[gentoo-user] System date/time goes to GMT when PC wakes from hibernate

[gentoo-user] System date/time goes to GMT when PC wakes from hibernate

[Walter Dnes]

  I have a bunch of spreadsheets, browser tabs, etc, open all the time,
scattered over various work areas.  Rather than re-open them every day,
I simply hibernate, using suspend-to-disk.  This way, things are where I
left them.

  The past couple of months, when the machine comes up from hibernation,
the clock is a few hours ahead.  Now it's 4 hours ahead.  It was 5 hours
ahead before the switch to daylight savings time.  This looks
suspiciously like GMT.  GMT is 5 hours ahead of EST, and 4 hours ahead
of EDT.

  I dug deeper.  Apparently, it's just the "kernel system time" that
gets bumped forward when it wakes up from hibernation.  The BIOS clock
is OK.  As a heavy-handed hack, I've inserted the line...

OnResume 01 hwclock --hctosys

...into my /etc/hibernate/hibernate.conf.  This copies over the BIOS
time to the kernel system date.  It works, but I'd really like to know
why it's necessary in the first place.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: [gentoo-user] System date/time goes to GMT when PC wakes from hibernate

[Fernando Rodriguez]

On Monday, April 06, 2015 5:03:11 PM Walter Dnes wrote:
>   I have a bunch of spreadsheets, browser tabs, etc, open all the time,
> scattered over various work areas.  Rather than re-open them every day,
> I simply hibernate, using suspend-to-disk.  This way, things are where I
> left them.
> 
>   The past couple of months, when the machine comes up from hibernation,
> the clock is a few hours ahead.  Now it's 4 hours ahead.  It was 5 hours
> ahead before the switch to daylight savings time.  This looks
> suspiciously like GMT.  GMT is 5 hours ahead of EST, and 4 hours ahead
> of EDT.
> 
>   I dug deeper.  Apparently, it's just the "kernel system time" that
> gets bumped forward when it wakes up from hibernation.  The BIOS clock
> is OK.  As a heavy-handed hack, I've inserted the line...
> 
> OnResume 01 hwclock --hctosys
> 
> ...into my /etc/hibernate/hibernate.conf.  This copies over the BIOS
> time to the kernel system date.  It works, but I'd really like to know
> why it's necessary in the first place.
> 

There's an option CONFIG_RTC_HCTOSYS on the kernel to do it automatically. I 
think it uses utc so if you use localtime it may mess it up. This also came up 
recently on this list but I can't remember what the problem was so you may 
want to look there.

-- 
Fernando Rodriguez

Re: [gentoo-user] System date/time goes to GMT when PC wakes from hibernate

[Matti Nykyri]

On Mon, Apr 06, 2015 at 06:13:41PM -0400, Fernando Rodriguez wrote:
> > 
> > ...into my /etc/hibernate/hibernate.conf.  This copies over the BIOS
> > time to the kernel system date.  It works, but I'd really like to know
> > why it's necessary in the first place.
> > 
> 
> There's an option CONFIG_RTC_HCTOSYS on the kernel to do it automatically. I 
> think it uses utc so if you use localtime it may mess it up. This also came up 
> recently on this list but I can't remember what the problem was so you may 
> want to look there.

Don't store hwclock in localtime. It is a hack and you are asking for trouble.
Just store it in UTC. That way the worst mishap is that it gets 1 second to
a wrong direction if you happen to hit a leap second. With localtime you will
always have a change for worse 2 times a year when summer time kicks in.

-- 
-Matti

[gentoo-user] [SOLVED] System date/time goes to GMT when PC wakes from hibernate

[Walter Dnes]

On Mon, Apr 06, 2015 at 06:13:41PM -0400, Fernando Rodriguez wrote

> There's an option CONFIG_RTC_HCTOSYS on the kernel to do it
> automatically. I think it uses utc so if you use localtime it may
> mess it up. This also came up recently on this list but I can't
> remember what the problem was so you may want to look there.

  Thanks, I think that's the problem.

# CONFIG_RTC_HCTOSYS is not set

...on both my desktop, and on the netbook.  The only difference is that
the netbook's Poulsbo chipset (bleagh) doesn't play nice with hibernate,
so I do a full shutdown, and the startup is from the text console login
prompt.  The problem didn't show up when I was re-installing (32 -> 64
bit upgrade) on my desktop, and doing full shutdowns and rebooting.  So
this seems

  I seem to remember this popping up as a new option recently during a
kernel upgrade...

Device Drivers > Real Time Clock
[ ]   Set system time from RTC on startup and resume

  This appears to do automatically what I do with the hwclock command in
the OnResume option.  Like 99% of all new stuff on "make oldconfig", I
said "No".  This time, it came back to bite me.  Next kernel upgrade,
I'll have to set that option on.

-- 
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications