Better documentation of {k,p}{malloc,free}() functions

This commit is contained in:
Steffen Vogel 2016-03-04 15:03:06 +01:00
parent 5c63d9cb54
commit 3cf7888fea

View file

@ -47,37 +47,55 @@ extern "C" {
/** @brief General page allocator function /** @brief General page allocator function
* *
* This function allocates and maps whole pages. * This function allocates and maps whole pages.
* To avoid fragmentation you should use kmalloc() and kfree()! * Mapped memory will be tracked by the VMA subsystem.
* The sz argument is rounded down to multiples of the page size.
*
* For allocations which are smaller than a page you should use
* the buddy system allocator (kmalloc and kfree) to avoid fragmentation.
* *
* @param sz Desired size of the new memory * @param sz Desired size of the new memory
* @param flags Flags to for map_region(), vma_add() * @param flags Flags to for map_region(), vma_add()
* *
* @return Pointer to the new memory range * @return Pointer to the new memory range (page-aligned).
*/ */
void* palloc(size_t sz, uint32_t flags); void* palloc(size_t sz, uint32_t flags);
/** @brief Free general kernel memory /** @brief Free general kernel pages
*
* This function removes the memory from the VMA subsystem,
* unmap the pages and releases the physical pages.
* *
* The pmalloc() doesn't track how much memory was allocated for which pointer, * The pmalloc() doesn't track how much memory was allocated for which pointer,
* so you have to specify how much memory shall be freed. * so you have to specify how much memory shall be freed.
* *
* @param addr The virtual address returned by palloc().
* @param sz The size which should freed * @param sz The size which should freed
*/ */
void pfree(void* addr, size_t sz); void pfree(void* addr, size_t sz);
/** @brief The memory allocator function /** @brief The memory allocator function
* *
* This allocator uses a buddy system to manage free memory. * This allocator uses a buddy system to allocate memory.
* Attention: memory is not aligned!
* *
* @return Pointer to the new memory range * @return Pointer to the new memory range
*/ */
void* kmalloc(size_t sz); void* kmalloc(size_t sz);
/** @brief The memory free function /** @brief Release memory back to the buddy system
* *
* Releases memory allocated by malloc() * Every block of memory allocated by kmalloc() is prefixed with a buddy_t
* which includes the the size of the allocated block.
* This prefix is also used to re-insert the block into the linked list
* of free buddies.
* *
* @param addr The address to the memory block allocated by malloc() * Released memory will still be managed by the buddy system.
* Pages are not unmapped.
*
* Note: adjacent buddies are currently not merged!
*
* @see buddy_t
* @param addr The address to the memory block allocated by kmalloc()
*/ */
void kfree(void* addr); void kfree(void* addr);