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What is /dev/rtc ? - Linux Setup, Configuration & Administration

Mplayer says it can't access /dev/rtc. It still works. Googling suggests that /dev/rtc is something to do with synchronizing. What exactly does it do (in simple terms?) Doug. -- Here lies one who meant well, tried a little, failed much:- surely that may be his epitaph, of which he need not be ashamed. -R.L. Stevenson (Christmas sermon)...

  1. #1

    Default What is /dev/rtc ?

    Mplayer says it can't access /dev/rtc. It still works.

    Googling suggests that /dev/rtc is something to do with synchronizing. What
    exactly does it do (in simple terms?)

    Doug.
    --
    Here lies one who meant well, tried a little, failed much:-
    surely that may be his epitaph, of which he need not be ashamed.
    -R.L. Stevenson (Christmas sermon)

    Doug Guest

  2. #2

    Default Re: What is /dev/rtc ?

    Doug Laidlaw <com.au> wrote: 
     

    rtc == Real Time Clock

    Try (needs kernel sources installed):
    /usr/src/linux*/Doentation/rtc.txt

    Check the permissions on /dev/rtc and correct them, if this is
    the problem.

    --
    Michael Heiming

    Remove +SIGNS and www. if you expect an answer, sorry for
    inconvenience, but I get tons of SPAM
    Michael Guest

  3. #3

    Default Re: What is /dev/rtc ?

    Doug writes: 

    It's used to read the hardware clock.
    --
    John Hasler
    gt.org
    Dancing Horse Hill
    Elmwood, Wisconsin
    John Guest

  4. #4

    Default Re: What is /dev/rtc ?

    Michael Heiming wrote:
     

    >
    > rtc == Real Time Clock
    >
    > Try (needs kernel sources installed):
    > /usr/src/linux*/Doentation/rtc.txt
    >
    > Check the permissions on /dev/rtc and correct them, if this is
    > the problem.
    >[/ref]
    /dev/rtc is O.K. but it is a symlink to /dev/misc/rtc, which is 640. I will
    make it 644.

    Doug.
    --
    A crank is a little thing that makes revolutions.
    -- Henry George, economist - attrib.

    Doug Guest

  5. #5

    Default Re: What is /dev/rtc ?

    Michael Heiming wrote:
     

    >
    > rtc == Real Time Clock
    >
    > Try (needs kernel sources installed):
    > /usr/src/linux*/Doentation/rtc.txt
    >
    > Check the permissions on /dev/rtc and correct them, if this is
    > the problem.
    >[/ref]
    Thanks Michael. I changed the permissions, but now it says:

    Linux RTC init error in ioctl (rtc_irqp_set 1024): Permission denied
    Try adding "echo 1024 > /proc/sys/dev/rtc/max-user-freq" to your startup
    scripts.

    I am running a 1.2 GHz Athlon and tried running that command from the
    command line, which made MPlayer happy. Should I make it permanent, and if
    so, where?

    Doug.
    --
    Silently one by one, in the infinite meadows of heaven
    Blossomed the lovely stars, the forget-me-nots of the angels.
    -- Longfellow.

    Doug Guest

  6. #6

    Default Re: What is /dev/rtc ?

    Doug Laidlaw <com.au> wrote:

    [..]
     
     

    Many distro use /etc/sysctl

    dev.rtc.max-user-freq = 1024

    Should do it, check 'man sysctl' for more info.

    If your system doesn't have this, you can put "echo ..." in
    rc.local/boot.local or whatever your distro uses on startup.

    --
    Michael Heiming

    Remove +SIGNS and www. if you expect an answer, sorry for
    inconvenience, but I get tons of SPAM
    Michael Guest

  7. #7

    Default Re: What is /dev/rtc ?

    Michael Heiming <michael+heiming.de> wrote: 
     
     [/ref]
     [/ref]
     

    Err, it's /etc/sysctl.conf of course.
     
     
     

    --
    Michael Heiming

    Remove +SIGNS and www. if you expect an answer, sorry for
    inconvenience, but I get tons of SPAM
    Michael Guest

  8. #8

    Default Re: What is /dev/rtc ?

    Doug Laidlaw <com.au> wrote: 
     

    real-time clock. It counts to infinity fast and steadily.

    Peter
    P.T. Guest

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