Date: Tue, 31 Jul 2001 15:38:54 -0600 From: "Weiguang SHI" <weiguang_shi@hotmail.com> To: freebsd-hackers@freebsd.org Subject: address resolution question Message-ID: <F1950ZDbz006MLqNbdV0000a502@hotmail.com>
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Hi,
I need your help to understand this.
In machdep.c,
1451 /*
1452 * map page 1 R/W into the kernel page table so we can use
it
1453 * as a buffer. The kernel will unmap this page later.
1454 */
1455 pte = (pt_entry_t)vtopte(KERNBASE + (1 <<PAGE_SHIFT));
1456 *pte = (1 << PAGE_SHIFT) | PG_RW | PG_V;
According to my calculation, pte=0xbfcc0001 and *pte will yield
0x2FF,0xC0,0x1 as indexes to the page directory table, page table and
an offset. My page directory table is like this (starting at physical
address 0x2C2000):
index page_table_base_address; prot
---------- -----------------------------
0,0x1D 0x2A4,0x2C1 ; RW
0x2FF 0x2C2 ; RW
0x300,0x31D 0x2A4,0x2C1 ; RW
The entries that are not listed are all zeros. This table was created
by "create_pagetable" in locore.s
I know there is a recursive reference, i.e., the 0x2ff entry. But I
need more (authoritative) explanation on how the triple
(0x2ff,0xc0,0x1) is going to be resolved.
Would you shed some light?
Thanks very much.
Weiguang
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