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mm: Enable a dedicated kernel heap on BUILD_FLAT via MM_KERNEL_HEAP

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Signed-off-by: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>
This commit is contained in:
Gustavo Henrique Nihei
2023-01-11 15:32:05 -03:00
committed by Xiang Xiao
parent 047f7f8d3a
commit a3e253b4a3
5 changed files with 34 additions and 15 deletions
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mm/Kconfig
+17 -9
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@@ -26,16 +26,24 @@ config MM_CUSTOMIZE_MANAGER
endchoice
config MM_KERNEL_HEAP
bool "Support a protected, kernel heap"
default y
depends on !BUILD_FLAT
bool "Kernel dedicated heap"
default n if BUILD_FLAT
default y if BUILD_PROTECTED || BUILD_KERNEL
---help---
Partition heap memory into two parts: (1) a protected, kernel-mode
heap accessible only by the NuttX kernel, and (2) an unprotected
user-mode heap for use by applications. If you are only interested
in protected the kernel from read access, then this option is not
necessary. If you wish to secure the kernel data as well, then
this option should be selected.
Under Flat build, this option will enable a separate heap for the kernel.
By separating the kernel and userspace heaps, the user is granted more
control over the heaps placement within the memory hierarchy, which is
specially useful for microcontrollers that provide External RAM.
Besides segregating the kernel and userspace allocations, this feature
does not prevent the userspace from accessing the kernel heap.
As for Protected and Kernel builds, this feature partitions heap memory
into two parts:
(1) a protected, kernel-mode heap accessible only by the NuttX kernel,
and (2) an unprotected user-mode heap for use by applications.
If you are only interested in protecting the kernel from read access,
then this option is not necessary. If you wish to secure the kernel data
as well, then this option should be selected.
The kernel heap size that is used is provided a a platform-specific
up_allocate_kheap() interface. This configuration setting is made
mm/umm_heap/umm_initialize.c
+4 -2
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@@ -43,8 +43,10 @@
*
* CONFIG_BUILD_FLAT:
* There is only kernel mode "blob" containing both kernel and
* application code. There is only one heap that is used by both the
* kernel and application logic.
* application code. Depending upon the setting of CONFIG_MM_KERNEL_HEAP
* there may be a single shared heap (used by both the kernel and
* application logic) or there may be separate (although unprotected)
* kernel and user heaps.
*
* In this configuration, this function is called early in nx_start()
* to initialize the common heap.