Re: [Xen-devel] [PATCH v5 2/4] shutdown: Prepare for use of an enum in reset/shutdown_request

["Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>]

* Eric Blake (eblake@xxxxxxxxxx) wrote:
> On 04/28/2017 10:27 AM, Dr. David Alan Gilbert wrote:
> 
> >>>> +# Enumeration of various causes for shutdown.
> >>>> +#
> >>>> +# @host-qmp: Reaction to a QMP command, such as 'quit'
> >>>> +# @host-signal: Reaction to a signal, such as SIGINT
> >>>> +# @host-ui: Reaction to a UI event, such as closing the window
> >>>> +# @host-replay: The host is replaying an earlier shutdown event
> >>>> +# @host-error: Qemu encountered an error that prevents further use of 
> >>>> the guest
> >>>> +# @guest-shutdown: The guest requested a shutdown, such as via ACPI or
> >>>> +#                  other hardware-specific action
> >>>> +# @guest-reset: The guest requested a reset, and the command line
> >>>> +#               response to a reset is to instead trigger a shutdown
> >>>> +# @guest-panic: The guest panicked, and the command line response to
> >>>> +#               a panic is to trigger a shutdown
> >>>
> 
> > At a higher level, using your tags, I'm not sure where a reset triggered
> > by a fault detected by the hypervisor lives - e.g. an x86 triple fault
> > where the guest screws up so badly that it just gets reset.  Is
> > that a guest-reset or a guest-panic or what - neither case
> > was actually asked for by the guest itself.
> 
> Wouldn't that be host-error (qemu detected an error that prevents
> further execution of the guest without a reset - and a triple fault
> seems to fall into the category of the guest getting itself wedged
> rather than actually trying to reset)?  Except patch 3 only used
> SHUTDOWN_TYPE_HOST_ERROR in the xen portion of the patch.
> 
> So if any x86 expert has an opinion on where triple-fault handling is
> emulated, and what category should be used there, I'm welcome to
> tweaking this series.

It's pretty much on the border anyway, I don't think it matters too
much; it sounds perfectly reasonable.

Dave

> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
> 



--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK

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