> [Severity: High]
> This is a pre-existing issue, but does this time_after() comparison
> allow bypassing the 1-week hardware limit on 32-bit systems?

This is fixed later.

> [Severity: Medium]
> This is a pre-existing issue, but what happens if the RZN1_RTC_ALW register
> is uninitialized and wday is 0?
> 
> Calling fls(0) - 1 would evaluate to -1. If the current time is a Saturday
> (tm_now.tm_wday == 6), delta_days evaluates to 0, which bypasses
> the if (delta_days) block and leaves tm->tm_wday = -1.
> 
> Since the core function rtc_valid_tm() does not check tm_wday, would this
> propagate a bogus alarm date to the caller?

This looks worth investigating to me. On RZN1, ALW is default 0.