2.6.19.2: bad reads/writes from/to CMOS clock

2.6.19.2: bad reads/writes from/to CMOS clock

[yavuz]

Hi everyone,

I am running 2.6.19.2 kernel from kernel.org.

This is my first SMP kernel. 

The problem I describe below has not happend with non-SMP kernels ever...

I have installed my new AMD64 x2 4800 CPU just a few days ago. My mobo is Asus A8N SLI
(Nvidia chipset).

My problem with this new setup is that my CMOS clock is thrown off by varying 
amounts of time. I have seen system times as long as ten months into future, and as
long as 25 days in the past. At the moment my system clock has correct 
hh:mm:ss, but it shows the date Jan 1st, instead of correct 25th.

In last few days have systematically checked CMOS clock after shutdown and before
boot-up.

I have observed CMOS clock set to a wrong value, immediately after shutdown. 
I also ended up with a wrong system time following a boot after verifying 
correctness of the CMOS clock.

Problem does not happen 100% of the time. But 6-7 times in a week is bad 
enough. 

I searched mailing list archives, and found some NMI-RTC race condition discussion, 
and some other discussions about timers not running, clock ticks being missed
etc. But they were all at least one year old. The fixes to those should have found
their way into 2.6.19 kernels.

I would appreciate any ideas on how to follow-up on this problem. 

I am eager to try things, collect data as needed. Just tell me what to do.

Thanks in advance.




Yavuz Onder

[x86-64, CMOS/RTC] Re: 2.6.19.2: bad reads/writes from/to CMOS clock

[Oleg Verych]

26-01-2007:
> I am running 2.6.19.2 kernel from kernel.org.

2.6.18 debian, didn't see before, but maybe it was just big uptime ;)

> This is my first SMP kernel. 
>
> The problem I describe below has not happend with non-SMP kernels ever...
>
> I have installed my new AMD64 x2 4800 CPU just a few days ago. My mobo is Asus A8N SLI
> (Nvidia chipset).

UP ASUS A4K x86-64 CPU Mobile Athlon 64 3200+

> My problem with this new setup is that my CMOS clock is thrown off by varying 
> amounts of time. I have seen system times as long as ten months into future, and as
> long as 25 days in the past. At the moment my system clock has correct 
> hh:mm:ss, but it shows the date Jan 1st, instead of correct 25th.

I saw bad CMOS read, but CMOS itself was OK, after checking it with
hwclock or reboot by magic IRQ.

[]
> I would appreciate any ideas on how to follow-up on this problem. 
>
> I am eager to try things, collect data as needed. Just tell me what to do.
>
> Thanks in advance.

> Yavuz Onder

I don't know, because it was month or so ago. And i'm usual for bugs
(or curved hands ;).
____

Re: 2.6.19.2: bad reads/writes from/to CMOS clock

[Yavuz Onder]

I have since found out that SMP kernels should(must?) have Enhanced RTC 
support built-in.

It is stated in kernel config help for Enhanced RTC support, and I found 
a number of references on the net as well.

Now I wonder why selecting SMP does not set Enhanced RTC support to "Y" 
automatically?

I am building a kernel right now, and will monitor for a week or so, 
then come back and report if it removes the problem.

Yavuz

yavuz@teksavvy.com wrote:
> Hi everyone,
>
> I am running 2.6.19.2 kernel from kernel.org.
>
> This is my first SMP kernel. 
>
> The problem I describe below has not happend with non-SMP kernels ever...
>
> I have installed my new AMD64 x2 4800 CPU just a few days ago. My mobo is Asus A8N SLI
> (Nvidia chipset).
>
> My problem with this new setup is that my CMOS clock is thrown off by varying 
> amounts of time. I have seen system times as long as ten months into future, and as
> long as 25 days in the past. At the moment my system clock has correct 
> hh:mm:ss, but it shows the date Jan 1st, instead of correct 25th.
>
> In last few days have systematically checked CMOS clock after shutdown and before
> boot-up.
>
> I have observed CMOS clock set to a wrong value, immediately after shutdown. 
> I also ended up with a wrong system time following a boot after verifying 
> correctness of the CMOS clock.
>
> Problem does not happen 100% of the time. But 6-7 times in a week is bad 
> enough. 
>
> I searched mailing list archives, and found some NMI-RTC race condition discussion, 
> and some other discussions about timers not running, clock ticks being missed
> etc. But they were all at least one year old. The fixes to those should have found
> their way into 2.6.19 kernels.
>
> I would appreciate any ideas on how to follow-up on this problem. 
>
> I am eager to try things, collect data as needed. Just tell me what to do.
>
> Thanks in advance.
>
>
>
>
> Yavuz Onder
>
>