openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity
linux/Documentation/ABI/testing/sysfs-bus-thunderbolt

203 lines
7.5 KiB
Plaintext
Raw Normal View History

thunderbolt: Add support for preboot ACL Preboot ACL is a mechanism that allows connecting Thunderbolt devices boot time in more secure way than the legacy Thunderbolt boot support. As with the legacy boot option, this also needs to be enabled from the BIOS before booting is allowed. Difference to the legacy mode is that the userspace software explicitly adds device UUIDs by sending a special message to the ICM firmware. Only the devices listed in the boot ACL are connected automatically during the boot. This works in both "user" and "secure" security levels. We implement this in Linux by exposing a new sysfs attribute (boot_acl) below each Thunderbolt domain. The userspace software can then update the full list as needed. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
2018-01-21 18:08:04 +08:00
What: /sys/bus/thunderbolt/devices/.../domainX/boot_acl
Date: Jun 2018
KernelVersion: 4.17
Contact: thunderbolt-software@lists.01.org
Description: Holds a comma separated list of device unique_ids that
are allowed to be connected automatically during system
startup (e.g boot devices). The list always contains
maximum supported number of unique_ids where unused
entries are empty. This allows the userspace software
to determine how many entries the controller supports.
If there are multiple controllers, each controller has
its own ACL list and size may be different between the
controllers.
System BIOS may have an option "Preboot ACL" or similar
that needs to be selected before this list is taken into
consideration.
Software always updates a full list in each write.
If a device is authorized automatically during boot its
boot attribute is set to 1.
thunderbolt: Export IOMMU based DMA protection support to userspace Recent systems with Thunderbolt ports may support IOMMU natively. In practice this means that Thunderbolt connected devices are placed behind an IOMMU during the whole time it is connected (including during boot) making Thunderbolt security levels redundant. This is called Kernel DMA protection [1] by Microsoft. Some of these systems still have Thunderbolt security level set to "user" in order to support OS downgrade (the older version of the OS might not support IOMMU based DMA protection so connecting a device still relies on user approval). Export this information to userspace by introducing a new sysfs attribute (iommu_dma_protection). Based on it userspace tools can make more accurate decision whether or not authorize the connected device. In addition update Thunderbolt documentation regarding IOMMU based DMA protection. [1] https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <YehezkelShB@gmail.com>
2018-10-31 19:06:52 +08:00
What: /sys/bus/thunderbolt/devices/.../domainX/iommu_dma_protection
Date: Mar 2019
KernelVersion: 4.21
Contact: thunderbolt-software@lists.01.org
Description: This attribute tells whether the system uses IOMMU
for DMA protection. Value of 1 means IOMMU is used 0 means
it is not (DMA protection is solely based on Thunderbolt
security levels).
thunderbolt: Add support for Internal Connection Manager (ICM) Starting from Intel Falcon Ridge the internal connection manager running on the Thunderbolt host controller has been supporting 4 security levels. One reason for this is to prevent DMA attacks and only allow connecting devices the user trusts. The internal connection manager (ICM) is the preferred way of connecting Thunderbolt devices over software only implementation typically used on Macs. The driver communicates with ICM using special Thunderbolt ring 0 (control channel) messages. In order to handle these messages we add support for the ICM messages to the control channel. The security levels are as follows: none - No security, all tunnels are created automatically user - User needs to approve the device before tunnels are created secure - User need to approve the device before tunnels are created. The device is sent a challenge on future connects to be able to verify it is actually the approved device. dponly - Only Display Port and USB tunnels can be created and those are created automatically. The security levels are typically configurable from the system BIOS and by default it is set to "user" on many systems. In this patch each Thunderbolt device will have either one or two new sysfs attributes: authorized and key. The latter appears for devices that support secure connect. In order to identify the device the user can read identication information, including UUID and name of the device from sysfs and based on that make a decision to authorize the device. The device is authorized by simply writing 1 to the "authorized" sysfs attribute. This is following the USB bus device authorization mechanism. The secure connect requires an additional challenge step (writing 2 to the "authorized" attribute) in future connects when the key has already been stored to the NVM of the device. Non-ICM systems (before Alpine Ridge) continue to use the existing functionality and the security level is set to none. For systems with Alpine Ridge, even on Apple hardware, we will use ICM. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:16 +08:00
What: /sys/bus/thunderbolt/devices/.../domainX/security
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute holds current Thunderbolt security level
set by the system BIOS. Possible values are:
none: All devices are automatically authorized
user: Devices are only authorized based on writing
appropriate value to the authorized attribute
secure: Require devices that support secure connect at
minimum. User needs to authorize each device.
dponly: Automatically tunnel Display port (and USB). No
PCIe tunnels are created.
thunderbolt: Introduce USB only (SL4) security level This new security level works so that it creates one PCIe tunnel to the connected Thunderbolt dock, removing PCIe links downstream of the dock. This leaves only the internal USB controller visible. Display Port tunnels are created normally. While there make sure security sysfs attribute returns "unknown" for any future security level. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
2017-12-08 19:11:39 +08:00
usbonly: Automatically tunnel USB controller of the
connected Thunderbolt dock (and Display Port). All
PCIe links downstream of the dock are removed.
thunderbolt: Add support for Internal Connection Manager (ICM) Starting from Intel Falcon Ridge the internal connection manager running on the Thunderbolt host controller has been supporting 4 security levels. One reason for this is to prevent DMA attacks and only allow connecting devices the user trusts. The internal connection manager (ICM) is the preferred way of connecting Thunderbolt devices over software only implementation typically used on Macs. The driver communicates with ICM using special Thunderbolt ring 0 (control channel) messages. In order to handle these messages we add support for the ICM messages to the control channel. The security levels are as follows: none - No security, all tunnels are created automatically user - User needs to approve the device before tunnels are created secure - User need to approve the device before tunnels are created. The device is sent a challenge on future connects to be able to verify it is actually the approved device. dponly - Only Display Port and USB tunnels can be created and those are created automatically. The security levels are typically configurable from the system BIOS and by default it is set to "user" on many systems. In this patch each Thunderbolt device will have either one or two new sysfs attributes: authorized and key. The latter appears for devices that support secure connect. In order to identify the device the user can read identication information, including UUID and name of the device from sysfs and based on that make a decision to authorize the device. The device is authorized by simply writing 1 to the "authorized" sysfs attribute. This is following the USB bus device authorization mechanism. The secure connect requires an additional challenge step (writing 2 to the "authorized" attribute) in future connects when the key has already been stored to the NVM of the device. Non-ICM systems (before Alpine Ridge) continue to use the existing functionality and the security level is set to none. For systems with Alpine Ridge, even on Apple hardware, we will use ICM. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:16 +08:00
What: /sys/bus/thunderbolt/devices/.../authorized
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute is used to authorize Thunderbolt devices
after they have been connected. If the device is not
authorized, no devices such as PCIe and Display port are
available to the system.
Contents of this attribute will be 0 when the device is not
yet authorized.
Possible values are supported:
1: The device will be authorized and connected
When key attribute contains 32 byte hex string the possible
values are:
1: The 32 byte hex string is added to the device NVM and
the device is authorized.
2: Send a challenge based on the 32 byte hex string. If the
challenge response from device is valid, the device is
authorized. In case of failure errno will be ENOKEY if
the device did not contain a key at all, and
EKEYREJECTED if the challenge response did not match.
thunderbolt: Add 'boot' attribute for devices In various cases, Thunderbolt device can be connected by ICM on boot without waiting for approval from user. Most cases are related to OEM-specific BIOS configurations. This information is interesting for user-space as if the device isn't in SW ACL, it may create a friction in the user experience where the device is automatically authorized if it's connected on boot but requires an explicit user action if connected after OS is up. User-space can use this information to suggest adding the device to SW ACL for auto-authorization on later connections. Signed-off-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
2018-01-22 18:50:09 +08:00
What: /sys/bus/thunderbolt/devices/.../boot
Date: Jun 2018
KernelVersion: 4.17
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains 1 if Thunderbolt device was already
authorized on boot and 0 otherwise.
thunderbolt: Add support for Internal Connection Manager (ICM) Starting from Intel Falcon Ridge the internal connection manager running on the Thunderbolt host controller has been supporting 4 security levels. One reason for this is to prevent DMA attacks and only allow connecting devices the user trusts. The internal connection manager (ICM) is the preferred way of connecting Thunderbolt devices over software only implementation typically used on Macs. The driver communicates with ICM using special Thunderbolt ring 0 (control channel) messages. In order to handle these messages we add support for the ICM messages to the control channel. The security levels are as follows: none - No security, all tunnels are created automatically user - User needs to approve the device before tunnels are created secure - User need to approve the device before tunnels are created. The device is sent a challenge on future connects to be able to verify it is actually the approved device. dponly - Only Display Port and USB tunnels can be created and those are created automatically. The security levels are typically configurable from the system BIOS and by default it is set to "user" on many systems. In this patch each Thunderbolt device will have either one or two new sysfs attributes: authorized and key. The latter appears for devices that support secure connect. In order to identify the device the user can read identication information, including UUID and name of the device from sysfs and based on that make a decision to authorize the device. The device is authorized by simply writing 1 to the "authorized" sysfs attribute. This is following the USB bus device authorization mechanism. The secure connect requires an additional challenge step (writing 2 to the "authorized" attribute) in future connects when the key has already been stored to the NVM of the device. Non-ICM systems (before Alpine Ridge) continue to use the existing functionality and the security level is set to none. For systems with Alpine Ridge, even on Apple hardware, we will use ICM. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:16 +08:00
What: /sys/bus/thunderbolt/devices/.../key
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: When a devices supports Thunderbolt secure connect it will
have this attribute. Writing 32 byte hex string changes
authorization to use the secure connection method instead.
thunderbolt: Allow clearing the key If secure authentication of a devices fails, either because the device already has another key uploaded, or there is some other error sending challenge to the device, and the user only wants to approve the device just once (without a new key being uploaded to the device) the current implementation does not allow this because the key cannot be cleared once set even if we allow it to be changed. Make this scenario possible and allow clearing the key by writing empty string to the key sysfs file. Signed-off-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-08-15 13:19:20 +08:00
Writing an empty string clears the key and regular connection
method can be used again.
thunderbolt: Add support for Internal Connection Manager (ICM) Starting from Intel Falcon Ridge the internal connection manager running on the Thunderbolt host controller has been supporting 4 security levels. One reason for this is to prevent DMA attacks and only allow connecting devices the user trusts. The internal connection manager (ICM) is the preferred way of connecting Thunderbolt devices over software only implementation typically used on Macs. The driver communicates with ICM using special Thunderbolt ring 0 (control channel) messages. In order to handle these messages we add support for the ICM messages to the control channel. The security levels are as follows: none - No security, all tunnels are created automatically user - User needs to approve the device before tunnels are created secure - User need to approve the device before tunnels are created. The device is sent a challenge on future connects to be able to verify it is actually the approved device. dponly - Only Display Port and USB tunnels can be created and those are created automatically. The security levels are typically configurable from the system BIOS and by default it is set to "user" on many systems. In this patch each Thunderbolt device will have either one or two new sysfs attributes: authorized and key. The latter appears for devices that support secure connect. In order to identify the device the user can read identication information, including UUID and name of the device from sysfs and based on that make a decision to authorize the device. The device is authorized by simply writing 1 to the "authorized" sysfs attribute. This is following the USB bus device authorization mechanism. The secure connect requires an additional challenge step (writing 2 to the "authorized" attribute) in future connects when the key has already been stored to the NVM of the device. Non-ICM systems (before Alpine Ridge) continue to use the existing functionality and the security level is set to none. For systems with Alpine Ridge, even on Apple hardware, we will use ICM. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:16 +08:00
thunderbolt: Convert switch to a device Thunderbolt domain consists of switches that are connected to each other, forming a bus. This will convert each switch into a real Linux device structure and adds them to the domain. The advantage here is that we get all the goodies from the driver core, like reference counting and sysfs hierarchy for free. Also expose device identification information to the userspace via new sysfs attributes. In order to support internal connection manager (ICM) we separate switch configuration into its own function (tb_switch_configure()) which is only called by the existing native connection manager implementation used on Macs. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Michael Jamet <michael.jamet@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:01 +08:00
What: /sys/bus/thunderbolt/devices/.../device
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains id of this device extracted from
the device DROM.
thunderbolt: Read vendor and device name from DROM The device DROM contains name of the vendor and device among other things. Extract this information and expose it to the userspace via two new attributes. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:05 +08:00
What: /sys/bus/thunderbolt/devices/.../device_name
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains name of this device extracted from
the device DROM.
thunderbolt: Convert switch to a device Thunderbolt domain consists of switches that are connected to each other, forming a bus. This will convert each switch into a real Linux device structure and adds them to the domain. The advantage here is that we get all the goodies from the driver core, like reference counting and sysfs hierarchy for free. Also expose device identification information to the userspace via new sysfs attributes. In order to support internal connection manager (ICM) we separate switch configuration into its own function (tb_switch_configure()) which is only called by the existing native connection manager implementation used on Macs. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Michael Jamet <michael.jamet@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:01 +08:00
What: /sys/bus/thunderbolt/devices/.../vendor
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains vendor id of this device extracted
from the device DROM.
thunderbolt: Read vendor and device name from DROM The device DROM contains name of the vendor and device among other things. Extract this information and expose it to the userspace via two new attributes. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:05 +08:00
What: /sys/bus/thunderbolt/devices/.../vendor_name
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains vendor name of this device extracted
from the device DROM.
thunderbolt: Convert switch to a device Thunderbolt domain consists of switches that are connected to each other, forming a bus. This will convert each switch into a real Linux device structure and adds them to the domain. The advantage here is that we get all the goodies from the driver core, like reference counting and sysfs hierarchy for free. Also expose device identification information to the userspace via new sysfs attributes. In order to support internal connection manager (ICM) we separate switch configuration into its own function (tb_switch_configure()) which is only called by the existing native connection manager implementation used on Macs. Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Michael Jamet <michael.jamet@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:01 +08:00
What: /sys/bus/thunderbolt/devices/.../unique_id
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: This attribute contains unique_id string of this device.
This is either read from hardware registers (UUID on
newer hardware) or based on UID from the device DROM.
Can be used to uniquely identify particular device.
thunderbolt: Add support for host and device NVM firmware upgrade Starting from Intel Falcon Ridge the NVM firmware can be upgraded by using DMA configuration based mailbox commands. If we detect that the host or device (device support starts from Intel Alpine Ridge) has the DMA configuration based mailbox we expose NVM information to the userspace as two separate Linux NVMem devices: nvm_active and nvm_non_active. The former is read-only portion of the active NVM which firmware upgrade tools can be use to find out suitable NVM image if the device identification strings are not enough. The latter is write-only portion where the new NVM image is to be written by the userspace. It is up to the userspace to find out right NVM image (the kernel does very minimal validation). The ICM firmware itself authenticates the new NVM firmware and fails the operation if it is not what is expected. We also expose two new sysfs files per each switch: nvm_version and nvm_authenticate which can be used to read the active NVM version and start the upgrade process. We also introduce safe mode which is the mode a switch goes when it does not have properly authenticated firmware. In this mode the switch only accepts a couple of commands including flashing a new NVM firmware image and triggering power cycle. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andreas Noever <andreas.noever@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-06 20:25:17 +08:00
What: /sys/bus/thunderbolt/devices/.../nvm_version
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: If the device has upgradeable firmware the version
number is available here. Format: %x.%x, major.minor.
If the device is in safe mode reading the file returns
-ENODATA instead as the NVM version is not available.
What: /sys/bus/thunderbolt/devices/.../nvm_authenticate
Date: Sep 2017
KernelVersion: 4.13
Contact: thunderbolt-software@lists.01.org
Description: When new NVM image is written to the non-active NVM
area (through non_activeX NVMem device), the
authentication procedure is started by writing 1 to
this file. If everything goes well, the device is
restarted with the new NVM firmware. If the image
verification fails an error code is returned instead.
When read holds status of the last authentication
operation if an error occurred during the process. This
is directly the status value from the DMA configuration
based mailbox before the device is power cycled. Writing
0 here clears the status.
thunderbolt: Add support for XDomain discovery protocol When two hosts are connected over a Thunderbolt cable, there is a protocol they can use to communicate capabilities supported by the host. The discovery protocol uses automatically configured control channel (ring 0) and is build on top of request/response transactions using special XDomain primitives provided by the Thunderbolt base protocol. The capabilities consists of a root directory block of basic properties used for identification of the host, and then there can be zero or more directories each describing a Thunderbolt service and its capabilities. Once both sides have discovered what is supported the two hosts can setup high-speed DMA paths and transfer data to the other side using whatever protocol was agreed based on the properties. The software protocol used to communicate which DMA paths to enable is service specific. This patch adds support for the XDomain discovery protocol to the Thunderbolt bus. We model each remote host connection as a Linux XDomain device. For each Thunderbolt service found supported on the XDomain device, we create Linux Thunderbolt service device which Thunderbolt service drivers can then bind to based on the protocol identification information retrieved from the property directory describing the service. This code is based on the work done by Amir Levy and Michael Jamet. Signed-off-by: Michael Jamet <michael.jamet@intel.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-02 18:38:34 +08:00
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/key
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: This contains name of the property directory the XDomain
service exposes. This entry describes the protocol in
question. Following directories are already reserved by
the Apple XDomain specification:
network: IP/ethernet over Thunderbolt
targetdm: Target disk mode protocol over Thunderbolt
extdisp: External display mode protocol over Thunderbolt
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/modalias
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: Stores the same MODALIAS value emitted by uevent for
the XDomain service. Format: tbtsvc:kSpNvNrN
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcid
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: This contains XDomain protocol identifier the XDomain
service supports.
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcvers
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: This contains XDomain protocol version the XDomain
service supports.
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcrevs
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: This contains XDomain software version the XDomain
service supports.
What: /sys/bus/thunderbolt/devices/<xdomain>.<service>/prtcstns
Date: Jan 2018
KernelVersion: 4.15
Contact: thunderbolt-software@lists.01.org
Description: This contains XDomain service specific settings as
bitmask. Format: %x