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

[Andrew Jones <drjones@redhat.com>]

On Tue, Sep 16, 2014 at 10:38:11AM -0400, Andrew Jones wrote:
> 
> 
> ----- Original Message -----
> > 
> > 
> > ----- Original Message -----
> > > Il 16/09/2014 14:43, Andrew Jones ha scritto:
> > > > 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
> > > 
> > > Ok, I'll test and apply your patch then.
> > 
> > Actually, yeah, please apply now in order to get A7 boards working.
> > I'll do a follow-on patch to fix the case above (which will require
> > deciding how to hand per cpu data).
> 
> Post coffee, I don't see why I shouldn't just use SCTLR.C as my
> boolean, which is of course per cpu, and means the same thing,
> i.e. caches enabled or not. I'll send a v2 that drops
> mem_caches_enabled, and modifies the logic of the spin_lock asm.

Scratch this idea. It breaks the use of spin_lock from usr mode.
I think plan B is the best, which is; apply this patch, and then I'll
make mem_caches_enabled per cpu later, once we support per cpu data.

> > 
> > > 
> > > Once you change the code to enable caches, please consider hanging on
> > > spin_lock with caches disabled.
> > > 
> > > Paolo
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