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Peter and Charlie thanks again!! Peter: "Do you know the RTC's battery is good? (Does the board say the battery is OK on the console when it boots?)" - YES "rtc-m48t86 rtc-m48t86: battery ok" Charlie: "Do you get a message during boot like "cannot access hardware clock by any known method"? -NO but the link technique you described is key: I spent hours on the clock yesterday, solution identified. This is what I found: Even with ep93xx-rtc marked 'not set' in .config: CONFIG_RTC_LIB=y CONFIG_RTC_CLASS=y CONFIG_RTC_HCTOSYS=y CONFIG_RTC_HCTOSYS_DEVICE="rtc1" # CONFIG_RTC_DEBUG is not set # RTC interfaces CONFIG_RTC_INTF_SYSFS=y CONFIG_RTC_INTF_PROC=y CONFIG_RTC_INTF_DEV=y ... CONFIG_RTC_DRV_M48T86=y ... # on-CPU RTC drivers # CONFIG_RTC_DRV_EP93XX is not set ... The ep93xx-rtc is still initialized during boot: >ep93xx-rtc ep93xx-rtc: rtc core: registered ep93xx-rtc as rtc0 >rtc-m48t86 rtc-m48t86: rtc core: registered m48t86 as rtc1 I can set it with: date 090218272101 > Thu Sep 2 18:27:00 UTC 2101 'hwclock -w' 'hwclock' shows the right time after. But 'hwclock --debug' reveals as you said that I am in fact setting /dev/rtc0 which has no battery backup So: 'ln -s /dev/rtc1 /dev/rtc' Allowed me to set the m48t86 with 'hwclock -w'. After doing it, the bootup changes from: >rtc-m48t86 rtc-m48t86: setting system clock to 2070-01-03 01:20:43 UTC (3155937643) [I didn't know time_t went that high, I thought it was signed 32bit int!] to the much more reasonable: >rtc-m48t86 rtc-m48t86: setting system clock to 2010-09-02 18:43:07 UTC (1283452987) But after boot 'hwclock' still reveals that the time kept by /dev/rtc0 is wrong (Jan1, 1970) and that the system time emitted by date is the same. So again: 'ln -s /dev/rtc1 /dev/rtc' followed by: 'hwclock' reveals that we have switched to the real clock: >Thu Sep 2 18:44:50 2010 -0.443011 seconds and then: 'hwclock -s' sets the Unix time. So it seems that my solution is to add: ln -s /dev/rtc1 /dev/rtc hwclock -s to my /etc/rc.local I also add a note here that our application software, once running on ARM, will execute this to high accuracy using a GPS receiver, so that will be another interesting activity in the next several weeks. __._,_.___
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