Messages in this thread | | | Date | Sat, 10 Nov 2001 21:43:21 +0100 | From | Pavel Machek <> | Subject | Re: PROBLEM: Linux updates RTC secretly when clock synchronizes |
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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. - 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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