Re: [PATCH[ RTC: Add rtc_year_days() to calculate tm_yday

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <20060607193311.GH13165@flint.arm.linux.org.uk>
By author:    Russell King <rmk+lkml@arm.linux.org.uk>
In newsgroup: linux.dev.kernel
>
> On Wed, Jun 07, 2006 at 08:26:09PM +0200, Andrew Victor wrote:
> > RTC: Add exported function rtc_year_days() to calculate the tm_yday
> > value.
> 
> Is there a good reason for this?  I ask the question because the x86
> /dev/rtc driver says:
> 
>          * Only the values that we read from the RTC are set. We leave
>          * tm_wday, tm_yday and tm_isdst untouched. Note that while the
>          * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
>          * only updated by the RTC when initially set to a non-zero value.
> 
> So it seems the established modus operandi for RTC interfaces is "don't
> trust wday, yday and isdst".
> 

"Be conservative in what you send, liberal in what you accept."

	- Mr. Protocol

In this case it seems a good idea to set these fields correctly, but
not rely upon them, unless there are known cases where that causes
trouble.

	-hpa