From: Pavel Machek <pavel@suse.cz>
To: Riley Williams <rhw@MemAlpha.cx>
Cc: kernel list <linux-kernel@vger.kernel.org>
Subject: Re: PROBLEM: Linux updates RTC secretly when clock synchronizes
Date: Sat, 10 Nov 2001 21:04:41 +0100 [thread overview]
Message-ID: <20011110210441.B19664@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <20011109223053.A964@atrey.karlin.mff.cuni.cz> <Pine.LNX.4.21.0111092247070.14996-100000@Consulate.UFP.CX>
In-Reply-To: <Pine.LNX.4.21.0111092247070.14996-100000@Consulate.UFP.CX>
Hi!
> >> ...it gets "Port busy" when it tries to access the RTC ports that the
> >> RTC driver built into the kernel already has opened exclusively. At
> >> least, that's my understanding of the situation at present.
>
> > It does not work that way. Userland does iopl(0), and then it just
~~~~~~~
sorry, this was meant
to be iopl(3).
> > bangs any port it wants to.
>
> If any user can do that, then Linux is borken solid.
Only root can do that.
> 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.
> >>> We are talking root only here.
>
> >> Are we?
> >>
> >> Unless I've misunderstood the arguments so far, the aim is to take
> >> the RTC driver out of the kernel altogether and replace it with a
> >> usermode driver to do the same thing. As I see it, that opens up far
> >> too many
>
> > 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.
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 20:05 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 [this message]
2001-11-10 20:35 ` Riley Williams
2001-11-10 20:43 ` Pavel Machek
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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