• Tejun Heo's avatar
    sound: make OSS device number claiming optional and schedule its removal · 93fe4483
    Tejun Heo authored
    If any OSS support is enabled, regardless of built-in or module,
    sound_core claims full OSS major number (that is, the old 0-255
    region) to trap open attempts and request sound modules using custom
    module aliases.  This feature is redundant as chrdev already has such
    mechanism.  This preemptive claiming prevents alternative OSS
    implementation.
    
    The custom module aliases are scheduled to be removed and the previous
    patch made soundcore emit the standard chrdev aliases too to help
    transition.
    
    This patch schedule the feature for removal in a year and makes it
    optional so that developers and distros can try new things in the
    meantime without rebuilding the kernel.  The pre-claiming can be
    turned off by using SOUND_OSS_CORE_PRECLAIM and/or kernel parameter
    soundcore.preclaim_oss.
    
    As this allows sound minors to be individually grabbed by other users,
    this patch updates sound_insert_unit() such that if registering
    individual device region fails, it tries the next available slot.
    
    For details on removal plan, please read the entry added by this patch
    in feature-removal-schedule.txt .
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    93fe4483
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