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Date:      Tue, 5 Nov 2019 12:44:06 -0500
From:      Brennan Vincent <brennan@umanwizard.com>
To:        freebsd-current@freebsd.org
Subject:   Kernel panics sometimes resulting in no core dump.
Message-ID:  <9C7D409D-7305-4E3A-9F66-F518A8D321B8@umanwizard.com>

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(Note: I have also posted this to the forums, but upon reading the forum =
guidelines more carefully I realized the mailing list is probably a =
better venue. So if you are also a forum reader, I apologize for the =
extra churn.)

Hello, I am running 13-CURRENT (compiled recently from source using =
default build settings) and recently I have been kernel panics every so =
often. They can happen at any time but seem to be more likely when the =
system is running a graphical environment and is at high load (e.g., =
during `make -j64 buildworld`).

I have configured my system to collect core dumps: my swap partition is =
50 GB (large enough to contain any conceivable minidump), `dumpon` =
reports that it is indeed configured as a dump partition, and I have =
`savecore_enable=3D"YES"` in /etc/rc.conf. I also have the sysctl =
`debug.debugger_on_panic` set to 0, which seems to be necessary for core =
dumps to happen (instead of breaking into the debugger on panic). =
Before, when that sysctl was set to 1, my graphical environment would =
hand; now it reboots. The changing behavior depending on the value of =
`debug.debugger_on_panic` is what makes me think this really is a kernel =
panic, as opposed to some other possible issue that could cause a crash.

The weird thing is that when I manually cause a panic via `sudo sysctl =
debug.kdb.panic=3D1` , my system reboots as expected, and a core dump =
**does** get generated and saved in /var/crash! So it's only the =
mysterious random crashes that aren't causing core dumps.

Can anyone help me figure out why core dumps are not getting generated, =
and how I can possibly debug what is going on?=




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