• Thierry Reding's avatar
    printk: only unregister boot consoles when necessary · 81cc26f2
    Thierry Reding authored
    Boot consoles are typically replaced by proper consoles during the boot
    process.  This can be problematic if the boot console data is part of
    the init section that is reclaimed late during boot.  If the proper
    console does not register before this point in time, the boot console
    will need to be removed (so that the freed memory is not accessed),
    leaving the system without output for some time.
    
    There are various reasons why the proper console may not register early
    enough, such as deferred probe or the driver being a loadable module.
    If that happens, there is some amount of time where no console messages
    are visible to the user, which in turn can mean that they won't see
    crashes or other potentially useful information.
    
    To avoid this situation, only remove the boot console when it resides in
    the init section.  Code exists to replace the boot console by the proper
    console when it is registered, keeping a seamless transition between the
    boot and proper consoles.
    Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Joe Perches <joe@perches.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    81cc26f2
printk.c 80.1 KB