.\" $NetBSD: amdzentemp.4,v 1.6.8.1 2020/04/24 17:46:44 martin Exp $
.\"-
.\" Copyright (c) 2008 Christoph Egger
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.\" $FreeBSD: src/share/man/man4/coretemp.4,v 1.4 2007/10/15 20:00:19 netchild Exp $
.\"
.Dd April 20, 2020
.Dt AMDZENTEMP 4 x86
.Os
.Sh NAME
.Nm amdzentemp
.Nd AMD Zen CPU family on-die digital thermal sensor
.Sh SYNOPSIS
.Cd "amdzentemp* at amdsmnbus?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the on-die digital thermal sensor present
on AMD Ryzen CPUs and some later AMD Opteron CPUs.
.Pp
These sensors provide 0.125\(deC accuracy.
There is one sensor for each CPU socket.
.Pp
The
.Nm
driver reports temperatures through the
.Xr envsys 4
API.
.Bl -column "CPUN sensor0" "Units" "Typical Use" -offset indent
.It Sy "Sensor" Ta Sy "Units" Ta Sy "Typical Use"
.It CPU Ns Em N No sensor0 Ta \(*mK Ta cpu Ns Em N No temperature
.El
.Sh SEE ALSO
.Xr amdtemp 4 ,
.Xr envsys 4 ,
.Xr envstat 8 ,
.Xr powerd 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 4.4
named
.Dq kate .
It was then ported to
.Nx 5.0
under the name
.Xr amdtemp 4 .
The
.Fx
version of the driver was updated with support for newer AMD CPUs.
For
.Nx ,
the support for the newer CPUs was separated into its own
.Nm
driver.
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Constantine A. Murenin Aq Mt cnst@openbsd.org
whilst at the University of Waterloo.
Porting of support for the newer AMD CPUs from
.Fx
was provided by
.An Ian Clark .
.Sh BUGS
The temperature reading provided to
.Xr envsys 4
needs to have a CPU-dependent offset applied.
For Ryzen X processors, the offset is 20\(deC, while for Threadripper
processors an offset of 27\(deC is needed.
.Pp
The sensor has a thermal-trip value which should be retrieved and
provided to
.Xr envsys 4
as the sensors critical-maximum value.