On 10/16/2025 12:26 PM, Warner Losh wrote:


On Thu, Oct 16, 2025 at 8:12 AM Alan Somers <[email protected]> wrote:

    The "boot" command will give you a vague description like
    "shutdown" or "crash".


boot command? I don't have this on my system. How do yo uget that?

    If a crash was the cause then maybe your system isn't configured
    to make core dumps.  I suggest forcing a crash with
    "sysctl debug.kdb.panic=1" while you watch the screen to see what
    happens.


Yea. If it is a reboot, and crash dumps are enabled, and there's nothing is in /var/log/messages, you have limited options.

If there's a BMC, and it speaks IPMI, there might be something in the IPMI log if it was hardware triggered (ipmitool sel list):    1 |  Pre-Init  |0000001024| Processor #0xe4 | Presence detected | Asserted

Not sure if it helps in this case or not, but If you capture smartctl info regularly, you can some times infer from the disk power cycle count and power on hours if the box rebooted due to a power issue or not.

    ---Mike


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