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

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Oct 31, 2022 at 01:50:24PM +0000, Daniel P. Berrangé wrote:
> 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

i am inclined to say you are right and the fix is to fix the impl.

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