From: Jamie Lokier <jamie@shareable.org>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, Dor Laor <dlaor@redhat.com>,
Anthony Liguori <aliguori@us.ibm.com>,
Glauber Costa <glommer@redhat.com>,
qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [PATCH v3 0/5] Improve PC RTC emulation
Date: Tue, 15 Sep 2009 18:50:41 +0100 [thread overview]
Message-ID: <20090915175041.GA2786@shareable.org> (raw)
In-Reply-To: <20090915113603.8313.49563.stgit@mchn012c.ww002.siemens.net>
Jan Kiszka wrote:
> The aim of this series is to allow using the emulated PC RTC (MC146818)
> as a reliable time source for guests. This is particularly useful if the
> host runs NTP or has otherwise access to an accurate clock while the
> guest has not (no network, impossible to add an NTP implementation
> etc.).
I approve of these patches.
But still, how exactly is it useful, without NTP? Afaik, Linux does
not read the RTC except once at boot time, so it probably still needs
NTP or something like it to have reliable time. However, it does
_write_ the RTC every 11 minutes if running NTP - does that affect the
emulated behaviour? Or does the emulated RTC ignore writes?
Do any other OSes read the RTC more than once after boot?
-- Jamie
next prev parent reply other threads:[~2009-09-15 17:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-15 11:36 [Qemu-devel] [PATCH v3 0/5] Improve PC RTC emulation Jan Kiszka
2009-09-15 11:36 ` [Qemu-devel] [PATCH v3 2/5] win32: Drop dead dyntick timer code Jan Kiszka
2009-09-15 11:36 ` [Qemu-devel] [PATCH v3 3/5] Introduce QEMU_CLOCK_HOST Jan Kiszka
2009-09-15 11:36 ` [Qemu-devel] [PATCH v3 4/5] Refactor RTC command line switches Jan Kiszka
2009-10-06 10:32 ` Mark McLoughlin
2009-10-06 10:59 ` [PATCH] Register rtc options for -set (was: [Qemu-devel] [PATCH v3 4/5] Refactor RTC command line switches) Jan Kiszka
2009-09-15 11:36 ` [Qemu-devel] [PATCH v3 1/5] Rename QEMU_TIMER_* to QEMU_CLOCK_* Jan Kiszka
2009-09-15 11:36 ` [Qemu-devel] [PATCH v3 5/5] Enable host-clock-based RTC Jan Kiszka
2009-09-15 17:50 ` Jamie Lokier [this message]
2009-09-15 18:51 ` [Qemu-devel] Re: [PATCH v3 0/5] Improve PC RTC emulation Jan Kiszka
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=20090915175041.GA2786@shareable.org \
--to=jamie@shareable.org \
--cc=aliguori@us.ibm.com \
--cc=blauwirbel@gmail.com \
--cc=dlaor@redhat.com \
--cc=glommer@redhat.com \
--cc=jan.kiszka@siemens.com \
--cc=qemu-devel@nongnu.org \
/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).