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cma: add placement specifier for "cma=" kernel parameter

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Currently, "cma=" kernel parameter is used to specify the size of CMA,
but we can't specify where it is located.  We want to locate CMA below
4GB for devices only supporting 32-bit addressing on 64-bit systems
without iommu.

This enables to specify the placement of CMA by extending "cma=" kernel
parameter.

Examples:
 1. locate 64MB CMA below 4GB by "cma=64M@0-4G"
 2. locate 64MB CMA exact at 512MB by "cma=64M@512M"

Note that the DMA contiguous memory allocator on x86 assumes that
page_address() works for the pages to allocate.  So this change requires
to limit end address of contiguous memory area upto max_pfn_mapped to
prevent from locating it on highmem area by the argument of
dma_contiguous_reserve().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Akinobu Mita 2014-06-04 16:06:54 -07:00 • committed by Linus Torvalds
parent 2bfc2862c4
commit 5ea3b1b2f8
4 changed files with 44 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

9
include/linux/dma-contiguous.h
View file

@ -88,7 +88,8 @@ static inline void dma_contiguous_set_default(struct cma *cma)
void dma_contiguous_reserve(phys_addr_t addr_limit);
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma);
phys_addr_t limit, struct cma **res_cma,
bool fixed);
/**
* dma_declare_contiguous() - reserve area for contiguous memory handling
@ -108,7 +109,7 @@ static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
{
struct cma *cma;
int ret;
ret = dma_contiguous_reserve_area(size, base, limit, &cma);
ret = dma_contiguous_reserve_area(size, base, limit, &cma, true);
if (ret == 0)
dev_set_cma_area(dev, cma);
@ -136,7 +137,9 @@ static inline void dma_contiguous_set_default(struct cma *cma) { }
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma) {
phys_addr_t limit, struct cma **res_cma,
bool fixed)
{
return -ENOSYS;
}