Re: [Qemu-devel] [PATCH 2/2] tpm_tis: Return 0 for every register in case of failure mode

[Stefan Berger]

On 12/13/2017 05:26 AM, Marc-André Lureau wrote:
> Hi Stefan
>
> On Sat, Nov 11, 2017 at 4:39 AM, Stefan Berger
> <address@hidden> wrote:
> > Rather than returning ~0, return 0 for every register in case of
> > failure mode. The '0' is better to indicate that there's no device
> > there.
> >
> > Signed-off-by: Stefan Berger <address@hidden>
> > ---
> >   hw/tpm/tpm_tis.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/tpm/tpm_tis.c b/hw/tpm/tpm_tis.c
> > index eca3374..d0bdd96 100644
> > --- a/hw/tpm/tpm_tis.c
> > +++ b/hw/tpm/tpm_tis.c
> > @@ -519,7 +519,7 @@ static uint64_t tpm_tis_mmio_read(void *opaque, hwaddr addr,
> >       uint8_t v;
> >
> >       if (tpm_backend_had_startup_error(s->be_driver)) {
> > -        return val;
> > +        return 0;
> >       }
> it's not obvious to me why it's better. Could you detail a bit more the reason?
>
> why not change the initialization of val instead?

http://patchwork.ozlabs.org/patch/838042/