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Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration |
Date: |
Fri, 11 Sep 2009 10:54:49 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Jamie Lokier wrote:
> Anthony Liguori wrote:
>>> Besides the interface thing, I'm also interesting in comments on the
>>> other core idea, the selectable RTC base clock. Do we want this knob? Do
>>> we want host_clock unconditionally? Or should the other RTC that
>>> currently use the host time already also gain vm_clock support over the
>>> time?
>>>
>> Hard to say. Doesn't the rtc keep track of wallclock time even on power
>> off? I think using host_clock unconditionally does actually make sense.
>
> Sometimes it's useful to offset the emulated clock for one reason or
> another, hence the -startdate options. But having it run at the
> correct speed is usually useful :-)
Indeed.
>
> Also, sometimes (due to licenses with wallclock limits) it's useful
> for a guest to not see much time pass when the guest is powered off,
> although it still needs to be positive.
I'm not sure if this is a common use case. And it currently only seems
to be support by very few RTCs, the MC146818 being the most prominent one.
I'm now a fan of converting the latter to the common scheme of using the
host's system time (here via host_clock) and watch out for the need of
adding -rtc clock=vm.
>
> Will the -startdate functionality be maintained with the RTC changes?
Yes, just like -localtime, this will still be supported of course.
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
- [Qemu-devel] [PATCH 5/5] Enable host-clock-based RTC, (continued)
- [Qemu-devel] [PATCH 5/5] Enable host-clock-based RTC, Jan Kiszka, 2009/09/09
- [Qemu-devel] [PATCH 2/5] win32: Drop dead dyntick timer code, Jan Kiszka, 2009/09/09
- [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Anthony Liguori, 2009/09/09
- Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Jamie Lokier, 2009/09/09
- Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration,
Jan Kiszka <=
- Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Dor Laor, 2009/09/13
- [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Jan Kiszka, 2009/09/13
- [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Anthony Liguori, 2009/09/14
- [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Jan Kiszka, 2009/09/14
- Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Markus Armbruster, 2009/09/09
Re: [Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Gerd Hoffmann, 2009/09/10
[Qemu-devel] Re: [PATCH 0/5] Refactor and enhance RTC configuration, Blue Swirl, 2009/09/09