Bug#827323: linux: Regression v4.5 -> v4.6: system freeze after suspend/resume due to iAMT watchdog
Hi
Also there is a third bug in systemd - it does not check if watchdog is alarm only, like iAMT.
In theory to achieve system reboot on timeout systemd should iterate over all available watchdogs and select one that is not alarm only.
Thanks
--
Sasha
-----Original Message-----
From: Sebastian Reichel [mailto:sre@debian.org]
Sent: Wednesday, June 15, 2016 18:10
To: Usyskin, Alexander <alexander.usyskin@intel.com>
Cc: 827323@bugs.debian.org
Subject: Re: Bug#827323: linux: Regression v4.5 -> v4.6: system freeze after suspend/resume due to iAMT watchdog
Hi,
On Wed, Jun 15, 2016 at 01:25:53PM +0000, Usyskin, Alexander wrote:
> It may be that fdd9b8655933 uncovered the bug in iTCO_wdt because it
> actually removes iAMT watchdog and new implementation does not creates
> one for not provisioned ME.
>
> So before that patch there was two watchdog devices and systemd maybe
> worked with iAMT one. After that patch only one watchdog exists in the
> system - iTCO and system works with it.
Yes, looks like /dev/watchdog was iAMT watchdog on older kernels:
4.5:
Jun 15 01:26:36 earth systemd[1]: Hardware watchdog 'INTCAMT', version 0 Jun 15 01:26:36 earth systemd[1]: Failed to set timeout to 30s: Invalid argument
4.6:
Jun 15 01:24:49 earth systemd[1]: Hardware watchdog 'iTCO_wdt', version 0 Jun 15 01:24:49 earth systemd[1]: Set hardware watchdog to 30s.
Thanks for you help. So I guess there are two bugs, which are both unrelated to iAMT watchdog, but uncovered by this change:
1. systemd's watchdog logic seems to be broken after suspend/resume, so that the watchdog times out. It must be systemd's fault, since wd_keepalive does not trigger the bug. Previous kernels worked, since operations on INTCAMT were basically no-ops without provisioned ME.
2. iTCO_wdt hangs the system instead of restarting it.
-- Sebastian
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