Ryzen public erratas

Eitan Adler lists at eitanadler.com
Tue Jun 19 05:44:46 UTC 2018

On 13 June 2018 at 04:16, Eitan Adler <lists at eitanadler.com> wrote:
> On 13 June 2018 at 03:35, Konstantin Belousov <kostikbel at gmail.com> wrote:
>> Today I noted that AMD published the public errata document for Ryzens,
>> https://developer.amd.com/wp-content/resources/55449_1.12.pdf
>> Some of the issues listed there looks quite relevant to the potential
>> hangs that some people still experience with the machines.  I wrote
>> a script which should apply the recommended workarounds to the erratas
>> that I find interesting.
>> To run it, kldload cpuctl, then apply the latest firmware update to your
>> CPU, then run the following shell script.  Comments indicate the errata
>> number for the workarounds.
>> Please report the results.  If the script helps, I will code the kernel
>> change to apply the workarounds.
>> #!/bin/sh
>> # Enable workarounds for erratas listed in
>> # https://developer.amd.com/wp-content/resources/55449_1.12.pdf
>> # 1057, 1109
>> sysctl machdep.idle_mwait=0
>> sysctl machdep.idle=hlt
> Is this needed if it was previously machdep.idle: acpi ?

This might explain why I've never seen the lockup issues mentioned by
other people. What would cause my machine to differ from others?

Eitan Adler

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