root/lm-sensors/trunk/doc/developers/proc

Revision 3000, 5.6 kB (checked in by khali, 3 years ago)

Fix common spelling errors.

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1 Naming and data format standards under /proc
2 --------------------------------------------
3
4 The libsensors library offers an interface to the raw sensors data
5 through the sysctl interface. See the doc/developers/sysctl
6 and the libsensors source for further information.
7
8 An alternative method that some programs use is to access the /proc
9 files directly. This document briefly describes the standards that
10 the drivers follow, so that an application program can scan for
11 entries and access this data in a simple and consistent way.
12
13 Note that not all chip drivers adhere to this standard.
14 We will attempt to migrate older drivers to this standard,
15 and ensure that new drivers follow this standard wherever possible.
16 If you are developing a userspace application please send us
17 feedback on this standard.
18
19 Note that motherboards vary widely in the connections to sensor chips.
20 There is no standard that ensures, for example, that the second
21 temperature sensor is connected to the CPU, or that the second
22 fan is on the CPU. Therefore, programs must provide a facility
23 for the user to label or bind /proc entries for display.
24 Sensor chips often have unused inputs that should be ignored
25 by user programs.
26
27 Each chip gets its own directory under /proc/sys/dev/sensors.
28 The format is either chip-i2c-bus-hexaddress or chip-isa-hexaddress.
29 (Exception - chip lm78-j has a '-' in it - should this be changed??)
30 New dummy drivers may present chips as chip-busname-hexaddress.
31
32 All /proc values are integers or floating point numbers.
33 There is no facility in the lm_sensors package for drivers
34 to output general strings via /proc. This facility may be added
35 in the future.
36
37 Alarms are direct indications read from the chips. The drivers do NOT make
38 comparisons of readings to thresholds. This allows violations
39 between readings to be caught and alarmed. The exact definition of
40 an alarm (for example, whether a threshold must be met or must be
41 exceeded to cause an alarm) is chip-dependent.
42
43 Guidelines for new entries:
44         - If there are multiple values, some r/w and some r/o,
45           put the r/w ones first.
46         - Additional non-standard values should be after the standard values.
47
48
49
50 -------------------------------------------------------------------------
51
52 /proc entries are as follows:
53
54
55 Entry   Values  Function
56 -----   ------  --------
57 alarms    1     Alarm bitmask.
58                 Read only.
59                 Integer representation of one to four bytes.
60                 A '1' bit means an alarm.
61                 Chips should be programmed for 'comparator' mode so that
62                 the alarm will 'come back' after you read the register
63                 if it is still valid.
64                 Generally a direct representation of a chip's internal
65                 alarm registers; there is no standard for the position
66                 of individual bits.
67                 Bits are defined in kernel/include/sensors.h.
68
69 beep      2     Beep/interrupt enable and bitmask.
70                 The first value is 0 or 1 to globally disable
71                 or enable the beeps.
72                 The second value is a bitmask, with the
73                 same format as 'alarms' with same bit locations.
74                
75 curr[1-n]  3    Current max, min or hysteresis, and input value.
76                 Floating point values XX.X or XX.XX in Amps.
77                 The second value is preferably a hysteresis value,
78                 reported as a absolute current, NOT a delta from
79                 the max value.
80                 First two values are read/write and third is read only.
81
82 fan[1-3]  2     Fan minimum and input value.
83                 Two integers indicating RPM.
84                 First value is read/write and second is read only.
85
86 fan_div   3     Fan divisor.
87                 Integers in powers of two (1,2,4,8,16,32,64,128).
88                 Some chips only support values 1,2,4,8.
89                 Entries correspond to the fans[1-3].
90                 See doc/fan-divisors for details.
91
92 in[0-8]   3     Voltage min, max, and input value.
93                 Floating point values X.XX in volts from 0 to 4.01 volts.
94                 Actual voltage depends on the scaling resistors on the
95                 motherboard, as recommended in the chip datasheet.
96                 This varies by chip and by motherboard.
97                 Because of this variation, values are generally NOT scaled
98                 by the chip driver, and must be done by the application.
99                 However, some drivers (notably lm87 and via686a)
100                 do scale, with various degrees of success.
101                 These drivers will output the actual voltage.
102                 First two values are read/write and third is read only.
103                 Typical usage:
104                         in0     CPU #1 voltage (not scaled)
105                         in1     CPU #1 voltage (not scaled)
106                         in2     3.3V nominal (not scaled)
107                         in3     5.0V nominal (scaled)
108                         in4     12.0V nominal (scaled)
109                         in5     -12.0V nominal (scaled)
110                         in6     -5.0V nominal (scaled)
111                         in7     varies
112                         in8     varies
113
114 pwm[1-3]  1-2   Pulse width modulation fan control.
115                 Integer 0 - 255, read/write.
116                 255 is max or 100%.
117                 Corresponds to the fans 1-3.
118                 Second value, if present, is an enable (0 or 1)
119
120 sensor[1-3]  1  Sensor type selection.
121                 Integers 1,2,3, or thermistor Beta value (3435); read/write.
122
123 temp,
124 temp[1-4]  3    Temperature max, min or hysteresis, and input value.
125                 Floating point values XXX.X or XXX.XX in degrees Celsius.
126                 'temp' is used if there is only one temperature sensor on the
127                 chip; for multiple temps. start with 'temp1'.
128                 Temp1 is generally the sensor inside the chip itself,
129                 generally reported as "motherboard temperature".
130                 Temp2 to temp4 are generally sensors external to the chip
131                 itself, for example the thermal diode inside the CPU or a
132                 termistor nearby. The second value is preferably a hysteresis
133                 value, reported as a absolute temperature, NOT a delta from
134                 the max value.
135                 First two values are read/write and third is read only.
136
137 vid        1    CPU core voltage.
138                 Read only.
139                 Floating point X.XX or X.XXX corresponding to CPU core voltage
140                 as told to the sensor chip. Not always correct.
141
142 vrm        1    Voltage Regulator Module version number.
143                 "Floating point" X.X. Default 8.2.
144                 Affects the way the driver calculates the core voltage from
145                 the vid pins. See doc/vid for details.
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