are enabled. If an application writes 0 to the file before enabling VFs, the kernel will not bind VFs to a driver. A typical use case is to write 0 to this file, then enable VFs, then assign the newly-created VFs to virtual machines. Note that changing this file does not affect already- enabled VFs. In this scenario, the user must first disable the VFs, write 0 to sriov_drivers_autoprobe, then re-enable the VFs. This is similar to /sys/bus/pci/drivers_autoprobe, but affects only the VFs associated with a specific PF. What: /sys/bus/pci/devices/.../p2pmem/size Date: November 2017 Contact: Logan Gunthorpe Description: If the device has any Peer-to-Peer memory registered, this file contains the total amount of memory that the device provides (in decimal). What: /sys/bus/pci/devices/.../p2pmem/available Date: November 2017 Contact: Logan Gunthorpe Description: If the device has any Peer-to-Peer memory registered, this file contains the amount of memory that has not been allocated (in decimal). What: /sys/bus/pci/devices/.../p2pmem/published Date: November 2017 Contact: Logan Gunthorpe Description: If the device has any Peer-to-Peer memory registered, this file contains a '1' if the memory has been published for use outside the driver that owns the device. What: /sys/bus/pci/devices/.../p2pmem/allocate Date: August 2022 Contact: Logan Gunthorpe Description: This file allows mapping p2pmem into userspace. For each mmap() call on this file, the kernel will allocate a chunk of Peer-to-Peer memory for use in Peer-to-Peer transactions. This memory can be used in O_DIRECT calls to NVMe backed files for Peer-to-Peer copies. What: /sys/bus/pci/devices/.../link/clkpm /sys/bus/pci/devices/.../link/l0s_aspm /sys/bus/pci/devices/.../link/l1_aspm /sys/bus/pci/devices/.../link/l1_1_aspm /sys/bus/pci/devices/.../link/l1_2_aspm /sys/bus/pci/devices/.../link/l1_1_pcipm /sys/bus/pci/devices/.../link/l1_2_pcipm Date: October 2019 Contact: Heiner Kallweit Description: If ASPM is supported for an endpoint, these files can be used to disable or enable the individual power management states. Write y/1/on to enable, n/0/off to disable. What: /sys/bus/pci/devices/.../power_state Date: November 2020 Contact: Linux PCI developers Description: This file contains the current PCI power state of the device. The value comes from the PCI kernel device state and can be one of: "unknown", "error", "D0", D1", "D2", "D3hot", "D3cold". The file is read only. What: /sys/bus/pci/devices/.../sriov_vf_total_msix Date: January 2021 Contact: Leon Romanovsky Description: This file is associated with a SR-IOV physical function (PF). It contains the total number of MSI-X vectors available for assignment to all virtual functions (VFs) associated with PF. The value will be zero if the device doesn't support this functionality. For supported devices, the value will be constant and won't be changed after MSI-X vectors assignment. What: /sys/bus/pci/devices/.../sriov_vf_msix_count Date: January 2021 Contact: Leon Romanovsky Description: This file is associated with a SR-IOV virtual function (VF). It allows configuration of the number of MSI-X vectors for the VF. This allows devices that have a global pool of MSI-X vectors to optimally divide them between VFs based on VF usage. The values accepted are: * > 0 - this number will be reported as the Table Size in the VF's MSI-X capability * < 0 - not valid * = 0 - will reset to the device default value The file is writable if the PF is bound to a driver that implements ->sriov_set_msix_vec_count(). What: /sys/bus/pci/devices/.../resourceN_resize Date: September 2022 Contact: Alex Williamson Description: These files provide an interface to PCIe Resizable BAR support. A file is created for each BAR resource (N) supported by the PCIe Resizable BAR extended capability of the device. Reading each file exposes the bitmap of available resource sizes: # cat resource1_resize 00000000000001c0 The bitmap represents supported resource sizes for the BAR, where bit0 = 1MB, bit1 = 2MB, bit2 = 4MB, etc. In the above example the device supports 64MB, 128MB, and 256MB BAR sizes. When writing the file, the user provides the bit position of the desired resource size, for example: # echo 7 > resource1_resize This indicates to set the size value corresponding to bit 7, 128MB. The resulting size is 2 ^ (bit# + 20). This definition matches the PCIe specification of this capability. In order to make use of resource resizing, all PCI drivers must be unbound from the device and peer devices under the same parent bridge may need to be soft removed. In the case of VGA devices, writing a resize value will remove low level console drivers from the device. Raw users of pci-sysfs resourceN attributes must be terminated prior to resizing. Success of the resizing operation is not guaranteed. What: /sys/bus/pci/devices/.../leds/*:enclosure:*/brightness What: /sys/class/leds/*:enclosure:*/brightness Date: August 2024 KernelVersion: 6.12 Description: LED indications on PCIe storage enclosures which are controlled through the NPEM interface (Native PCIe Enclosure Management, PCIe r6.1 sec 6.28) are accessible as led class devices, both below /sys/class/leds and below NPEM-capable PCI devices. Although these led class devices could be manipulated manually, in practice they are typically manipulated automatically by an application such as ledmon(8). The name of a led class device is as follows: :enclosure: where: - is the domain, bus, device and function number (e.g. 10000:02:05.0) - is a short description of the LED indication Valid indications per PCIe r6.1 table 6-27 are: - ok (drive is functioning normally) - locate (drive is being identified by an admin) - fail (drive is not functioning properly) - rebuild (drive is part of an array that is rebuilding) - pfa (drive is predicted to fail soon) - hotspare (drive is marked to be used as a replacement) - ica (drive is part of an array that is degraded) - ifa (drive is part of an array that is failed) - idt (drive is not the right type for the connector) - disabled (drive is disabled, removal is safe) - specific0 to specific7 (enclosure-specific indications) Broadly, the indications fall into one of these categories: - to signify drive state (ok, locate, fail, idt, disabled) - to signify drive role or state in a software RAID array (rebuild, pfa, hotspare, ica, ifa) - to signify any other role or state (specific0 to specific7) Mandatory indications per PCIe r6.1 sec 7.9.19.2 comprise: ok, locate, fail, rebuild. All others are optional. A led class device is only visible if the corresponding indication is supported by the device. To manipulate the indications, write 0 (LED_OFF) or 1 (LED_ON) to the "brightness" file. Note that manipulating an indication may implicitly manipulate other indications at the vendor's discretion. E.g. when the user lights up the "ok" indication, the vendor may choose to automatically turn off the "fail" indication. The current state of an indication can be retrieved by reading its "brightness" file. The PCIe Base Specification allows vendors leeway to choose different colors or blinking patterns for the indications, but they typically follow the IBPI standard. E.g. the "locate" indication is usually presented as one or two LEDs blinking at 4 Hz frequency: https://en.wikipedia.org/wiki/International_Blinking_Pattern_Interpretation PCI Firmware Specification r3.3 sec 4.7 defines a DSM interface to facilitate shared access by operating system and platform firmware to a device's NPEM registers. The kernel will use this DSM interface where available, instead of accessing NPEM registers directly. The DSM interface does not support the enclosure-specific indications "specific0" to "specific7", hence the corresponding led class devices are unavailable if the DSM interface is used.