StupidOS/kernel/sys/mmu.inc

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2024-07-07 13:29:41 +00:00
;; File: mmu.inc
;;
;; About: Address Translation
;;
;; Since we don't use segmentation, this is how address translation works
;; > 31 21 11 0
;; > +--------+--------+--------+
;; > | DIR | PAGE | OFFSET |
;; > +--------+--------+--------+
;; > |
;; > v
;; > Page Translation
;; > |
;; > 31 v 0
;; > +--------------------------+
;; > | Pyshical address |
;; > +--------------------------+
;;
;; About: Page Translation
;;
;; > +--------+--------+--------+ +--------+
;; > | DIR | PAGE | OFFSET |-----+ | Phys |
;; > +--------+--------+--------+ +------>| addr |
;; > | | | |
;; > | +----+ +--------+
;; > | Page Dir | +---> Page Frame
;; > | +---------+ | +--------+ |
;; > | | | | | | |
;; > +->| PDE |-+ +->| PTE |-+
;; > | | | | |
;; > +---------+ | +--------+
;; > +----> Page Table
;; >
;;
;; Defines: Page Directory Flags
;; PDE_P - Present
;; PDE_W - Writable
;; PDE_U - User
;; PDE_PWT - Write-Through
;; PDE_PS - 4MiB page
PDE_P = 0x001
PDE_W = 0x002
PDE_U = 0x004
PDE_PWT = 0x008
PDE_PCD = 0x010
PDE_A = 0x020
PDE_D = 0x040
PDE_PS = 0x080
PDE_G = 0x100
2024-07-07 13:29:41 +00:00
;; Defines: Page Table Flags
;; PTE_P - Present
;; PTE_W - Writable
;; PTE_U - User
;; PTE_PWT - Write-Through
;; PTE_PCD - Cache Disable
;; PTE_A - Accessed
;; PTE_D - Dirty
;; PTE_PAT - TODO
;; PTE_G - TODO
PTE_P = 0x001
PTE_W = 0x002
PTE_U = 0x004
PTE_PWT = 0x008
PTE_PCD = 0x010
PTE_A = 0x020
PTE_D = 0x040
PTE_PAT = 0x080
PTE_G = 0x100