1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
|
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
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:
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"
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.
|
