1 What: /sys/class/firmware-attributes/*/attributes/*/
4 Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
5 Mario Limonciello <mario.limonciello@dell.com>,
6 Prasanth KSR <prasanth.ksr@dell.com>
8 A sysfs interface for systems management software to enable
9 configuration capability on supported systems. This directory
10 exposes interfaces for interacting with configuration options.
12 Unless otherwise specified in an attribute description all attributes are optional
13 and will accept UTF-8 input.
16 A file that can be read to obtain the type of attribute.
17 This attribute is mandatory.
19 The following are known types:
21 - enumeration: a set of pre-defined valid values
22 - integer: a range of numerical values
25 All attribute types support the following values:
28 A file that can be read to obtain the current
31 This file can also be written to in order to update the value of a
34 This attribute is mandatory.
37 A file that can be read to obtain the default
41 A file that can be read to obtain a user friendly
42 description of the at <attr>
44 display_name_language_code:
45 A file that can be read to obtain
46 the IETF language tag corresponding to the
47 "display_name" of the <attr>
49 "enumeration"-type specific properties:
52 A file that can be read to obtain the possible
53 values of the <attr>. Values are separated using
56 "integer"-type specific properties:
59 A file that can be read to obtain the lower
60 bound value of the <attr>
63 A file that can be read to obtain the upper
64 bound value of the <attr>
67 A file that can be read to obtain the scalar value used for
68 increments of current_value this attribute accepts.
70 "string"-type specific properties:
73 A file that can be read to obtain the maximum
74 length value of the <attr>
77 A file that can be read to obtain the minimum
78 length value of the <attr>
80 Dell specific class extensions
81 ------------------------------
83 On Dell systems the following additional attributes are available:
86 A file that can be read to obtain attribute-level
87 dependency rule. It says an attribute X will become read-only or
88 suppressed, if/if-not attribute Y is configured.
90 modifier rules can be in following format::
92 [ReadOnlyIf:<attribute>=<value>]
93 [ReadOnlyIfNot:<attribute>=<value>]
94 [SuppressIf:<attribute>=<value>]
95 [SuppressIfNot:<attribute>=<value>]
99 AutoOnFri/dell_modifier has value,
100 [SuppressIfNot:AutoOn=SelectDays]
102 This means AutoOnFri will be suppressed in BIOS setup if AutoOn
103 attribute is not "SelectDays" and its value will not be effective
104 through sysfs until this rule is met.
106 Enumeration attributes also support the following:
109 A file that can be read to obtain value-level dependency.
110 This file is similar to dell_modifier but here, an
111 attribute's current value will be forcefully changed based
112 dependent attributes value.
114 dell_value_modifier rules can be in following format::
116 <value>[ForceIf:<attribute>=<value>]
117 <value>[ForceIfNot:<attribute>=<value>]
121 LegacyOrom/dell_value_modifier has value:
122 Disabled[ForceIf:SecureBoot=Enabled]
124 This means LegacyOrom's current value will be forced to
125 "Disabled" in BIOS setup if SecureBoot is Enabled and its
126 value will not be effective through sysfs until this rule is
129 What: /sys/class/firmware-attributes/*/authentication/
132 Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
133 Mario Limonciello <mario.limonciello@dell.com>,
134 Prasanth KSR <prasanth.ksr@dell.com>
136 Devices support various authentication mechanisms which can be exposed
137 as a separate configuration object.
139 For example a "BIOS Admin" password and "System" Password can be set,
140 reset or cleared using these attributes.
142 - An "Admin" password is used for preventing modification to the BIOS
144 - A "System" password is required to boot a machine.
146 Change in any of these two authentication methods will also generate an
150 A file that can be read to obtain a 0/1 flag to see if
151 <attr> authentication is enabled.
152 This attribute is mandatory.
155 The type of authentication used.
156 This attribute is mandatory.
160 Representing BIOS administrator password
162 Representing a password required to use
166 The means of authentication. This attribute is mandatory.
167 Only supported type currently is "password".
170 A file that can be read to obtain the
171 maximum length of the Password
174 A file that can be read to obtain the
175 minimum length of the Password
178 A write only value used for privileged access such as
179 setting attributes when a system or admin password is set
180 or resetting to a new password
182 This attribute is mandatory when mechanism == "password".
185 A write only value that when used in tandem with
186 current_password will reset a system or admin password.
188 Note, password management is session specific. If Admin password is set,
189 same password must be written into current_password file (required for
190 password-validation) and must be cleared once the session is over.
193 echo "password" > current_password
194 echo "disabled" > TouchScreen/current_value
195 echo "" > current_password
197 Drivers may emit a CHANGE uevent when a password is set or unset
198 userspace may check it again.
200 On Dell and Lenovo systems, if Admin password is set, then all BIOS attributes
201 require password validation.
202 On Lenovo systems if you change the Admin password the new password is not active until
205 Lenovo specific class extensions
206 ------------------------------
208 On Lenovo systems the following additional settings are available:
211 The encoding method that is used. This can be either "ascii"
212 or "scancode". Default is set to "ascii"
215 The keyboard language method that is used. This is generally a
216 two char code (e.g. "us", "fr", "gr") and may vary per platform.
217 Default is set to "us"
219 What: /sys/class/firmware-attributes/*/attributes/pending_reboot
222 Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
223 Mario Limonciello <mario.limonciello@dell.com>,
224 Prasanth KSR <prasanth.ksr@dell.com>
226 A read-only attribute reads 1 if a reboot is necessary to apply
227 pending BIOS attribute changes. Also, an uevent_KOBJ_CHANGE is
228 generated when it changes to 1.
230 == =========================================
231 0 All BIOS attributes setting are current
232 1 A reboot is necessary to get pending BIOS
233 attribute changes applied
234 == =========================================
236 Note, userspace applications need to follow below steps for efficient
239 1. Check if admin password is set. If yes, follow session method for
240 password management as briefed under authentication section above.
241 2. Before setting any attribute, check if it has any modifiers
242 or value_modifiers. If yes, incorporate them and then modify
245 Drivers may emit a CHANGE uevent when this value changes and userspace
248 What: /sys/class/firmware-attributes/*/attributes/reset_bios
251 Contact: Divya Bharathi <Divya.Bharathi@Dell.com>,
252 Mario Limonciello <mario.limonciello@dell.com>,
253 Prasanth KSR <prasanth.ksr@dell.com>
255 This attribute can be used to reset the BIOS Configuration.
256 Specifically, it tells which type of reset BIOS configuration is being
257 requested on the host.
259 Reading from it returns a list of supported options encoded as:
261 - 'builtinsafe' (Built in safe configuration profile)
262 - 'lastknowngood' (Last known good saved configuration profile)
263 - 'factory' (Default factory settings configuration profile)
264 - 'custom' (Custom saved configuration profile)
266 The currently selected option is printed in square brackets as
269 # echo "factory" > /sys/class/firmware-attributes/*/device/attributes/reset_bios
270 # cat /sys/class/firmware-attributes/*/device/attributes/reset_bios
271 # builtinsafe lastknowngood [factory] custom
273 Note that any changes to this attribute requires a reboot
274 for changes to take effect.