Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo <otubo@redhat.com>]

On Fri, Sep 15, 2017 at 12:18:11PM +0200, Paolo Bonzini wrote:
> On 15/09/2017 11:06, Eduardo Otubo wrote:
> > QEMU fails when used with the following command line:
> > 
> >   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
> >   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
> >   Aborted (core dumped)
> > 
> > The 40p machine type already creates the device i82374. If specified in the
> > command line, it will try to create it again, hence generating the error. The
> > function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> > way to avoid this problem is to set user_creatable=false.
> > 
> > A possible fix in a near future would be making
> > isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
> > as well.
> > 
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> >  hw/dma/i82374.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > index 6c0f975df0..e76dea8dc7 100644
> > --- a/hw/dma/i82374.c
> > +++ b/hw/dma/i82374.c
> > @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
> >      dc->realize = i82374_realize;
> >      dc->vmsd = &vmstate_i82374;
> >      dc->props = i82374_properties;
> > +    dc->user_creatable = false;
> > +    /*
> > +     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> > +     *         if the device is instantiated twice.
> > +     */
> >  }
> >  
> >  static const TypeInfo i82374_info = {
> > 
> 
> This breaks "make check", doesn't it?
> 
> v2 should be the one that returns an error instead of asserting.

I guess I have misunderstood, then. I'll work on a patch to propagate
the error then.

Thanks,

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat