mmio.c

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/* $Id: mmio.c,v 1.5 2003/08/29 10:13:22 ch12 Exp $ */
/*****************************************************************************/
/* (c) 2003 Technische Universitaet Dresden
 * This file is part of DROPS, which is distributed under the terms of the
 * GNU General Public License 2. Please see the COPYING file for details.
 */

/* L4 */
#include <l4/env/errno.h>
#include <l4/sys/types.h>

#include <l4/dde_linux/dde.h>

/* Linux */
#include <linux/mm.h>

/* local */
#include "__config.h"

int remap_page_range(unsigned long virt_addr,
                     unsigned long phys_addr, unsigned long size, pgprot_t prot)
{
  return -ENOMEM;
}

/* mmap() / remap_page_range() / vm_area_struct.nopage() discussion

   (mostly from Rubini: Linux Device Drivers)

   - logical addresses are not available for high memory. thus kernel functions
   that deal with memory are increasingly using pointers to "struct page"
   instead.

   - "struct page" includes a "void *virtual" member (low memory is always
   mapped high memory not)

     - kernel virtual address of the page or

     - NULL if not mapped

   - virt_to_page() return "struct page" associated to logical address

   - page_address() return virtual addres of "struct page"

   - kmap() return virtual address of any page (if not mapped mapping is done
   before return)

   - kunmap() frees special kmap() mappings

   - virtual memory areas (vma) is a higher-level mechanism to handle the way a
   process sees its memory

   - a driver that implements mmap() needs to fill a vma structure in the
   address space of the process mapping the device

   - "struct vm_area_struct"

   - "struct vm_operations_struct"
     ... open/close/unmap/protect/sync/nopage/swapout

   -

 */

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