lkml.org 
[lkml]   [2012]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [uml-devel] /sys/class/tty/tty0/active?
    From
    Greg, Kay,

    >> Is that a problem for UML somehow?

    The login on ttyX takes 30+ seconds.
    This very ugly and mostly wrong hack makes the login fast again:
    mount -o bind /sys/class/tty/console/ /sys/class/tty/tty0/

    /sys/class/tty/console/active exists and contains "tty0"...

    > In general, the "crippled" environments might not really the right
    > thing too run full-blown user login managers like logind.
    >
    > The main systemd 'init' will not have any problems with that, but
    > running logind might not really work out under UML.
    >
    > Depending how far full-OS support in UML should go, logind should
    > either not run inside UML, or if, UML should provide the needed bits
    > for in virtual consoles.

    Any x86 distribution works fine in UML.
    If this will be no longer true due to systemd then better no systemd developer
    ever crosses my way. ;-)

    > If it is not to be solved otherwise, maybe logind needs more
    > VT-avoiding logic like this:
    >  http://cgit.freedesktop.org/systemd/systemd/commit/?id=addedec48ba0ffc4472ef6d3b5a45c9d4239f1cd

    Yeah, would make sense.
    Many systems don't have CONFIG_VT set.

    One good thing is that systemd seems to uncover a nasty bug in UML's
    console driver.
    A login on tty0 crashes UML.

    UML's console driver (arch/um/drivers/line.c) implements tty_operations.
    The crash happens because the tty subsystem calls the driver's close()
    function and later
    write_room() or chars_in_buffer().

    write_room() and chars_in_buffer() fail badly because close() already
    cleaned up the driver's private data...

    Greg, is UML's assumption wrong that after closing the tty no call to
    write_room() or chars_in_buffer() can happen?
    I have no idea why systemd is able to trigger this, UML's console
    driver is old and has always worked quite well.

    --
    Thanks,
    //richard
    --
    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: 2012-01-27 10:23    [W:0.023 / U:2.900 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site