Red Hat Bugzilla – Bug 56777
Power management turns off daytime clock!
Last modified: 2007-04-18 12:38:27 EDT
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.2.1) Gecko/20010901 Description of problem: Bad: power management support turns off the daytime clock. Did not happen with RH 7.1 (just upgraded). Machine is the Toshiba 8000M desktop, Intel Pentium III, 1GHz, 512MB RAM. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1.Install RH 7.2 2.Don't touch machine all night 3. Actual Results: In the morning (9AM) the machine shows 4AM (approx). When I run netdate to update the clock my screen blanks momentarily. BTW, I see the same kind of screen blanking twice during the boot sequence (during those messages [OK]...). NOTE: while the clock seems to be turned off, my modem is not, because my ISP connection is still active in the morning. Expected Results: Machine should keep the correct time. Additional info:
Correction to my submission: Looks like Red Hat 7.2 out of the box does not suffer from this problem because I just tested booting with the original kernel. This leads naturally to a question that I submitted to Red Hat (as a registered user) but never received a response to. Namely, where do I find the exact kernel configuration that was used to build the kernel that is shipped with Red Hat 7.2? I used the srpm that is on the CD but it does not seem to be ready to compile with the particular configuration used by Red Hat. If I can find this configuration then I can figure our what kernel config option is causing this clock problem.
The easiest way to get to the config file is to install the kernel-source rpm; if you have done that the config files (there's more than one, eg one for smp etc) in /usr/src/linux-2.4/configs ...........
I already installed the kernel source RPM yet I cannot find the source tree and configuration used by Red Hat to build Version 7.2. All I find are a bunch of empty directories with names like i386, i686, etc., and some patch files. I am looking under /usr/src/... I tried building a kernel using the latest 2.4.16 source, and there was a promising lead: the char device with major/minor 10/183 could not be found at boot time. Turns out this is the real-time clock, and when I enabled RTC in the configuration this boot error message went away. Unfortunately, this did not fix the clock problem. It is now 12AM, yet the clock on my PC shows 3PM after sitting idle all day. It would be helpful if I can find the source tree and configs used by Red Hat. Dominick
You are probably talking about the kernel-2.4.X-Y.src.rpm; there also is a kernel-source-2.4.X-Y.i386.rpm ! that one puts the full source in /usr/src/linux-2.4 and the configs in the configs subdirectory of that
I tried the original Red Hat 7.2 kernel again. I let it run all day today, and again my clock is behind (by 2 hours), so finding the kernel source is not going to help. My PC keeps the right time only when I run Windows! To reset the time I run netdate, and when I do this my screen blanks (seems to go into sleep mode). I have to hit a key to wake it up, and at that point the time has been correctly set by netdate. Another strange behavior when I run the original kernel is that my PPP dialup connection is always dropped after a while, yet it stays up when I run kernel 2.4.16! (It stays up because I use 'lcp-echo-interval 60' in my /etc/ppp/options file, but this does not seem to have any effect when I run the RH 7.2 kernel!) Any ideas?
I have the resolution, but I would not call this "NOTABUG". The man page for hwclock explains that there are two clocks, the CMOS (or hardware) clock and the software (interrupt driven) clock maintained by Linux (initialized from the hardware clock at boot time). The problems described above were caused by the fact that in my BIOS I had "SUSPEND AFTER 20 MINS" turned on. This does not cause any problems for Windows 2000, but it does for Linux. Looks like when the machine goes into SUSPEND mode the Linux clock runs slow (or stops?). Note that the hardware clock itself does not run slow, and the Linux software clock can be fixed with /sbin/hwclock --hctosys. Running this command when the clock is slow will put the monitor to sleep because it thinks it has been idle for a long time. The work-around is to turn off SUSPEND mode completely in the BIOS.