Xe Configfs

Overview

Configfs is a filesystem-based manager of kernel objects. XE KMD registers a configfs subsystem called 'xe' that creates a directory in the mounted configfs directory The user can create devices under this directory and configure them as necessary See Configfs - Userspace-driven Kernel Object Configuration for more information about how configfs works.

Create devices

In order to create a device, the user has to create a directory inside 'xe':

mkdir /sys/kernel/config/xe/0000:03:00.0/

Every device created is populated by the driver with entries that can be used to configure it:

/sys/kernel/config/xe/
        .. 0000:03:00.0/
                ... survivability_mode

Configure Attributes

Survivability mode:

Enable survivability mode on supported cards. This setting only takes effect when probing the device. Example to enable it:

# echo 1 > /sys/kernel/config/xe/0000:03:00.0/survivability_mode
# echo 0000:03:00.0 > /sys/bus/pci/drivers/xe/bind  (Enters survivability mode if supported)

Allowed engines:

Allow only a set of engine(s) to be available, disabling the other engines even if they are available in hardware. This is applied after HW fuses are considered on each tile. Examples:

Allow only one render and one copy engines, nothing else:

# echo 'rcs0,bcs0' > /sys/kernel/config/xe/0000:03:00.0/engines_allowed

Allow only compute engines and first copy engine:

# echo 'ccs*,bcs0' > /sys/kernel/config/xe/0000:03:00.0/engines_allowed

Note that the engine names are the per-GT hardware names. On multi-tile platforms, writing rcs0,bcs0 to this file would allow the first render and copy engines on each tile.

The requested configuration may not be supported by the platform and driver may fail to probe. For example: if at least one copy engine is expected to be available for migrations, but it’s disabled. This is intended for debugging purposes only.

Remove devices

The created device directories can be removed using rmdir:

rmdir /sys/kernel/config/xe/0000:03:00.0/

Internal API

bool xe_configfs_get_survivability_mode(struct pci_dev *pdev)

get configfs survivability mode attribute

Parameters

struct pci_dev *pdev

pci device

Description

find the configfs group that belongs to the pci device and return the survivability mode attribute

Return

survivability mode if config group is found, false otherwise

void xe_configfs_clear_survivability_mode(struct pci_dev *pdev)

clear configfs survivability mode attribute

Parameters

struct pci_dev *pdev

pci device

Description

find the configfs group that belongs to the pci device and clear survivability mode attribute

u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev)

get engine allowed mask from configfs

Parameters

struct pci_dev *pdev

pci device

Description

Find the configfs group that belongs to the pci device and return the mask of engines allowed to be used.

Return

engine mask with allowed engines