haiku/headers/private/kernel/arch/m68k/arch_mmu.h
François Revol 5da61ace79 - 040 mmu descriptors, FIXME
- remove unneeded include to make those usable by bootloader.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26117 a95241bf-73f2-0310-859d-f6bbb57e9c96
2008-06-23 23:15:43 +00:00

124 lines
3.3 KiB
C

/*
** Copyright 2003, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
** Distributed under the terms of the OpenBeOS License.
*/
#ifndef _KERNEL_ARCH_M68K_MMU_H
#define _KERNEL_ARCH_M68K_MMU_H
#include <SupportDefs.h>
#include <string.h>
/*
* cf.
* "mc68030 Enhanced 32-bit Microprocessor User's Manual"
* (3rd edition), Section 9
* "mc68040 Enhanced 32-bit Microprocessor User's Manual"
* Section 9
*
* The 030 pmmu can support up to 6-level translation tree,
* each level using an size-selectable index from the
* virtual address, short (4-bit) and long (8-bit) page table
* and page entry descriptors, early tree termination, and selectable
* page size from 256 bytes to 32K.
* There is optionally a separate Supervisor Root Pointer to separate
* the user and kernel trees.
*
* The 040 pmmu however is way more limited in its abilities.
* It has a fixed 3-level page tree, with 7/7/6 bit splitting for
* 4K pages. The opcodes are also different so we will need specific
* routines. Both supervisor and root pointers must be used so we can't
* reuse one of them.
*
*
* We settle to:
* - 1 bit index for the first level to easily split kernel and user
* part of the tree, with the possibility to force supervisor only for
* the kernel tree. The use of SRP to point to a 2nd tree is avoided as
* it is not available on 68060, plus that makes a spare 64bit reg to
* stuff things in.
* - 9 bit page directory
* - 10 bit page tables
* - 12 bit page index (4K pages, a common value).
*/
enum descriptor_types {
DT_INVALID = 0, // invalid entry
DT_PAGE, // page descriptor
DT_VALID_4, // short page table descriptor
DT_VALID_8, // long page table descriptor
};
#if 0
/* This is the normal layout of the descriptors, as per documentation.
* When page size > 256, several bits are unused in the LSB of page
* addresses, which we can use in addition of other unused bits.
* the structs dedlared later reflect this for 4K pages.
*/
struct short_page_directory_entry {
// upper 32 bits
uint32 type : 2;
uint32 write_protect : 1;
uint32 used : 1;
uint32 address : 28;
};
struct long_page_directory_entry {
// upper 32 bits
uint32 type : 2;
uint32 write_protect : 1;
uint32 used : 1;
uint32 _zero1 : 4;
uint32 supervisor : 1;
uint32 _zero2 : 1;
uint32 _ones : 6;
uint32 limit : 15;
uint32 low_up : 1; // limit is lower(1)/upper(0)
// lower 32 bits
uint32 unused : 4; //
uint32 address : 28;
};
struct short_page_table_entry {
uint32 type : 2;
uint32 write_protect : 1;
uint32 used : 1;
uint32 modified : 1;
uint32 _zero1 : 1;
uint32 cache_inhibit : 1;
uint32 _zero2 : 1;
uint32 address : 24;
};
struct long_page_table_entry {
// upper 32 bits
uint32 type : 2;
uint32 write_protect : 1;
uint32 used : 1;
uint32 modified : 1;
uint32 _zero1 : 1;
uint32 cache_inhibit : 1;
uint32 _zero2 : 1;
uint32 supervisor : 1;
uint32 _zero3 : 1;
uint32 _ones : 6;
// limit only used on early table terminators, else unused
uint32 limit : 15;
uint32 low_up : 1; // limit is lower(1)/upper(0)
// lower 32 bits
uint32 unused : 8; //
uint32 address : 24;
};
#endif
/* ppc
extern void m68k_get_page_table(page_table_entry_group **_pageTable, size_t *_size);
extern void m68k_set_page_table(page_table_entry_group *pageTable, size_t size);
*/
#endif /* _KERNEL_ARCH_M68K_MMU_H */