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libc/common: Allocate default malloc arena for non-minimal-libc uses

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When using the common malloc implementation on systems not using the
minimal C library, allocate a reasonable default malloc heap according to
the following rules (adopted from the Picolibc heap size defaults):

* When an MMU is available, allocate 16kB.
* When USERSPACE is enabled for a device with an MPU require PoT alignment,
  allocate 1024 bytes
* Otherwise, use all available memory.

Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Keith Packard 2023-03-29 10:21:34 -07:00 committed by Stephanos Ioannidis
parent 420bf1e444
commit 0a44b419ab
1 changed files with 19 additions and 1 deletions
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20
lib/libc/common/Kconfig
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@ -20,11 +20,29 @@ config COMMON_LIBC_MALLOC
config COMMON_LIBC_MALLOC_ARENA_SIZE
int "Size of the common C library malloc arena"
depends on COMMON_LIBC_MALLOC
default 0
default 0 if MINIMAL_LIBC
default 16384 if MMU
default 1024 if USERSPACE && MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT
default -1
help
Indicate the size in bytes of the memory arena used for
common C library malloc() implementation.
If set to zero, then no malloc() heap will be available.
If set to -1, then all remaining system RAM will be used for this
area.
If user mode is enabled, and MPU hardware has requirements that
regions be sized to a power of two and aligned to their size,
then this must be defined as a power of two or a compile error
will result.
When using the minimal C library, the default is to have no
malloc heap. Otherwise, on systems with an MMU the default is
16kB and all other systems will default to using all remaining
ram for the malloc heap.
config COMMON_LIBC_CALLOC
bool "Common C library calloc"
depends on COMMON_LIBC_MALLOC