Bug#660039: rtc no longer available under linux 3.2.4-1
notfound 660039 3.2.4-1 quit Daniel Kahn Gillmor wrote: argh. It looks like this is not the fault of the kernel, so i'm closing this ticket. [... nice full explanation snipped ...] Thanks for explaining. Hopefully next time it happens we can learn more. -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20120216095524.GB31212@burratino
Bug#660039: rtc no longer available under linux 3.2.4-1
Package: linux-2.6 Version: 3.2.4-1 Subject: rtc no longer available under linux 3.2.4-1 I have an asus eeePC 900. lshw reports it as: description: Notebook product: 900 (90OAM09AB5312111U205Q) vendor: ASUSTeK Computer INC. version: 0704 When it wakes from sleep under 3.2.4-1, the system's clock is off by days, which caused me to look into the real-time clock. Apparently something changed between 3.2.1-1 and 3.2.4-1. When i booted it with 3.2.1-1, the kernel would record the following info about the rtc: [1.505626] rtc_cmos 00:03: RTC can wake from S4 [1.505886] rtc_cmos 00:03: rtc core: registered rtc_cmos as rtc0 [1.505999] rtc0: alarms up to one month, 114 bytes nvram, hpet irqs [1.517779] rtc_cmos 00:03: setting system clock to 2012-01-22 18:22:12 UTC (1327256532) Booting it with 3.2.4-1, i see this info instead: [1.503620] rtc_cmos 00:03: RTC can wake from S4 [1.503887] rtc_cmos 00:03: rtc core: registered rtc_cmos as rtc0 [1.503980] rtc_cmos 00:03: only 24-hr supported [1.515880] /build/buildd-linux-2.6_3.2.4-1-i386-61WrTr/linux-2.6-3.2.4/debian/build/source_i386_none/drivers/rtc/hctosys.c: unable to open rtc device (rtc0) Also, trying to talk to the hardware clock now gives me: 0 pip:~# hwclock --show --debug hwclock from util-linux 2.20.1 hwclock: Open of /dev/rtc failed: No such file or directory No usable clock interface found. hwclock: Cannot access the Hardware Clock via any known method. 70 pip:~# Whereas before it would report as expected. looking for the cause of the change, i see that: https://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.2.2 suggests there's been a change in the rtc code: - commit 36a8176166397d103352670327e1b20d334b5c7d Author: Ben Hutchings b...@decadent.org.uk Date: Tue Jan 10 15:11:02 2012 -0800 drivers/rtc/interface.c: fix alarm rollover when day or month is out-of-range commit e74a8f2edb92cb690b467cea0ab652c509e9f624 upstream. Commit f44f7f96a20a (RTC: Initialize kernel state from RTC) introduced a potential infinite loop. If an alarm time contains a wildcard month and an invalid day ( 31), or a wildcard year and an invalid month (= 12), the loop searching for the next matching date will never terminate. Treat the invalid values as wildcards. Fixes http://bugs.debian.org/646429, http://bugs.debian.org/653331 - however, /usr/share/doc/linux-image-3.2.0-1-686-pae/changelog.Debian.gz suggests that 3.1.8-1 had already introduced the same change by bwh: * rtc: Fix alarm rollover when day or month is out-of-range (Closes: #646429) So i'm not sure what to make of the situation, but i'm happy to provide any additional debugging info that would be useful. Regards, --dkg pgpeokelVBMJF.pgp Description: PGP signature
Bug#660039: rtc no longer available under linux 3.2.4-1
Hi Daniel,
Daniel Kahn Gillmor wrote:
Booting it with 3.2.4-1, i see this info instead:
[1.503620] rtc_cmos 00:03: RTC can wake from S4
[1.503887] rtc_cmos 00:03: rtc core: registered rtc_cmos as rtc0
[1.503980] rtc_cmos 00:03: only 24-hr supported
Weird. Reproducible? Does Linus's master behave the same way?
Can you bisect?
This is from
rtc_control = CMOS_READ(RTC_CONTROL);
[...]
if (is_valid_irq(rtc_irq) !(rtc_control RTC_24H)) {
dev_warn(dev, only 24-hr supported\n);
CMOS_READ() is declared in arch/x86/include/asm/mc146818rtc.h and
defined in arch/x86/kernel/rtc.c. None of this code has changed
recently.
Puzzled,
Jonathan
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Bug#660039: rtc no longer available under linux 3.2.4-1
On 02/15/2012 06:00 PM, Jonathan Nieder wrote: Weird. Reproducible? Does Linus's master behave the same way? Can you bisect? argh. It looks like this is not the fault of the kernel, so i'm closing this ticket. I tried rolling back to 3.2.1-1 from snapshot.debian.net: linux-image-3.2.0-1-686-pae_3.2.1-1_i386.deb SHA1: fb5ca95149378def1b12d4c314af928ab4f8d180 and it turned out that this machine was having the same rtc problems after reboot to this older kernel (and on 3.1.8-2, which i tried as well). So something must have happened to my hardware that randomly coincided with my switching kernels :( I tried removing power and batteries from the machine, and booting to different kernels, and the rtc still failed. On my sixth reboot, i went into the BIOS setup, manually changed the time of the clock by a little bit, and chose Exit and Save (or whatever its moral equivalent is). That must have reset something in the hardware, because now (rebooting into 3.2.4-1) the rtc is back to working as normal. Apologies for the false alarm over what appears to be some kind of flakey hardware hiccup. --dkg -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/4f3c6df8.4030...@fifthhorseman.net
