linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Prarit Bhargava <prarit@redhat.com>
To: John Stultz <john.stultz@linaro.org>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] time, Fix setting of hardware clock in NTP code
Date: Fri, 08 Feb 2013 18:44:50 -0500	[thread overview]
Message-ID: <51158DF2.3090702@redhat.com> (raw)
In-Reply-To: <51158643.1020204@linaro.org>



On 02/08/2013 06:12 PM, John Stultz wrote:
> On 02/08/2013 02:59 PM, Prarit Bhargava wrote:

> 
> Ok, I've got this queued in my tree. What sort of testing did you do with it?
> 
> I want to make sure we don't run into any bad interactions with the existing
> 15min cap on x86.

John,

I did the following:

I used powerpc pseries systems and tested this using both positive and negative
values of sys_tz.minuteswest, with both UTC and LOCAL in /etc/adjtime.  I dumped
values of 'hwclock -D' and date and confirmed that I no longer see time
increasing by sys_tz.minuteswest each reboot.

I also tested x86 32-bit and 64-bit as a sanity check and verified that the
current behaviour on those arches is the same; ie) I don't see *any* impact to
the x86 rtc.  I dumped values of 'hwclock -D' and date, and again confirmed that
I see no differences in values.  I did that with both UTC and LOCAL.

I also tested a powerpc box and set the hwclock (via BIOS) back to Dec 6 2012 to
see what would happen when I enabled ntp.  The system booted, set the system
time to Dec 6 2012, and then properly ended up with both system time AND hwclock
as Feb 8 2013 after systemd init .... (The *exact* time-of-day was correct as
well.  I just can't remember the time I did it ;) )

And I did the same thing (adjusting the BIOS date back) on x86. I only see the
hours and minutes change, as we expect.  The year, month, day are unaffected
with both UTC and LOCAL.

tl;dr  Yup.  Tested as much as I could think of doing before submitting.  Tested
on a both x86, powerpc.  Fixed the bug on powerpc.  No change in behavior seen
with x86.

If you want me to do some other test I certainly can give it a shot.

P.

  reply	other threads:[~2013-02-08 23:44 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-08 12:55 [PATCH] time, Fix setting of hardware clock in NTP code Prarit Bhargava
2013-02-08 21:46 ` John Stultz
2013-02-08 22:59   ` Prarit Bhargava
2013-02-08 23:12     ` John Stultz
2013-02-08 23:44       ` Prarit Bhargava [this message]
2013-02-08 23:50         ` John Stultz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=51158DF2.3090702@redhat.com \
    --to=prarit@redhat.com \
    --cc=john.stultz@linaro.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).