[Stormdos-develop] mem.txt - memory management in SD-32

[Juras <yb...@tu...>]

Hello stormdos-develop,

New version:

Memory management in SD-32
~~~~~~~~~~~~~~~~~~~~~~~~~~
Designed with the usage of page translation mode of IA-32.


1) one list of free physical memory blocks
 - the lowest layer
 

2) one list
 [0, 80000000h) - shared addresses, "global memory" which points
  to the same physical addresses in address spaces of every
  context. This memory is allocated by the kernel for the kernel and
  drivers use (maps video memory, keep system structures and everything
  which must be accessed by the kernel being run withing the address
  space of a context...)
  
  
3) per application (application has threads which share the same address space)
  list of free virtual addresses in the range of
  [80000000h, C0000000) - memory used by process (application), i.e. 
  where the executable image is loaded and relocated.
  
  
4) one list of free virtual addresses in the range of
  [C0000000, FFFFFFFF] - addresses for DLLs. We need this region separated
  because when any application loads a DLL we must provide the ability
  for the rest of applications running or which will be run later to
  use the same addresses for the same DLL attached to a new process.
  
  
  
Memory maps for 3) and 4) map their SHARED and READ-ONLY sections to
the same physical addresses (like in MS Windows).


FUNCTIONS
~~~~~~~~~

AllocPhysical - allocates only continuous blocks
ReallocPhysical - reallocates only continuous blocks
FreePhysical




AllocVirtual - allocates only addresses (continuous)
ReallocVirtual
FreeVirtual


MapAddresses - uses allocated page dir to map addresses to physical

DisableAddresses - uses allocated page dir to mark pages as unpresent.


AllocVirtualPhys - allocates physical memory and virtual addresses
                   and modifies page directory.
                   underlying physical memory may be
                   fragmented.
                   
                   
ReallocVirtualPhys - underlying physical memory may be fragmented
FreeVirtualPhys
  

-- 
Best regards,
 Juras                          mailto:yb...@tu...