path: root/arch/arm26/ACKNOWLEDGEMENTS
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authorChristoph Lameter <clameter@sgi.com>2007-02-10 01:43:14 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-11 10:51:19 -0800
commit5ac6da669e2476dbdac89b357b05b5a79bc5b657 (patch)
tree45b16221dd4f246595638e5fb6f629ddda96ff33 /arch/arm26/ACKNOWLEDGEMENTS
parent339ba9b15df58199b9783a23af234e947ec9e6ba (diff)
As Andi pointed out: CONFIG_GENERIC_ISA_DMA only disables the ISA DMA channel management. Other functionality may still expect GFP_DMA to provide memory below 16M. So we need to make sure that CONFIG_ZONE_DMA is set independent of CONFIG_GENERIC_ISA_DMA. Undo the modifications to mm/Kconfig where we made ZONE_DMA dependent on GENERIC_ISA_DMA and set theses explicitly in each arches Kconfig. Reviews must occur for each arch in order to determine if ZONE_DMA can be switched off. It can only be switched off if we know that all devices supported by a platform are capable of performing DMA transfers to all of memory (Some arches already support this: uml, avr32, sh sh64, parisc and IA64/Altix). In order to switch ZONE_DMA off conditionally, one would have to establish a scheme by which one can assure that no drivers are enabled that are only capable of doing I/O to a part of memory, or one needs to provide an alternate means of performing an allocation from a specific range of memory (like provided by alloc_pages_range()) and insure that all drivers use that call. In that case the arches alloc_dma_coherent() may need to be modified to call alloc_pages_range() instead of relying on GFP_DMA. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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