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dlmalloc: do memset in malloc init as new default config

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This commit introduces new config: CONFIG_SYS_MALLOC_CLEAR_ON_INIT.

This config is an expert option and is enabled by default.

The all amount of memory reserved for the malloc, is by default set
to zero in mem_malloc_init(). When the malloc reserved memory exceeds
few MiB, then the boot process can slow down.

So disabling this config, is an expert option to reduce the boot time,
and can be disabled by Kconfig.

Note:
After disable this option, only calloc() will return the pointer
to the zeroed memory area. Previously, without this option,
the memory pointed to untouched malloc memory region, was filled
with zeros. So it means, that code with malloc() calls should
be reexamined.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Przemyslaw Marczak
2015-03-04 14:01:24 +01:00
committed by Tom Rini
parent 41ac233c61
commit 0aa8a4ad99
2 changed files with 31 additions and 9 deletions
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30
Kconfig
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@@ -72,13 +72,31 @@ config SYS_MALLOC_F_LEN
initial serial device and any others that are needed.
menuconfig EXPERT
bool "Configure standard U-Boot features (expert users)"
help
This option allows certain base U-Boot options and settings
to be disabled or tweaked. This is for specialized
environments which can tolerate a "non-standard" U-Boot.
Only use this if you really know what you are doing.
bool "Configure standard U-Boot features (expert users)"
default y
help
This option allows certain base U-Boot options and settings
to be disabled or tweaked. This is for specialized
environments which can tolerate a "non-standard" U-Boot.
Only use this if you really know what you are doing.
if EXPERT
config SYS_MALLOC_CLEAR_ON_INIT
bool "Init with zeros the memory reserved for malloc (slow)"
default y
help
This setting is enabled by default. The reserved malloc
memory is initialized with zeros, so first malloc calls
will return the pointer to the zeroed memory. But this
slows the boot time.
It is recommended to disable it, when CONFIG_SYS_MALLOC_LEN
value, has more than few MiB, e.g. when uses bzip2 or bmp logo.
Then the boot time can be significantly reduced.
Warning:
When disabling this, please check if malloc calls, maybe
should be replaced by calloc - if expects zeroed memory.
endif
endmenu # General setup
menu "Boot images"