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    [PATCH] optional ZONE_DMA: introduce CONFIG_ZONE_DMA · 66701b14
    Christoph Lameter authored
    
    
    This patch simply defines CONFIG_ZONE_DMA for all arches.  We later do special
    things with CONFIG_ZONE_DMA after the VM and an arch are prepared to work
    without ZONE_DMA.
    
    CONFIG_ZONE_DMA can be defined in two ways depending on how an architecture
    handles ISA DMA.
    
    First if CONFIG_GENERIC_ISA_DMA is set by the arch then we know that the arch
    needs ZONE_DMA because ISA DMA devices are supported.  We can catch this in
    mm/Kconfig and do not need to modify arch code.
    
    Second, arches may use ZONE_DMA in an unknown way.  We set CONFIG_ZONE_DMA for
    all arches that do not set CONFIG_GENERIC_ISA_DMA in order to insure backwards
    compatibility.  The arches may later undefine ZONE_DMA if their arch code has
    been verified to not depend on ZONE_DMA.
    
    Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
    Cc: Andi Kleen <ak@suse.de>
    Cc: "Luck, Tony" <tony.luck@intel.com>
    Cc: Kyle McMartin <kyle@mcmartin.ca>
    Cc: Matthew Wilcox <willy@debian.org>
    Cc: James Bottomley <James.Bottomley@steeleye.com>
    Cc: Paul Mundt <lethal@linux-sh.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    66701b14