Re: [Qemu-devel] [Qemu-ppc] [QEMU-PPC] [PATCH V3 6/6] target/ppc/spapr: Add H-Call H_GET_CPU_CHARACTERISTICS

[David Gibson]

On Thu, Jan 18, 2018 at 02:30:27PM -0600, Eric Blake wrote:
> On 01/18/2018 02:11 AM, Alexey Kardashevskiy wrote:
> 
> >>>> I think you just assert() for this.  The only way these could get a
> >>>> different value is if there's a bug elsewhere.
> >>>
> >>>
> >>> Why not return H_HARDWARE or other error?
> >>
> >> Because what's the guest supposed to do with it. 
> > 
> > "oops"
> > 
> >> This is an internal
> >> qemu problem, so it should be dealt with via an internal qemu
> >> mechanism.
> > 
> > Do we have assert() enabled in production? If not, then assert == noop,
> > error_report is just a noise.
> 
> See commit 262a69f4.  Yes, assert() is enabled in production, for
> security reasons (aka it's easier to do that than to audit that
> migration is still safe even with no-op asserts).

TBH, assert()s usually aren't disabled in production.  That's the
theory behind them, but in practice AFAICT, the debugging utility
almost always outweighs the performance cost which is usually pretty
small.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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