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Date:      Tue, 26 Jun 2018 07:05:22 -0700
From:      Eitan Adler <lists@eitanadler.com>
To:        Gary Jennejohn <gljennjohn@gmail.com>
Cc:        Konstantin Belousov <kostikbel@gmail.com>, amd64@freebsd.org,  "current@freebsd.org" <current@freebsd.org>
Subject:   Re: Ryzen public erratas
Message-ID:  <CAF6rxgmym9kzvTba9bakH72prfOEDDfmCmzZ01yGTtjibHdT0w@mail.gmail.com>
In-Reply-To: <20180619115030.5491af33@ernst.home>
References:  <20180613103535.GP2493@kib.kiev.ua> <CAF6rxg=ua-WneapcVF3UWaRT79P=fO9fVGwYsntVmJrx3rTJKA@mail.gmail.com> <CAF6rxgksYSS1g_jRoGiENBXY9pNW3NUmkJ9qKJ1k%2BYw08iaVMw@mail.gmail.com> <20180619115030.5491af33@ernst.home>

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On 19 June 2018 at 02:50, Gary Jennejohn <gljennjohn@gmail.com> wrote:
> On Mon, 18 Jun 2018 22:44:13 -0700
> Eitan Adler <lists@eitanadler.com> wrote:
>
>> On 13 June 2018 at 04:16, Eitan Adler <lists@eitanadler.com> wrote:
>> > On 13 June 2018 at 03:35, Konstantin Belousov <kostikbel@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?
>>
>
> I had sysctl machdep.idle_mwait=1 and machdep.idle=acpi before
> applying the shell script.  I had multiple lockups every week,
> sometimes multiple lockups per day.

This makes me curious about why I didn't experience lockups.  Perhaps my
BIOS defaulted to something else?

With these settings:

machdep.idle: acpi
machdep.idle_mwait: 1

-- 
Eitan Adler



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