diff options
Diffstat (limited to 'arch/i386/paging.h')
| -rw-r--r-- | arch/i386/paging.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/arch/i386/paging.h b/arch/i386/paging.h new file mode 100644 index 0000000..f5bfa78 --- /dev/null +++ b/arch/i386/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; +}; +/* TODO _Static_assert(sizeof(struct DirectoryEntry) == 4, "DirectoryEntry size"); */ + +/* 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; +}; +/* TODO _Static_assert(sizeof(struct DirectoryEntry4MB) == 4, "DirectoryEntry4M size"); */ + +/* 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; +}; +/* TODO _Static_assert(sizeof(struct TableEntry) == 4, "TableEntry size"); */ |