/* Copyright (C) 2005  David Decotigny
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 #ifndef _SOS_MMCTXT_H_
 #define _SOS_MMCTXT_H_
 
 
 /**
  * @file mm_context.h
  *
  * Low level API to manage multiple MMU translation tables. The API
  * (not its implementation) should be some kind of
  * architecture-independent.
  *
  * The goal of this API is:
  *   - To provide a simple arch-independent API to change the current
  *     address space configured in the MMU
  *   - To make sure that ALL the kernel space mappings are always kept
  *     IDENTICAL among all the address spaces in the whole system. That
  *     way, a virtual address in the kernel space refers to EXACTLY the
  *     same physical memory location for all the address spaces.
  */
 
 #include <sos/types.h>
 #include <sos/errno.h>
 
 
 /**
  * Declaration of an MMU context. Opaque structure defined in
  * mm_context.c
  */
 struct sos_mm_context;
 
 
 /**
  * Setup the MMU context management subsystem
  */
 sos_ret_t sos_mm_context_subsystem_setup();
 
 
 /**
  * Public function to allocate a new MMU context.
  *
  * Allocate a new PD, map it into kernel virtual address space and
  * initialize its PDE for the Kernel space so that the Kernel space is
  * kept identical between ALL the MMU context in the system.
  */
 struct sos_mm_context * sos_mm_context_create(void);
 
 
 /**
  * Public function to create a new MMU context, copy of another one.
  *
  * Allocate a new PD, map it into kernel virtual address space,
  * initialize its PDE for the Kernel space so that the Kernel space is
  * kept identical between ALL the MMU context in the system and copy
  * the PDE/PT of the user space to match that of the model mm_context.
  */
 struct sos_mm_context *
 sos_mm_context_duplicate(const struct sos_mm_context *model);
 
 
 /**
  * Public function to release the given MMU context (based on
  * reference counting). Only the virtual page that maps the PD of the
  * MMU context is released. All the other user-space pages are
  * expected to be already released by the parent process.
  */
 sos_ret_t sos_mm_context_unref(struct sos_mm_context *mmctxt);
 
 
 /**
  * Reconfigure the MMU to use a different MMU context. mmctxt MUST
  * NOT be NULL.
  */
 sos_ret_t sos_mm_context_switch_to(struct sos_mm_context *mmctxt);
 
 
 /* ******************************************************
  * Reserved functions
  */
 
 
 /**
  * Reserved function to increase the reference count of the given MMU
  * context (based on reference counting).
  */
 sos_ret_t sos_mm_context_ref(struct sos_mm_context *mmctxt);
 
 
 /**
  * Restricted function reserved to paging.c to synchronize all the PDEs
  * accross all the MMU contexts in the system. This is limited to PDEs
  * pertaining to the kernel space.
  */
 sos_ret_t sos_mm_context_synch_kernel_PDE(unsigned int index_in_pd,
                                           sos_ui32_t pde);
 
 #endif /* _SOS_MMCTXT_H_ */