Re: [PATCH kvm-unit-tests] arm: fix crash when caches are off

[Andrew Jones <drjones@redhat.com>]

----- Original Message -----
> Il 16/09/2014 14:12, Andrew Jones ha scritto:
> >> > Should it at least write 1 to the spinlock?
> > I thought about that. So on one hand we might get a somewhat functional
> > synchronization mechanism, which may be enough for some unit test that
> > doesn't enable caches, but still needs it. On the other hand, we know
> > its broken, so we don't really want any unit tests that need
> > synchronization
> > and don't enable caches. I chose to not write a 1 in the hope that if
> > a unit test introduces a race, that that race will be easier to expose
> > and fix. That said, I'm not strongly biased, as we'd still have a race,
> > which may or may not be easy to expose, either way. So if the majority
> > prefers a best effort approach, then I'll spin a v2.
> 
> The case I was thinking about was something like
> 
>     spin_lock()
>     enable caches
>     start other processors
>     spin_unlock()
> 
> I'm not sure if it makes sense though. :)

I don't think we need to worry about this case. AFAIU, enabling the
caches for a particular cpu shouldn't require any synchronization.
So we should be able to do

    enable caches
    spin_lock
    start other processors
    spin_unlock

drew

> 
> Paolo
>