Re: [PATCH for-8.2 1/4] hw/rtc/m48t59: Use 64-bit arithmetic in set_alarm()

[Peter Maydell <peter.maydell@linaro.org>]

On Fri, 21 Jul 2023 at 10:09, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> On 20/7/23 17:58, Peter Maydell wrote:
> > In the m48t59 device we almost always use 64-bit arithmetic when
> > dealing with time_t deltas.  The one exception is in set_alarm(),
> > which currently uses a plain 'int' to hold the difference between two
> > time_t values.  Switch to int64_t instead to avoid any possible
> > overflow issues.
> >
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> >   hw/rtc/m48t59.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
>
> Similarly:
>
> -- >8 --
> --- a/hw/rtc/m48t59.c
> +++ b/hw/rtc/m48t59.c
> @@ -88,7 +88,7 @@ static M48txxInfo m48txx_sysbus_info[] = {
>   static void alarm_cb (void *opaque)
>   {
>       struct tm tm;
> -    uint64_t next_time;
> +    int64_t next_time;
>       M48t59State *NVRAM = opaque;

Why? next_time should always be positive here, I think.

-- PMM