docs: documents memory management
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@ -81,6 +81,8 @@ Group: Kernel {
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} # Group: Sys
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File: vm.inc (kernel/vm/vm.inc)
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File: pmap.s (kernel/vm/pmap.s)
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} # Group: Kernel
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Group: Lib {
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89
docs/img/pmap_bootstrap.mmd
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89
docs/img/pmap_bootstrap.mmd
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@ -0,0 +1,89 @@
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---
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title: pmap_bootstrap
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---
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flowchart TD
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R_BEGIN("Begin")
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R_GETMMAP["Get Memory Map entry"]
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R_MMAP_LAST{"Last Item ?"}
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R_END("End")
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subgraph "entry to pmap_block"
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C_BEGIN("Begin Proc")
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C_IS_FREE{"Is
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entry free?"}
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C_END("End Proc")
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C_OVERLAP_KERNEL{"entry
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overlap
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kernel?"}
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C_REMOVE_KRESERVED["Remove Kernel
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Memory from entry"]
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C_MEMORY_SIZE_EXCEED{"Is entry size
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larger than
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0x0x7f80000 ?"}
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C_MEMORY_SPLIT["Split entry"]
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C_MEMORY_LAST["Is last ?"]
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C_BEGIN-->C_IS_FREE
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C_IS_FREE--No-->C_END
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C_IS_FREE--Yes-->C_OVERLAP_KERNEL
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C_OVERLAP_KERNEL--Yes-->C_REMOVE_KRESERVED
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C_REMOVE_KRESERVED-->C_MEMORY_SIZE_EXCEED
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C_OVERLAP_KERNEL--No-->C_MEMORY_SIZE_EXCEED
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C_MEMORY_SIZE_EXCEED--Yes-->C_MEMORY_SPLIT
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C_MEMORY_SPLIT-->C_MEMORY_LAST
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C_MEMORY_LAST--Yes-->C_END
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end
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subgraph "create & store pmap_block"
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D_BEGIN("Begin Proc")
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D_BOOSTRAP_EXIST{"Bootstrap
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pmap_block
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exist?"}
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D_SETUP_BOOTSTRAP["Setup bootstrap pmap"]
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D_END("End Proc")
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D_SET_HEAD_BOOTSTRAP["Set bootstrap as Head"]
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D_SEARCH_FREE_PAGE["Search free page in Head->bitmap"]
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D_FREE_PAGE_FOUND{"Free Page found ?"}
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D_HEAD_NEXT_NULL{"Head->next == NULL?"}
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D_HEAD_NEXT["Set Head to Head->next"]
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D_CREATE_PMAP["Create new pmap_block
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in free page"]
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D_APPEND_PMAP["Append pmap_block
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at end of
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linked list"]
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D_BEGIN-->D_BOOSTRAP_EXIST
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D_BOOSTRAP_EXIST--No-->D_SETUP_BOOTSTRAP
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D_SETUP_BOOTSTRAP-->D_END
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D_BOOSTRAP_EXIST--Yes-->D_SET_HEAD_BOOTSTRAP
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D_SET_HEAD_BOOTSTRAP-->D_SEARCH_FREE_PAGE
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D_SEARCH_FREE_PAGE-->D_FREE_PAGE_FOUND
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D_FREE_PAGE_FOUND--No-->D_HEAD_NEXT_NULL
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D_HEAD_NEXT_NULL--No-->D_HEAD_NEXT
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D_HEAD_NEXT-->D_SEARCH_FREE_PAGE
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D_FREE_PAGE_FOUND--Yes-->D_CREATE_PMAP
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D_CREATE_PMAP-->D_APPEND_PMAP
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D_APPEND_PMAP-->D_END
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end
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R_BEGIN-->R_GETMMAP
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R_GETMMAP-->R_MMAP_LAST
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R_MMAP_LAST--Yes-->R_END
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R_MMAP_LAST--No-->C_BEGIN
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C_MEMORY_SIZE_EXCEED--No-->D_BEGIN
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D_END--Try get next-->C_MEMORY_LAST
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C_MEMORY_LAST--No-->D_BEGIN
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C_END--Try get next entry-->R_MMAP_LAST
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style R_BEGIN fill:#6CA300
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style R_END fill:#A30000
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style C_BEGIN fill:#6CA300
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style C_END fill:#A30000
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style D_BEGIN fill:#6CA300
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style D_END fill:#A30000
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BIN
docs/img/pmap_bootstrap.png
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BIN
docs/img/pmap_bootstrap.png
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Binary file not shown.
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After Width: | Height: | Size: 122 KiB |
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@ -7,4 +7,4 @@ INCS = sys/multiboot.inc \
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sys/i386/registers.inc
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include $(TOPDIR)/share/mk/stupid.kernel.mk
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include $(TOPDIR)/share/mk/stupid.inc.mk
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#include $(TOPDIR)/share/mk/stupid.inc.mk
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@ -1,7 +1,46 @@
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;; File: mmu.inc
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;;
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;; About: Address Translation
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;;
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;; Since we don't use segmentation, this is how address translation works
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;; > 31 21 11 0
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;; > +--------+--------+--------+
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;; > | DIR | PAGE | OFFSET |
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;; > +--------+--------+--------+
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;; > |
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;; > v
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;; > Page Translation
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;; > |
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;; > 31 v 0
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;; > +--------------------------+
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;; > | Pyshical address |
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;; > +--------------------------+
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;;
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;; About: Page Translation
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;;
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;; > +--------+--------+--------+ +--------+
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;; > | DIR | PAGE | OFFSET |-----+ | Phys |
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;; > +--------+--------+--------+ +------>| addr |
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;; > | | | |
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;; > | +----+ +--------+
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;; > | Page Dir | +---> Page Frame
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;; > | +---------+ | +--------+ |
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;; > | | | | | | |
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;; > +->| PDE |-+ +->| PTE |-+
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;; > | | | | |
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;; > +---------+ | +--------+
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;; > +----> Page Table
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;; >
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;;
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;; Macro: V2P(addr)
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;; Convert Kernel Address to Physical Address
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%define V2P(addr) (addr - KERNBASE)
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;; Macro: P2V(addr)
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;; Convert Physical Address to Kernel Address
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%define P2V(addr) (addr + KERNBASE)
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%define P2PDE(addr) ((addr >> 22) & 0x3FF)
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%define PDE2P(addr) (addr << 22)
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%define P2PTE(addr) ((addr >> 12) & 0x3FF)
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@ -26,8 +65,8 @@ PDE_G equ 1 << 8
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;; PTE_PCD - Cache Disable
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;; PTE_A - Accessed
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;; PTE_D - Dirty
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;; PTE_PAT -
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;; PTE_G -
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;; PTE_PAT - TODO
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;; PTE_G - TODO
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PTE_P equ 1 << 0
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PTE_W equ 1 << 1
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PTE_U equ 1 << 2
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46
kernel/vm/pmap.s
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46
kernel/vm/pmap.s
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;; File: pmap.s
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;; Physical Memory Map
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;; Structure: pmap_block
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;;
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;; .next - pointer to next pmap_block struct
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;; .phys_start - start physical address of memory range
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;; .phys_end - stop address of memory range
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;; .bitmap_size - bitmap size (max: 0xFF0)
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;; .last_alloc - last allocated frame in bitmap
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;; .bitmap - bitmap array
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;;
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;; > pmap_block
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;; > 0x0000 +-------------+
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;; > | next |-----> pmap_block
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;; > 0x0004 +-------------+ +----------+
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;; > | phys start | | next |----> NULL (0x0)
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;; > 0x0008 +-------------+ +----------+
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;; > | phys end | | ..... |
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;; > 0x000C +-------------+ | ..... |
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;; > | bitmap size | | ..... |
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;; > 0x000e +-------------+ +----------+
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;; > | last alloc |
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;; > 0x0010 +-------------+
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;; > | bitmap |
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;; > 0x???? +-------------+ (bitmap size * 4)
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;;
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struct pmap_block
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.next: resd 1
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.phys_start: resd 1
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.phys_end: resd 1
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.bitmap_size: resw 1
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.last_alloc: resw 1
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.bitmap:
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endstruc
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section .text
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;; Function: pmap_bootstrap
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;;
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;; (see pmap_bootstrap.png)
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pmap_bootstrap:
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push esp
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mov esp, ebp
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leave
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ret
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60
kernel/vm/vm.inc
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60
kernel/vm/vm.inc
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;; File: vm.inc
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;; Stupid OS virtual Memory manager
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;;
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;; About: Memory Management
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;;
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;; Terminology:
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;; VA - Virtual Address
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;; PA - Physical Address
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;; PDE - Page Directory Entry
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;; PTE - Page Table Entry
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;;
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;; Memory Layout:
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;;
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;; Virtual Memory above `0xC0000000` is mapped as kernel only <PTE_U> flags
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;;
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;; > Virtual
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;; > 0xFFFFFFFF +---------------+
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;; > | |
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;; > | Device Memory |
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;; > | |
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;; > +---------------+
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;; > | |
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;; > | Kernel Heap |
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;; > | |
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;; > KERN_END +---------------+
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;; > | |
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;; > | Stupid Kernel |
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;; > | |
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;; > 0xC0100000 +---------------+
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;; > | I/O Space and |
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;; > | phys memory |
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;; > | Lower than 1M | kernel mode only
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;; > 0xC0000000 +---------------+
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;; > | | user mode
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;; > | userspace |
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;; > | |
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;; > 0x00000000 +---------------+
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;;
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;; Page Frame Allocator
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;;
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%define K2P(addr) (addr - KERNBASE)
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%define P2K(addr) (addr + KERNBASE)
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struc vm_kmap
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.virt: resd 1
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.phys_start: resd 1
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.phys_stop: resd 1
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.access: resb 1
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endstruc
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struc vm_map
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.pmap: resd 1
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endstruc
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struc
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.directory: resd 1
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.ref_count: resd 1
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endstruc
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