Date: Wed, 21 Mar 2001 23:29:41 +0600 (NOVT) From: Alexey Dokuchaev <danfe@inet.ssc.nsu.ru> To: freebsd-hackers@freebsd.org Subject: Linux -> FreeBSD VM functions Message-ID: <Pine.LNX.4.10.10103212233240.22100-100000@inet.ssc.nsu.ru> In-Reply-To: <Pine.LNX.4.10.10103190158060.7285-100000@inet.ssc.nsu.ru>
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Hello!
I seems to have a lot of VM-relevant code to port, and I'd like to get
answers for several questions arised along the way:
---
* How do I port something like this:
<code ostype="linux">
. . .
static inline unsigned long
get_kvirt_address(unsigned long address)
{
pgd_t *pg_dir;
pmd_t *pg_mid_dir;
pte_t *pg_table;
unsigned long ret_addr = 0;
pg_dir = pgd_offset(current->mm, address);
if (pgd_none(*pg_dir))
goto done;
pg_mid_dir = pmd_offset(pg_dir, address);
if (pmd_none(*pg_mid_dir))
goto done;
pg_table = pte_offset(pg_mid_dir, address);
if (!pte_present(*pg_table))
goto done;
ret_addr = pte_page(*pg_table);
done:
return ret_addr;
}
. . .
</code>
Is simple PHYS_TO_VM_PAGE will do?
---
* What about this one:
<code ostype="linux">
. . .
if (PageReserved(mem_map + GET_MAP_NR(page))) { ... }
. . .
</code>
And this one:
<code ostype="linux">
. . .
mem_map_reserve(GET_MAP_NR(page));
. . .
</code>
---
* There seem to be these flags defined in linux/mm.h:
<code ostype="linux">
/* 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
</code>
How do those relate to FreeBSD vision of things?
---
I will really appreciate any help with regard to this, since this is my
first serious in-depth look at VM internals of both linux and FreeBSD, and
there seem to be no technical (that is, not plain overviews) of both VM
subsystems.
--
Regs,
Alexey
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