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comparison cos/kernel/goto64.asm @ 35:bcb3b68c8147

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Added bss end address and load end address to multiboot header
author windel
date Mon, 16 Jan 2012 17:38:00 +0100
parents 8012221dd740
children
comparison
equal deleted inserted replaced
34:8012221dd740 35:bcb3b68c8147
34 MultiBootHeader: 34 MultiBootHeader:
35 dd MAGIC 35 dd MAGIC
36 dd FLAGS 36 dd FLAGS
37 dd CHECKSUM 37 dd CHECKSUM
38 ; item below are present if bit 16 is set in flags 38 ; item below are present if bit 16 is set in flags
39 dd MultiBootHeader ; physical address in file of header (will be 0x100000 if put at start) 39 extern load_end_address ; Import load end address from linker script
40 dd 0x100000 ; load_addr: load address, the address to start loading 40 extern bss_end_address ; Import bss end address to make sure data is zero initialized.
41 dd 0x0 ; load_end_addr: zero indicates to load whole file 41 dd MultiBootHeader ; physical address in file of header (will be 0x100000 if put at start)
42 dd 0x0 ; bss_end_addr: zero indicates no bss segment present 42 dd 0x100000 ; load_addr: load address, the address to start loading
43 dd loader ; entry_addr: jump to here 43 dd load_end_address ; load_end_addr: zero indicates to load whole file
44 dd bss_end_address ; bss_end_addr: zero indicates no bss segment present
45 dd loader ; entry_addr: jump to here
44 46
45 ; 32 bits temporary GDT: 47 ; 32 bits temporary GDT:
46 align 16 48 align 16
47 gdt32: 49 gdt32:
48 dw 0x0000, 0x0000, 0x0000, 0x0000 ; Null desciptor 50 dw 0x0000, 0x0000, 0x0000, 0x0000 ; Null desciptor
93 db "Long mode not supported", 0x0 95 db "Long mode not supported", 0x0
94 96
95 ; Start of loader code: 97 ; Start of loader code:
96 loader: 98 loader:
97 ; here ebx contains the pointer to the multiboot header, store is for later use. 99 ; here ebx contains the pointer to the multiboot header, store is for later use.
100 ; Make sure that multiboot_info is located in the BSS section and that this section
101 ; is proper zeroed.
98 extern multiboot_info 102 extern multiboot_info
99 mov [multiboot_info], ebx 103 mov [multiboot_info], ebx
100 xor ebx, ebx
101 mov [multiboot_info + 4], ebx ; zero the rest of 64 bits address.
102 104
103 ; Check that the CPU supports long mode: 105 ; Check that the CPU supports long mode:
104 mov eax, 80000000h 106 mov eax, 80000000h
105 cpuid 107 cpuid
106 cmp eax, 80000000h 108 cmp eax, 80000000h