amdzentemp(4) - NetBSD Manual Pages

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AMDZENTEMP(4)         NetBSD/x86 Kernel Interfaces Manual        AMDZENTEMP(4)


NAME

     amdzentemp -- AMD Zen CPU family on-die digital thermal sensor


SYNOPSIS

     amdzentemp* at amdsmnbus?


DESCRIPTION

     The amdzentemp driver provides support for the on-die digital thermal
     sensor present on AMD Ryzen CPUs and some later AMD Opteron CPUs.

     These sensors provide 0.125°C accuracy.  There is one sensor for each CPU
     socket.

     The amdzentemp driver reports temperatures through the envsys(4) API.

           Sensor          Units    Typical Use
           CPUN sensor0    µK       cpuN temperature


SEE ALSO

     amdtemp(4), envsys(4), envstat(8), powerd(8)


HISTORY

     The amdzentemp driver first appeared in OpenBSD 4.4 named ``kate''.  It
     was then ported to NetBSD 5.0 under the name amdtemp(4).  The FreeBSD
     version of the driver was updated with support for newer AMD CPUs.  For
     NetBSD, the support for the newer CPUs was separated into its own
     amdzentemp driver.


AUTHORS

     The amdzentemp driver was written by Constantine A. Murenin
     <cnst@openbsd.org> whilst at the University of Waterloo.  Porting of sup-
     port for the newer AMD CPUs from FreeBSD was provided by Ian Clark.


BUGS

     The temperature reading provided to envsys(4) needs to have a CPU-depen-
     dent offset applied.  For Ryzen X processors, the offset is 20°C, while
     for Threadripper processors an offset of 27°C is needed.

     The sensor has a thermal-trip value which should be retrieved and pro-
     vided to envsys(4) as the sensors critical-maximum value.

NetBSD 10.1                     April 20, 2020                     NetBSD 10.1