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From: Frederick Gotham <cauldwell.thomas@gmail.com>
To: barebox@lists.infradead.org
Subject: Issue CPU instructions to start watchdog?
Date: Mon, 20 Jan 2020 11:33:13 +0000	[thread overview]
Message-ID: <CALtZhhMAHMh0HBatmQVL=uU6hYBuK3wvYPntqbQ-7rR5OzX_xA@mail.gmail.com> (raw)

I'm developing an embedded Linux device, and I'm using Barebox as a
part of Buildroot. The CPU is x64 with 4 cores, and it has an Intel
TCO watchdog timer.

The exact processor I'm using is the Intel Silver N5000, and the
datasheet for it says:
"TCO_TMR is the watchdog timer provided by the ACPI block. It is used
by an OS monitor for OS crashes."

When I boot up Barebox, it does not have the file "/dev/watchdog".
I've tried a few different things but I just simply can't get Barebox
to recognise the Intel watchdog timer.

Ideally I would like to have the watchdog timer start running at Power
On, however my current BIOS  hasn't got any watchdog settings, and so
until I get a new BIOS (which might never happen), I have to start the
watchdog timer from within Barebox in order to get the device to
reboot if the Linux kernel freezes while it's loading.

At this stage I think I might actually have to write assembler to
issue instructions to the CPU to start the Watchdog timer. I have
looked this up and it's definitely not straight-forward, e.g.
interfacing with the ACPI block and its registers... I would be pretty
much writing a device driver.

Anyone got any ideas?

I really need my device to reboot if the Linux kernel freezes while loading.

Frederick

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             reply	other threads:[~2020-01-20 11:33 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-20 11:33 Frederick Gotham [this message]
2020-01-20 15:05 ` Ahmad Fatoum

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