From 5ac6da669e2476dbdac89b357b05b5a79bc5b657 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sat, 10 Feb 2007 01:43:14 -0800 Subject: [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/mips/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/mips/Kconfig') diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 9d839a9c4b1a..1bc6d249be44 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -8,6 +8,10 @@ mainmenu "Linux/MIPS Kernel Configuration" menu "Machine selection" +config ZONE_DMA + bool + default y + choice prompt "System type" default SGI_IP22 -- cgit v1.2.3