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Date:      Thu, 3 May 2018 11:40:24 +0300
From:      Andriy Gapon <avg@FreeBSD.org>
To:        "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
Subject:   hpet vs suspend to ram
Message-ID:  <8d3f5a6f-f2be-f2e1-18d5-f774f4909694@icyb.net.ua>

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Just want to share a strange problem that I see on one system.

If I use HPET as an eventtimer, then after a seemingly successful resume
the system starts to act weird.  It becomes unresponsive for periods of
time, then it gets more normal, then it's sluggish, then unresponsive
again.  After some time struggling the system finally locks up entirely.

I see this problem both with FreeBSD and Linux (tested with Ubuntu 16
and 17).

If I use any other timer hardware, then everything is okay.
Also, if I switch to HPET after a resume, then it's okay too.
I tried uncommenting the code in acpi_hpet.c that disables the HPET
before suspend, but it didn't change anything.

I suspect that the problem is with SMM code, but don't know how to check
it or whether it would make any difference.
I also tried disabling various devices (e.g. USB) through BIOS config, but that
also didn't help.

The system uses Asus M4A89GTD PRO motherboard.

-- 
Andriy Gapon



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