diff options
| author | David Rientjes <rientjes@google.com> | 2011-05-16 13:54:10 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2011-05-16 14:03:28 -0700 |
| commit | dc382fd5bcca7098a984705ed6ac880f539d068e (patch) | |
| tree | c1e3cba89fcb91092061fecd5a2d688335e30216 /arch/x86/Kconfig | |
| parent | e5a10c1bd12a5d71bbb6406c1b0dbbc9d8958397 (diff) | |
x86, mm: Allow ZONE_DMA to be configurable
ZONE_DMA is unnecessary for a large number of machines that do not
require less than 32-bit DMA addressing, e.g. ISA legacy DMA or PCI
cards with a restricted DMA address mask.
This patch allows users to disable ZONE_DMA for x86 if they know they
will not be using such devices with their kernel.
This prevents the VM from unnecessarily reserving a ratio of memory
(defaulting to 1/256th of system capacity) with lowmem_reserve_ratio
for such allocations when it will never be used.
Signed-off-by: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.00.1105161353560.4353@chino.kir.corp.google.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 648fca42ae6..0eb801a75de 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -112,7 +112,14 @@ config MMU def_bool y config ZONE_DMA - def_bool y + bool "DMA memory allocation support" if EXPERT + default y + help + DMA memory allocation support allows devices with less than 32-bit + addressing to allocate within the first 16MB of address space. + Disable if no such devices will be used. + + If unsure, say Y. config SBUS bool |