From: Pavel Machek <pavel@suse.cz>
To: Riley Williams <rhw@MemAlpha.cx>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: Linux updates RTC secretly when clock synchronizes
Date: Sat, 10 Nov 2001 21:43:21 +0100 [thread overview]
Message-ID: <20011110214321.G19664@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <20011110210441.B19664@atrey.karlin.mff.cuni.cz> <Pine.LNX.4.21.0111102030150.12260-100000@Consulate.UFP.CX>
In-Reply-To: <Pine.LNX.4.21.0111102030150.12260-100000@Consulate.UFP.CX>
Hi!
> >> Just out of curiosity, what is wrong with the idea of having the
> >> kernel at iopl(0), any kernel modules at either iopl(1) or iopl(2)
> >> and apps at iopl(3) ??? There is obviously something, but I've no
> >> idea what.
>
> > It ... just is not that way. Kernel + modules run at ring 0,
> > userland at ring 3.
>
> I know that much. I was just curious whether there was any particular
> reason why it was that way.
>
> Somebody suggested that it was because of "scheduling hooplas" causing a
> serious loss of performance if modules were moved to ring 1. I've no
> idea whether such is the case
Yep, it would be slower that way, and it would be nightmare to implement.
> >>> No. Aim is to leave /dev/rtc in kernel, but make kernel never write
> >>> to RTC at its own will.
>
> >> I've no problem with that at all, but the bulk of the comments I've
> >> seen in this thread have been very clear about taking /dev/rtc out
> >> of the kernel and into a userspace daemon, with the kernel just
> >> providing access to the relevant ports to the first app to claim
> >> them.
>
> > I do not think so.
> >
> > The person who tries to kill /dev/rtc from kernel is going to have
> > some problems with me.
>
> They've been getting problems from me - I just checked, and the main
> suggestion appears to be to replace /dev/rtc with a sysctl call. I can't
> see the point in that myself, and /dev/rtc makes far more sense to me.
>
> I will add that I personally see no problem with the kernel reading RTC
> on boot to set the syste clock, although some of the correspondents
> appear to have problems with that idea as well.
So we agree with each other. Good.
Pavel
--
Casualities in World Trade Center: 6453 dead inside the building,
cryptography in U.S.A. and free speech in Czech Republic.
next prev parent reply other threads:[~2001-11-10 20:43 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-31 0:33 PROBLEM: Linux updates RTC secretly when clock synchronizes Ian Maclaine-cross
2001-10-31 1:05 ` Kurt Roeckx
2001-10-31 2:55 ` Ian Maclaine-cross
2001-10-31 11:52 ` Kurt Roeckx
2001-11-01 0:52 ` Riley Williams
2001-11-01 1:26 ` Kurt Roeckx
2001-11-01 13:57 ` Alex Bligh - linux-kernel
2001-11-02 9:50 ` Riley Williams
2001-11-03 11:41 ` Alex Bligh - linux-kernel
2001-11-03 18:35 ` Riley Williams
2001-11-03 19:19 ` Alex Bligh - linux-kernel
2001-11-03 21:04 ` Kurt Roeckx
2001-11-06 10:01 ` Pavel Machek
2001-11-06 9:57 ` Pavel Machek
2001-11-02 12:16 ` Pavel Machek
2001-11-05 23:08 ` Riley Williams
2001-11-06 10:17 ` Pavel Machek
2001-11-07 0:00 ` Riley Williams
2001-11-07 0:44 ` Alex Bligh - linux-kernel
2001-11-07 1:01 ` Kurt Roeckx
2001-11-07 1:15 ` Alex Bligh - linux-kernel
2001-11-07 9:24 ` Russell King
2001-11-08 12:26 ` Pavel Machek
2001-11-08 23:00 ` Riley Williams
2001-11-09 9:32 ` Pavel Machek
2001-11-09 21:11 ` Riley Williams
2001-11-09 21:30 ` Pavel Machek
2001-11-09 22:54 ` Riley Williams
2001-11-09 23:10 ` Mark Zealey
2001-11-10 20:04 ` Pavel Machek
2001-11-10 20:35 ` Riley Williams
2001-11-10 20:43 ` Pavel Machek [this message]
2001-11-10 20:49 ` Doug McNaught
2001-11-06 0:20 ` Ian Maclaine-cross
2001-11-06 10:18 ` Pavel Machek
2001-11-08 5:09 ` Ian Maclaine-cross
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