From f0d6d1f6ff6f8525cfa396ec1969b8f402391445 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Thu, 9 Oct 2014 15:29:41 -0700 Subject: [PATCH] CMA: document cma=0 It isn't obvious that CMA can be disabled on the kernel's command line, so document it. Signed-off-by: Jean Delvare Cc: Joonsoo Kim Cc: Greg Kroah-Hartman Cc: Akinobu Mita Cc: Chuck Ebbert Cc: Marek Szyprowski Cc: Konrad Rzeszutek Wilk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 3 ++- drivers/base/Kconfig | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index a126a31dde02..809e880bc787 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -656,7 +656,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Sets the size of kernel global memory area for contiguous memory allocations and optionally the placement constraint by the physical address range of - memory allocations. For more information, see + memory allocations. A value of 0 disables CMA + altogether. For more information, see include/linux/dma-contiguous.h cmo_free_hint= [PPC] Format: { yes | no } diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 134f763d90fd..61a33f4ba608 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -252,6 +252,9 @@ config DMA_CMA to allocate big physically-contiguous blocks of memory for use with hardware components that do not support I/O map nor scatter-gather. + You can disable CMA by specifying "cma=0" on the kernel's command + line. + For more information see . If unsure, say "n".