Thank you for your advice. I didn't notice it.
I'm adding followings according to your advice:
- range restrict for CMA_SIZE_MBYTES and *CMA_SIZE_PERCENTAGE*
I think this can prevent the wrong kernel option.
- change size_cmdline into default value SZ_16M
I am not sure this can prevent if cma=0 cmdline option is also with base and limit options.
I don't know how to send the second patch.
Please pardon me that I just copy the patch here.
--------------------------------- 8< -------------------------------------
From c283eaac41b044a2abb11cfd32a60fff034633c3 Mon Sep 17 00:00:00 2001
From: Gioh Kim <gioh.kim@xxxxxxx>
Date: Fri, 16 May 2014 16:15:43 +0900
Subject: [PATCH] drivers/base/Kconfig: restrict CMA size to non-zero value
The size of CMA area must be larger than zero.
If the size is zero, all physically-contiguous allocation
can be failed.
Signed-off-by: Gioh Kim <gioh.kim@xxxxxxxxx>
---
drivers/base/Kconfig | 14 ++++++++++++--
drivers/base/dma-contiguous.c | 3 ++-
2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 4b7b452..a7292ac 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -222,17 +222,27 @@ config DMA_CMA
if DMA_CMA
comment "Default contiguous memory area size:"
+config CMA_SIZE_MBYTES_DEFAULT
+ int
+ default 16
+
+config CMA_SIZE_MBYTES_MAX
+ int
+ default 1024
+
config CMA_SIZE_MBYTES
int "Size in Mega Bytes"
depends on !CMA_SIZE_SEL_PERCENTAGE
- default 16
+ range 1 CMA_SIZE_MBYTES_MAX
+ default CMA_SIZE_MBYTES_DEFAULT
help
Defines the size (in MiB) of the default memory area for Contiguous
- Memory Allocator.
+ Memory Allocator. This value must be larger than zero.
config CMA_SIZE_PERCENTAGE
int "Percentage of total memory"
depends on !CMA_SIZE_SEL_MBYTES
+ range 1 100
default 10
help
Defines the size of the default memory area for Contiguous Memory
diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c
index b056661..5b70442 100644
--- a/drivers/base/dma-contiguous.c
+++ b/drivers/base/dma-contiguous.c
@@ -125,7 +125,8 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
if (size_cmdline != -1) {
- selected_size = size_cmdline;
+ selected_size = ((size_cmdline == 0) ?
+ CONFIG_CMA_SIZE_MBYTES_DEFAULT : size_cmdline);
selected_base = base_cmdline;
selected_limit = min_not_zero(limit_cmdline, limit);
if (base_cmdline + size_cmdline == limit_cmdline)
--
1.7.9.5
2014-05-17 오전 2:45, Michal Nazarewicz 쓴 글:
On Fri, May 16 2014, Gioh Kim wrote:
If CMA_SIZE_MBYTES is allowed to be zero, there should be defense code
to check CMA is initlaized correctly. And atomic_pool initialization
should be done by __alloc_remap_buffer instead of
__alloc_from_contiguous if __alloc_from_contiguous is failed.
Agreed, and this is the correct fix.
IMPO, it is more simple and powerful to restrict CMA_SIZE_MBYTES_MAX
configuration to be larger than zero.
No, because it makes it impossible to have CMA disabled by default and
only enabled if command line argument is given.
Furthermore, your patch does *not* guarantee CMA region to always be
allocated. If CMA_SIZE_SEL_PERCENTAGE is selected for instance. Or if
user explicitly passes 0 on command line.
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