lkml.org 
[lkml]   [2001]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: PROBLEM: Linux updates RTC secretly when clock synchronizes
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.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:13    [W:0.061 / U:1.660 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site