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Bug#660039: marked as done (rtc no longer available under linux 3.2.4-1)

Your message dated Wed, 15 Feb 2012 21:46:16 -0500
with message-id <[🔎] 4F3C6DF8.4030102@fifthhorseman.net>
and subject line Re: rtc no longer available under linux 3.2.4-1
has caused the Debian Bug report #660039,
regarding rtc no longer available under linux 3.2.4-1
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
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-- 
660039: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=660039
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
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 <ben@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

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--- End Message ---
--- Begin Message --- 
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

--- End Message ---
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