Re: [Qemu-devel] [Qemu devel v9 PATCH 2/5] msf2: Microsemi Smartfusion2 System Register block

[Philippe Mathieu-Daudé]

Hi Peter,

On 09/18/2017 10:36 AM, Peter Maydell wrote:
> On 18 September 2017 at 14:27, sundeep subbaraya <address@hidden> wrote:
> > > > Hi Sundeep, Peter,
> > > >
> > > >
> > > > On 09/15/2017 01:59 PM, Subbaraya Sundeep wrote:
> > > > > +static void msf2_sysreg_write(void *opaque, hwaddr offset,
> > > > > +                          uint64_t val, unsigned size)
> > > > > +{
> > > > > +    MSF2SysregState *s = opaque;
> > > > > +    uint32_t newval = val;
> > > > > +
> > > > > +    offset >>= 2;
> > > > > +
> > > > > +    switch (offset) {
> > > > > +    case MSSDDR_PLL_STATUS:
> > > > > +        trace_msf2_sysreg_write_pll_status();
> > > > > +        break;
> > > > > +
> > > > > +    case ESRAM_CR:
> > > > > +    case DDR_CR:
> > > > > +    case ENVM_REMAP_BASE_CR:
> > > > > +        if (newval != s->regs[offset]) {
> > > > > +            qemu_log_mask(LOG_UNIMP,
> > > > > +                       TYPE_MSF2_SYSREG": remapping not supported\n");
> > > >
> > > >
> > > > I'd rather exit here than continue with inconsistent cpu, Peter what do
> > > > you recommend?
> >
> >
> > Could you please suggest.
>
> We shouldn't exit QEMU for something the guest can provoke. If
> the functionality isn't implemented then just LOG_UNIMP it.

This was commented here:
http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg02971.html

Guest remapping code is like non-return function. Hardware error here 
can not happen, so there is no more guest code after a remap request.
Continuing running QEMU will lead to chaos, that's why I recommend 
aborting instead of just LOG_UNIMP it.

Regards,

Phil.