From c4fcc92183c55db868d0d6ae53e6009fb2e53ee5 Mon Sep 17 00:00:00 2001 From: aqua Date: Sat, 29 Oct 2022 11:26:44 +0300 Subject: makefile: add i686/arch.a target --- i686/paging.h | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 i686/paging.h (limited to 'i686/paging.h') diff --git a/i686/paging.h b/i686/paging.h new file mode 100644 index 0000000..cff0506 --- /dev/null +++ b/i686/paging.h @@ -0,0 +1,59 @@ +#pragma once + +// DirectoryEntry +// |31| | | | | | | | | | | | | | | | | | | |11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0| +// | page table 4-kb aligned address | avail | G| S| | A| C| W| U| R| P| +struct __attribute__((packed)) DirectoryEntry { + unsigned present : 1; // 0: if set, the page is actually in physical memory + unsigned writeable : 1; // 1: if set, the page is read/write; otherwise the page is read-only + unsigned user : 1; // 2: if set, then page can be access by all; otherwise only the supervisor can access it + unsigned writethrough : 1; // 3: if set, write-through caching is enabled; otherwise write-back is enabled instead + unsigned cachedisable : 1; // 4: if set, the page will not be cached + unsigned accessed : 1; // 5: set by the CPU when the page is read from or written to + unsigned dirty : 1; // 6: used to determine whether a page has been written to + unsigned pagesize : 1; // 7: page size == 0 + unsigned global : 1; + unsigned int __available__ : 3; // available to the OS + unsigned int address : 20; +}; +_Static_assert(sizeof(struct DirectoryEntry) == 4); + +// DirectoryEntry4MB +// |31| | | | | | | | |22|21|20| | | | | | |13|12|11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0| +// | bits 31-22 of address |RS| bits 39-22 of |AT| avail | G|PS| D| A|CD|WT|US|RW| P| +// | |VD| address +struct __attribute__((packed)) DirectoryEntry4MB { + unsigned present : 1; // 0: if set, the page is actually in physical memory + unsigned writeable : 1; // 1: if set, the page is read/write; otherwise the page is read-only + unsigned useraccess : 1; // 2: if set, then page can be access by all; otherwise only the supervisor can access it + unsigned writethrough : 1; // 3: if set, write-through caching is enabled; otherwise write-back is enabled instead + unsigned cachedisable : 1; // 4: if set, the page will not be cached + unsigned accessed : 1; // 5: set by the CPU when the page is read from or written to + unsigned dirty : 1; // 6: used to determine whether a page has been written to + unsigned pagesize : 1; // 7: page size == 1 + unsigned global : 1; // 8: + unsigned __available__ : 3; // 11..9 available to the OS + unsigned pat : 1; // 12: page attribute table + unsigned int address_high : 8; + unsigned rsvd : 1; // 21 + unsigned int address_low : 10; +}; +_Static_assert(sizeof(struct DirectoryEntry4MB) == 4); + +// TableEntry +// |31| | | | | | | | | | | | | | | | | | | |11| | 9| 8| 7| 6| 5| 4| 3| 2| 1| 0| +// | page table 4-kb aligned address | avail | G| | D| A| C| W|US|RW| P| +struct __attribute__((packed)) TableEntry { + unsigned present : 1; // if set, the page is actually in physical memory + unsigned writeable : 1; // if set, the page is read/write; otherwise the page is read-only + unsigned user : 1; // if set, then page can be access by all; otherwise only the supervisor can access it + unsigned writethrough : 1; // if set, write-through caching is enabled; otherwise write-back is enabled instead + unsigned cachedisable : 1; // if set, the page will not be cached + unsigned accessed : 1; // set by the CPU when the page is read from or written to + unsigned dirty : 1; // used to determine whether a page has been written to + unsigned pat : 1; // page attribute table? + unsigned global : 1; + unsigned int __available__ : 3; // available to the OS + unsigned int address : 20; +}; +_Static_assert(sizeof(struct TableEntry) == 4); -- cgit v1.2.1