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Rework pmap so that it separates the PTE structure from the pv_entry

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structure. This makes it possible to pre-allocate PTEs for the kernel,
which is necessary for a reliable implementation of pmap_kenter(). This
also avoids wasting space (about 48 bytes per page) for kernel mappings
and user mappings of memory-mapped devices.

This also fixes a bug with the previous version where the implementation
required the pv_entry structure to be physically contiguous but did not
enforce this (the structure size was not a power of two). This meant
that the pv_entry free list was quickly corrupted as soon as the system
was even mildly loaded.
This commit is contained in:
Doug Rabson 2001-10-19 09:47:02 +00:00
parent 0a622d8291
commit 5577bd2bca
2 changed files with 524 additions and 347 deletions
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864
sys/ia64/ia64/pmap.c
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7
sys/ia64/include/pmap.h
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@ -54,6 +54,12 @@
#ifdef _KERNEL
#ifndef NKPT
#define NKPT 30 /* initial number of kernel page tables */
#endif
#define MAXKPT (PAGE_SIZE/sizeof(vm_offset_t))
/*
* Routine: pmap_kextract
* Function:
@ -106,7 +112,6 @@ extern pmap_t kernel_pmap;
* mappings of that page. An entry is a pv_entry_t, the list is pv_table.
*/
typedef struct pv_entry {
struct ia64_lpte pv_pte; /* pte for collision walker */
pmap_t pv_pmap; /* pmap where mapping lies */
vm_offset_t pv_va; /* virtual address for mapping */
TAILQ_ENTRY(pv_entry) pv_list;