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+What: /sys/class/firmware-attributes/*/attributes/*/
+Date: February 2021
+KernelVersion: 5.11
+Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
+ Prasanth KSR <prasanth.ksr@dell.com>
+ Dell.Client.Kernel@dell.com
+Description:
+ A sysfs interface for systems management software to enable
+ configuration capability on supported systems. This directory
+ exposes interfaces for interacting with configuration options.
+
+ Unless otherwise specified in an attribute description all attributes are optional
+ and will accept UTF-8 input.
+
+ type:
+ A file that can be read to obtain the type of attribute.
+ This attribute is mandatory.
+
+ The following are known types:
+
+ - enumeration: a set of pre-defined valid values
+ - integer: a range of numerical values
+ - string
+
+ All attribute types support the following values:
+
+ current_value:
+ A file that can be read to obtain the current
+ value of the <attr>.
+
+ This file can also be written to in order to update the value of a
+ <attr>
+
+ This attribute is mandatory.
+
+ default_value:
+ A file that can be read to obtain the default
+ value of the <attr>
+
+ display_name:
+ A file that can be read to obtain a user friendly
+ description of the at <attr>
+
+ display_name_language_code:
+ A file that can be read to obtain
+ the IETF language tag corresponding to the
+ "display_name" of the <attr>
+
+ "enumeration"-type specific properties:
+
+ possible_values:
+ A file that can be read to obtain the possible
+ values of the <attr>. Values are separated using
+ semi-colon (``;``).
+
+ "integer"-type specific properties:
+
+ min_value:
+ A file that can be read to obtain the lower
+ bound value of the <attr>
+
+ max_value:
+ A file that can be read to obtain the upper
+ bound value of the <attr>
+
+ scalar_increment:
+ A file that can be read to obtain the scalar value used for
+ increments of current_value this attribute accepts.
+
+ "string"-type specific properties:
+
+ max_length:
+ A file that can be read to obtain the maximum
+ length value of the <attr>
+
+ min_length:
+ A file that can be read to obtain the minimum
+ length value of the <attr>
+
+ Dell specific class extensions
+ ------------------------------
+
+ On Dell systems the following additional attributes are available:
+
+ dell_modifier:
+ A file that can be read to obtain attribute-level
+ dependency rule. It says an attribute X will become read-only or
+ suppressed, if/if-not attribute Y is configured.
+
+ modifier rules can be in following format::
+
+ [ReadOnlyIf:<attribute>=<value>]
+ [ReadOnlyIfNot:<attribute>=<value>]
+ [SuppressIf:<attribute>=<value>]
+ [SuppressIfNot:<attribute>=<value>]
+
+ For example::
+
+ AutoOnFri/dell_modifier has value,
+ [SuppressIfNot:AutoOn=SelectDays]
+
+ This means AutoOnFri will be suppressed in BIOS setup if AutoOn
+ attribute is not "SelectDays" and its value will not be effective
+ through sysfs until this rule is met.
+
+ Enumeration attributes also support the following:
+
+ dell_value_modifier:
+ A file that can be read to obtain value-level dependency.
+ This file is similar to dell_modifier but here, an
+ attribute's current value will be forcefully changed based
+ dependent attributes value.
+
+ dell_value_modifier rules can be in following format::
+
+ <value>[ForceIf:<attribute>=<value>]
+ <value>[ForceIfNot:<attribute>=<value>]
+
+ For example::
+
+ LegacyOrom/dell_value_modifier has value:
+ Disabled[ForceIf:SecureBoot=Enabled]
+
+ This means LegacyOrom's current value will be forced to
+ "Disabled" in BIOS setup if SecureBoot is Enabled and its
+ value will not be effective through sysfs until this rule is
+ met.
+
+What: /sys/class/firmware-attributes/*/authentication/
+Date: February 2021
+KernelVersion: 5.11
+Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
+ Prasanth KSR <prasanth.ksr@dell.com>
+ Dell.Client.Kernel@dell.com
+Description:
+ Devices support various authentication mechanisms which can be exposed
+ as a separate configuration object.
+
+ For example a "BIOS Admin" password and "System" Password can be set,
+ reset or cleared using these attributes.
+
+ - An "Admin" password is used for preventing modification to the BIOS
+ settings.
+ - A "System" password is required to boot a machine.
+
+ Change in any of these two authentication methods will also generate an
+ uevent KOBJ_CHANGE.
+
+ is_enabled:
+ A file that can be read to obtain a 0/1 flag to see if
+ <attr> authentication is enabled.
+ This attribute is mandatory.
+
+ role:
+ The type of authentication used.
+ This attribute is mandatory.
+
+ Known types:
+ bios-admin:
+ Representing BIOS administrator password
+ power-on:
+ Representing a password required to use
+ the system
+ system-mgmt:
+ Representing System Management password.
+ See Lenovo extensions section for details
+ HDD:
+ Representing HDD password
+ See Lenovo extensions section for details
+ NVMe:
+ Representing NVMe password
+ See Lenovo extensions section for details
+
+ mechanism:
+ The means of authentication. This attribute is mandatory.
+ Only supported type currently is "password".
+
+ max_password_length:
+ A file that can be read to obtain the
+ maximum length of the Password
+
+ min_password_length:
+ A file that can be read to obtain the
+ minimum length of the Password
+
+ current_password:
+ A write only value used for privileged access such as
+ setting attributes when a system or admin password is set
+ or resetting to a new password
+
+ This attribute is mandatory when mechanism == "password".
+
+ new_password:
+ A write only value that when used in tandem with
+ current_password will reset a system or admin password.
+
+ Note, password management is session specific. If Admin password is set,
+ same password must be written into current_password file (required for
+ password-validation) and must be cleared once the session is over.
+ For example::
+
+ echo "password" > current_password
+ echo "disabled" > TouchScreen/current_value
+ echo "" > current_password
+
+ Drivers may emit a CHANGE uevent when a password is set or unset
+ userspace may check it again.
+
+ On Dell and Lenovo systems, if Admin password is set, then all BIOS attributes
+ require password validation.
+ On Lenovo systems if you change the Admin password the new password is not active until
+ the next boot.
+
+ Lenovo specific class extensions
+ --------------------------------
+
+ On Lenovo systems the following additional settings are available:
+
+ role: system-mgmt This gives the same authority as the bios-admin password to control
+ security related features. The authorities allocated can be set via
+ the BIOS menu SMP Access Control Policy
+
+ role: HDD & NVMe This password is used to unlock access to the drive at boot. Note see
+ 'level' and 'index' extensions below.
+
+ lenovo_encoding:
+ The encoding method that is used. This can be either "ascii"
+ or "scancode". Default is set to "ascii"
+
+ lenovo_kbdlang:
+ The keyboard language method that is used. This is generally a
+ two char code (e.g. "us", "fr", "gr") and may vary per platform.
+ Default is set to "us"
+
+ level:
+ Available for HDD and NVMe authentication to set 'user' or 'master'
+ privilege level.
+ If only the user password is configured then this should be used to
+ unlock the drive at boot. If both master and user passwords are set
+ then either can be used. If a master password is set a user password
+ is required.
+ This attribute defaults to 'user' level
+
+ index:
+ Used with HDD and NVME authentication to set the drive index
+ that is being referenced (e.g hdd0, hdd1 etc)
+ This attribute defaults to device 0.
+
+ certificate, signature, save_signature:
+ These attributes are used for certificate based authentication. This is
+ used in conjunction with a signing server as an alternative to password
+ based authentication.
+ The user writes to the attribute(s) with a BASE64 encoded string obtained
+ from the signing server.
+ The attributes can be displayed to check the stored value.
+
+ Some usage examples:
+
+ Installing a certificate to enable feature::
+
+ echo "supervisor password" > authentication/Admin/current_password
+ echo "signed certificate" > authentication/Admin/certificate
+
+ Updating the installed certificate::
+
+ echo "signature" > authentication/Admin/signature
+ echo "signed certificate" > authentication/Admin/certificate
+
+ Removing the installed certificate::
+
+ echo "signature" > authentication/Admin/signature
+ echo "" > authentication/Admin/certificate
+
+ Changing a BIOS setting::
+
+ echo "signature" > authentication/Admin/signature
+ echo "save signature" > authentication/Admin/save_signature
+ echo Enable > attribute/PasswordBeep/current_value
+
+ You cannot enable certificate authentication if a supervisor password
+ has not been set.
+ Clearing the certificate results in no bios-admin authentication method
+ being configured allowing anyone to make changes.
+ After any of these operations the system must reboot for the changes to
+ take effect.
+
+ certificate_thumbprint:
+ Read only attribute used to display the MD5, SHA1 and SHA256 thumbprints
+ for the certificate installed in the BIOS.
+
+ certificate_to_password:
+ Write only attribute used to switch from certificate based authentication
+ back to password based.
+ Usage::
+
+ echo "signature" > authentication/Admin/signature
+ echo "password" > authentication/Admin/certificate_to_password
+
+
+What: /sys/class/firmware-attributes/*/attributes/pending_reboot
+Date: February 2021
+KernelVersion: 5.11
+Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
+ Prasanth KSR <prasanth.ksr@dell.com>
+ Dell.Client.Kernel@dell.com
+Description:
+ A read-only attribute reads 1 if a reboot is necessary to apply
+ pending BIOS attribute changes. Also, an uevent_KOBJ_CHANGE is
+ generated when it changes to 1.
+
+ == =========================================
+ 0 All BIOS attributes setting are current
+ 1 A reboot is necessary to get pending BIOS
+ attribute changes applied
+ == =========================================
+
+ Note, userspace applications need to follow below steps for efficient
+ BIOS management,
+
+ 1. Check if admin password is set. If yes, follow session method for
+ password management as briefed under authentication section above.
+ 2. Before setting any attribute, check if it has any modifiers
+ or value_modifiers. If yes, incorporate them and then modify
+ attribute.
+
+ Drivers may emit a CHANGE uevent when this value changes and userspace
+ may check it again.
+
+What: /sys/class/firmware-attributes/*/attributes/reset_bios
+Date: February 2021
+KernelVersion: 5.11
+Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
+ Prasanth KSR <prasanth.ksr@dell.com>
+ Dell.Client.Kernel@dell.com
+Description:
+ This attribute can be used to reset the BIOS Configuration.
+ Specifically, it tells which type of reset BIOS configuration is being
+ requested on the host.
+
+ Reading from it returns a list of supported options encoded as:
+
+ - 'builtinsafe' (Built in safe configuration profile)
+ - 'lastknowngood' (Last known good saved configuration profile)
+ - 'factory' (Default factory settings configuration profile)
+ - 'custom' (Custom saved configuration profile)
+
+ The currently selected option is printed in square brackets as
+ shown below::
+
+ # echo "factory" > /sys/class/firmware-attributes/*/device/attributes/reset_bios
+ # cat /sys/class/firmware-attributes/*/device/attributes/reset_bios
+ builtinsafe lastknowngood [factory] custom
+
+ Note that any changes to this attribute requires a reboot
+ for changes to take effect.
+
+What: /sys/class/firmware-attributes/*/attributes/debug_cmd
+Date: July 2021
+KernelVersion: 5.14
+Contact: Mark Pearson <markpearson@lenovo.com>
+Description:
+ This write only attribute can be used to send debug commands to the BIOS.
+ This should only be used when recommended by the BIOS vendor. Vendors may
+ use it to enable extra debug attributes or BIOS features for testing purposes.
+
+ Note that any changes to this attribute requires a reboot for changes to take effect.