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authorMarek Szyprowski <m.szyprowski@samsung.com>2011-12-29 13:09:51 +0100
committerMarek Szyprowski <m.szyprowski@samsung.com>2012-05-21 15:09:38 +0200
commitc79095092834a18ae74cfc08def1a5a101dc106c (patch)
treec6cd81c38b92dcdb269288ab9a125bc13f4bb339 /Documentation/kernel-parameters.txt
parent0a2b9a6ea93650b8a00f9fd5ee8fdd25671e2df6 (diff)
downloadlinux-c79095092834a18ae74cfc08def1a5a101dc106c.tar.bz2
ARM: integrate CMA with DMA-mapping subsystem
This patch adds support for CMA to dma-mapping subsystem for ARM architecture. By default a global CMA area is used, but specific devices are allowed to have their private memory areas if required (they can be created with dma_declare_contiguous() function during board initialisation). Contiguous memory areas reserved for DMA are remapped with 2-level page tables on boot. Once a buffer is requested, a low memory kernel mapping is updated to to match requested memory access type. GFP_ATOMIC allocations are performed from special pool which is created early during boot. This way remapping page attributes is not needed on allocation time. CMA has been enabled unconditionally for ARMv6+ systems. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Michal Nazarewicz <mina86@mina86.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Tested-by: Rob Clark <rob.clark@linaro.org> Tested-by: Ohad Ben-Cohen <ohad@wizery.com> Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> Tested-by: Robert Nelson <robertcnelson@gmail.com> Tested-by: Barry Song <Baohua.Song@csr.com>
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diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 669e8bb52b94..41996c68a5cd 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -520,6 +520,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
a hypervisor.
Default: yes
+ coherent_pool=nn[KMG] [ARM,KNL]
+ Sets the size of memory pool for coherent, atomic dma
+ allocations if Contiguous Memory Allocator (CMA) is used.
+
code_bytes [X86] How many bytes of object code to print
in an oops report.
Range: 0 - 8192