linux-kernel - Re: 500 ms delay in time saved into RTC

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Message-ID: <0ce68f3f-fec7-1f1c-e70b-331c0752f6d6@gmail.com>
Date:   Mon, 19 Feb 2018 14:31:23 +0300
From:   Igor Plyatov <plyatov@...il.com>
To:     Karel Zak <kzak@...hat.com>,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>
Cc:     linux-kernel@...r.kernel.org,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        rtc-linux@...glegroups.com, util-linux@...r.kernel.org,
        J William Piggott <elseifthen@....com>
Subject: Re: 500 ms delay in time saved into RTC

Dear Karel,

> Would be possible to somehow detect what is the right default setting for
> --delay? I mean for example detect architecture / clock HW, etc.
>
> I have no problem with --delay, but it's tuning for advanced users and
> HW specific stuff. It would be nice to have something more portable.
>
>      Karel
>

As I understood, issue exists only at x86 platform, where 
MC146818-compatible RTC used.

But even if you will correctly detect platform, there is no guaranty to 
get exactly MC146818 RTC. RTC can be other type. It even can be not 
single in the system.

What is more or less usable is "/sys/class/rtc/rtcX/name" file, which 
contains driver name.
For x86 and MC146818-compatible RTC its name is "rtc_cmos". And it can 
be used to distinguish RTC type by hwclock utility.

Best wishes.
--
Igor Plyatov