Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: [PATCH[ RTC: Add rtc_year_days() to calculate tm_yday | Date | Wed, 7 Jun 2006 15:48:31 -0700 (PDT) |
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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.
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