mm: Remove mm_heap_impl_s struct

[xiaoxiang781216]

Summary

since it's more simple to make mm_heap_s opaque outside of mm

Impact

mm_heap_s become opaque struct

Testing

ostest

[davids5]

@xiaoxiang781216 I just noticed that the change adding the name is not reflected in the mm/README.txt nor the titale blocks

/****************************************************************************
 * Name: mm_initialize
 *
 * Description:
 *   Initialize the selected heap data structures, providing the initial
 *   heap region.
 *
 * Input Parameters:
 *   heap      - The selected heap
 *   heapstart - Start of the initial heap region
 *   heapsize  - Size of the initial heap region
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *
 ****************************************************************************/

[davids5]

@xiaoxiang781216 -

This looks good.

[Ouss4]

Suggested change

	/* Initialize the user heap if not yet */
	umm_try_initialize();
	/* Initialize the user heap if it wasn't yet. */
	umm_try_initialize();

Why is this required here?

[xiaoxiang781216]

Kernel mode doesn't call umm_initialize in nx_start(it's impossible from technique since each process has a dedicated heap instance). Before this patch, sbrk will initialize the heap when malloc fail first time and fallback to sbrk, but we have to initialize explicitly here because tg_heap change to pointer and then no place to save the flag before we let g_heap point to some memory.

[xiaoxiang781216]

the comment is fixed, @Ouss4

[Ouss4]

Thanks for the explanation!

[xiaoxiang781216]

@xiaoxiang781216 I just noticed that the change adding the name is not reflected in the mm/README.txt nor the titale blocks

/****************************************************************************
 * Name: mm_initialize
 *
 * Description:
 *   Initialize the selected heap data structures, providing the initial
 *   heap region.
 *
 * Input Parameters:
 *   heap      - The selected heap
 *   heapstart - Start of the initial heap region
 *   heapsize  - Size of the initial heap region
 *
 * Returned Value:
 *   None
 *
 * Assumptions:
 *
 ****************************************************************************/

Done.

[Ouss4]

LGTM.