diff options
| author | Christoph Lameter <clameter@sgi.com> | 2007-02-10 01:43:14 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-11 10:51:19 -0800 |
| commit | 5ac6da669e2476dbdac89b357b05b5a79bc5b657 (patch) | |
| tree | 45b16221dd4f246595638e5fb6f629ddda96ff33 /arch/powerpc | |
| parent | 339ba9b15df58199b9783a23af234e947ec9e6ba (diff) | |
[PATCH] Set CONFIG_ZONE_DMA for arches with GENERIC_ISA_DMA
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>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/Kconfig | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index f08e80a0bf0..0088c5ebca7 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -977,6 +977,10 @@ config ISA have an IBM RS/6000 or pSeries machine or a PReP machine, say Y. If you have an embedded board, consult your board documentation. +config ZONE_DMA + bool + default y + config GENERIC_ISA_DMA bool depends on PPC64 || POWER4 || 6xx && !CPM2 |