Re: [Xen-devel] [PATCH 13/17] x86: don't create Dom0 if neither PV nor HVM is available

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Oct 12, 2018 at 04:28:21PM +0100, Andrew Cooper wrote:
> On 12/10/18 16:12, Jan Beulich wrote:
> >>>> On 04.10.18 at 17:43, <wei.liu2@xxxxxxxxxx> wrote:
> >> This will give us a Xen setting in idle loop. This doesn't have
> >> practical use except for debugging purpose.
> > Hmm, that's an acceptable alternative to the panic() variant, but
> > I'd still prefer that one. Again - let's see if Andrew has an opinion
> > either way.
> 
> I think that, for the purpose of keeping our interfaces clean, being
> able to compile without PV and without HVM is a useful property
> (especially as randconfig should hit it one in every 4 cases).
> 
> I've specifically needed to have no dom0 for certain debugging in the
> past.  (The HPET series to fix the broken MSI handler, which I realise
> still hasn't made its way upstream yet.)
> 
> I'm less certain however if implementing it like this is wise.  I
> implemented it with a "nodom0" command line parameter, and left the rest
> of the functionality intact.
> 
> In particular, one fuzzing idea I have is to have a tiny AFL stub on the
> end of the serial port, at which point, having no dom0 but PV and HVM
> fully compiled in would be the ideal position.
> 
> I'm sorry if this isn't necessarily a very helpful answer.  I'd be
> tempted to drop this patch for now, and let the first person with a
> concrete usecase to decide exactly how a no-dom0 system would look.

Sure. I don't mind dropping this patch.

Wei.

> 
> ~Andrew

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