Messages in this thread | | | Date | Sat, 10 Nov 2001 21:04:41 +0100 | From | Pavel Machek <> | Subject | Re: PROBLEM: Linux updates RTC secretly when clock synchronizes |
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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/
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