From owner-freebsd-hackers  Wed Mar 21 14:41: 8 2001
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Date: Wed, 21 Mar 2001 14:44:31 -0800
From: Chris Sears <cbsears@ix.netcom.com>
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To: Alexey Dokuchaev <danfe@inet.ssc.nsu.ru>
Cc: freebsd-hackers@freebsd.org
Subject: Re: Linux -> FreeBSD VM functions
References: <Pine.LNX.4.10.10103212233240.22100-100000@inet.ssc.nsu.ru>
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Alexey

>         static inline unsigned long
>         get_kvirt_address(unsigned long address)
>         {
>         }

This function returns 0 if a virtual address is not mapped.
Otherwise it returns the linear address associated
with that virtual address by traversing the page table
and extracting the physical address from mem_map,
the reverse-mapped software pagetable.

>         Is simple PHYS_TO_VM_PAGE will do?

No actually it would the other way around: VM_PAGE_TO_PHYS.
But you have to get the vm_page of the virtual address first.
Perhaps pmap_extract(pmap, va) might be more helpful
but you will need the pmap of the process.

> if (PageReserved(mem_map + GET_MAP_NR(page))) { ... }

PG_reserved means that the page is reserved to the kernel.
*Maybe* PG_UNMANAGED might be analogous.

> 
> /* Page flag bit values */
> #define PG_locked                0
> #define PG_error                 1
> #define PG_referenced            2
> #define PG_dirty                 3
> #define PG_uptodate              4
> #define PG_free_after            5
> #define PG_decr_after            6
> #define PG_swap_unlock_after     7
> #define PG_DMA                   8
> #define PG_Slab                  9
> #define PG_swap_cache           10
> #define PG_skip                 11
> #define PG_reserved             31
> 
>         How do those relate to FreeBSD vision of things?

Look at vm_page.h

You should spend some quality time with Understanding the Linux Kernel
especially chapter 6, and/or the Linux Commentary.  And chapter 5
of Design and Implementation of 4.4BSD.  And since the 4.4BSD vm
is really the Mach vm you should look at that stuff too.

Chris

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