=================
Memory management
=================

A frame is a fixed-sized block of physical memory. A page is a fixed-size block of virtual memory. Both are of the same size (4kB).

Physical memory allocator
=========================
The FrameAllocator takes a bitmap describing available physical memory and allocates free frames. There is one global
instance.

Virtual memory allocator
========================
The PageAllocator takes allocated Frames and mounts them in virtual memory.

.. table:: Virtual address space layout
   :widths: auto

   ============== ==================== ===========
   address        symbol               description
   ============== ==================== ===========
   ``ffff ffff``                       virtual memory end
   ``d000 0000``                       MMIO
   ``c040 0000``                       kernel allocator
   page-aligned   ``__data_begin``    
   page-aligned   ``__bss_begin``     
   page-aligned   ``__rodata_begin``  
   ``c000 0000``  ``__text_begin``     kernel text
   ``0000 0000``                       virtual memory start
   ============== ==================== ===========

.. include:: mem/constinit.rst