FreeBSD/Linux Kernel Cross Reference
sys/vm/phys_pager.c

     /*
      * (MPSAFE)
      *
      * Copyright (c) 2000 Peter Wemm
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: src/sys/vm/phys_pager.c,v 1.3.2.3 2000/12/17 02:05:41 alfred Exp $
     */
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/linker_set.h>
    #include <sys/conf.h>
    #include <sys/mman.h>
    #include <sys/sysctl.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    #include <vm/vm_zone.h>
    
    #include <sys/thread2.h>
    #include <vm/vm_page2.h>
    
    /*
     * No requirements.
     */
    vm_object_t
    phys_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
    {
            vm_object_t object;
    
            /*
             * Offset should be page aligned.
             */
            if (foff & PAGE_MASK)
                    return (NULL);
    
            size = round_page64(size);
    
            KKASSERT(handle == NULL);
            object = vm_object_allocate(OBJT_PHYS, OFF_TO_IDX(foff + size));
    
            return (object);
    }
    
    /*
     * No requirements.
     */
    static void
    phys_pager_dealloc(vm_object_t object)
    {
            KKASSERT(object->handle == NULL);
            KKASSERT(object->swblock_count == 0);
    }
    
    /*
     * No requirements.
     */
    static int
    phys_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
    {
            vm_page_t m = *mpp;
    
            if ((m->flags & PG_ZERO) == 0)
                    vm_page_zero_fill(m);
            vm_page_flag_set(m, PG_ZERO);
            /* Switch off pv_entries */
            vm_page_unmanage(m);
            m->valid = VM_PAGE_BITS_ALL;
            m->dirty = VM_PAGE_BITS_ALL;
    
            return (VM_PAGER_OK);
    }
    
    /*
     * No requirements.
     */
    static void
   phys_pager_putpages(vm_object_t object, vm_page_t *m, int count,
                       boolean_t sync, int *rtvals)
   {
   
           panic("phys_pager_putpage called");
   }
   
   /*
    * Implement a pretty aggressive clustered getpages strategy.  Hint that
    * everything in an entire 4MB window should be prefaulted at once.
    *
    * XXX 4MB (1024 slots per page table page) is convenient for x86,
    * but may not be for other arches.
    */
   #ifndef PHYSCLUSTER
   #define PHYSCLUSTER 1024
   #endif
   
   /*
    * No requirements.
    */
   static boolean_t
   phys_pager_haspage(vm_object_t object, vm_pindex_t pindex)
   {
           return (TRUE);
   }
   
   struct pagerops physpagerops = {
           phys_pager_dealloc,
           phys_pager_getpage,
           phys_pager_putpages,
           phys_pager_haspage
   };

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