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Allow vm_page_array to have holes in it so systems that use 

MACHINE_NONCONTIG can use a fast, simple pmap_page_index().
This commit is contained in:
gwr 1994-12-01 00:19:57 +00:00
parent 9d831a17b7
commit 0a0c02cd38
1 changed files with 55 additions and 23 deletions
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78
sys/vm/vm_page.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vm_page.c,v 1.20 1994/10/30 19:11:20 cgd Exp $ */
/* $NetBSD: vm_page.c,v 1.21 1994/12/01 00:19:57 gwr Exp $ */
/*
* Copyright (c) 1991, 1993
@ -492,39 +492,71 @@ pmap_startup(startp, endp)
vm_offset_t *startp;
vm_offset_t *endp;
{
unsigned int i;
unsigned int i, pmap_idx, freepages;
vm_offset_t paddr;
/*
* We calculate how many page frames we will have
* and then allocate the page structures in one chunk.
* We calculate how many page frames we will have
* and then allocate the page structures in one chunk.
* The calculation is non-trivial. We want:
*
* vmpages > (freepages - (vmpages / sizeof(vm_page_t)))
*
* which, with some algebra, becomes:
*
* vmpages > (freepages * sizeof(...) / (1 + sizeof(...)))
*
* The value of vm_page_count need not be exact, but must be
* large enough so vm_page_array handles the index range.
*/
vm_page_count = ((PAGE_SIZE * pmap_free_pages() +
(round_page(virtual_space_start) - virtual_space_start)) /
(PAGE_SIZE + sizeof *vm_page_array));
vm_page_array = (vm_page_t) pmap_steal_memory(vm_page_count
* sizeof *vm_page_array);
freepages = pmap_free_pages();
/* Fudge slightly to deal with truncation error. */
freepages += 1; /* fudge */
vm_page_count = (PAGE_SIZE * freepages) /
(PAGE_SIZE + sizeof(*vm_page_array));
vm_page_array = (vm_page_t)
pmap_steal_memory(vm_page_count * sizeof(*vm_page_array));
#ifdef DIAGNOSTIC
/*
* Initialize everyting in case the holes are stepped in,
* and set PA to something that will cause a panic...
*/
for (i = 0; i < vm_page_count; i++) {
bzero(&vm_page_array[i], sizeof(*vm_page_array));
vm_page_array[i].phys_addr = 0xdeadbeef;
}
#endif
/*
* Initialize the page frames.
* Note that some page indices may not be usable
* when pmap_free_pages() counts pages in a hole.
*/
for (i = 0; i < vm_page_count; i++) {
if (!pmap_next_page(&paddr))
break;
if (!pmap_next_page(&paddr))
panic("pmap_startup: can't get first page");
first_page = pmap_page_index(paddr);
i = 0;
for (;;) {
/* Initialize a page array element. */
VM_PAGE_INIT(&vm_page_array[i], NULL, NULL);
vm_page_array[i].phys_addr = paddr;
vm_page_free(&vm_page_array[i]);
/* Are there more physical pages? */
if (!pmap_next_page(&paddr))
break;
pmap_idx = pmap_page_index(paddr);
i = pmap_idx - first_page;
/* Don't trust pmap_page_index()... */
if (i < 0 || i >= vm_page_count)
panic("pmap_startup: bad i=0x%x", i);
}
/*
* Remember the actual page count and the index of the first page
*/
vm_page_count = i;
first_page = pmap_page_index(vm_page_array[0].phys_addr);
*startp = virtual_space_start;
*endp = virtual_space_end;
}