Re: [PATCH 0/4] hw: make TCO watchdog actually work by default for Q35

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Oct 31, 2022 at 01:19:30PM +0000, Daniel P. Berrangé wrote:
> The TCO watchdog is unconditionally integrated into the Q35 machine
> type by default, but at the same time is unconditionally disabled
> from firing by a host config option that overrides guest OS attempts
> to enable it. People have to know to set a magic -global to make
> it non-broken

Incidentally I found that originally the TCO watchdog was not
unconditionally enabled. Its exposure to the guest could be
turned on/off using

  -global ICH9-LPC.enable_tco=bool

This was implemented for machine type compat, but it also gave
apps a way to disable the watchdog functionality. Unfortunately
that ability was discarded in this series:

  https://lore.kernel.org/all/1453564933-29638-1-git-send-email-ehabkost@redhat.com/

but the 'enable_tco' property still exists in QOM, but silently
ignored.

Seems we should either fix the impl of 'enable_tco', or remove the
QOM property entirely, so we don't pretend it can be toggled anymore.

With regards,
Daniel
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