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91 lines
1.5 KiB
91 lines
1.5 KiB
; SRs to find memory size and leave it as a "note" for the kernel
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; mmap_probe: ; literally just test the memory boundaries
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; push eax
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; push ebx
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; push edx
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; push ebp
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;
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; mov ebp, esi
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; add esi, 0x00000ff
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; and esi, ~0x00000ff
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; mmap_probe_addr:
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;
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; mmap_probe_done:
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e820_stats_addr equ 0x9820
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e820:
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pusha
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mov di, e820_stats_addr + 4
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mov ebx, 0 ; Must be 0
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mov bp, 0 ; entry count
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mov eax, 0xe820 ; function reg
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mov edx, "SMAP" ; function sig
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mov [es:di + 20], dword 1 ; fill
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mov ecx, 24 ; ask for 24 bytes
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int 0x15 ; Do the interupt
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jc e820_fail_unsup ; carry flag = (un)supported function
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cmp eax, edx ; eax should be = 'SMAP'
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jne e820_fail_smap ; if not then fail
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test ebx, ebx ; no entries
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je e820_fail_noent
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e820_lp:
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mov eax, 0xe820
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mov [es:di + 20], dword 1
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mov ecx, 24
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int 0x15
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jc e820_finish ; carry => finished -> save entry count
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e820_iter:
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; skip 0 entries
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jcxz e820_skip
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; check resp
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cmp cl, 20
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jbe e820_ntxt
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; check the ignore bit
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test byte [es:di + 20], 1
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je e820_skip
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e820_ntxt:
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mov ecx, [es:di + 8] ; lower mem length
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; test for 0
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or ecx, [es:di + 12]
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jz e820_skip
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; next entry
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inc bp
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add di, 24
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e820_skip:
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test ebx, ebx ; of ebx = 0 then complete
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jne e820_lp
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e820_finish:
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mov [e820_stats_addr], bp ; save entry count at e820_ent
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clc
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popa
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ret
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e820_fail_unsup:
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mov [e820_stats_addr], byte -1
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jmp e820_fail
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e820_fail_smap:
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mov [e820_stats_addr], byte -2
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jmp e820_fail
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e820_fail_noent:
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mov [e820_stats_addr], byte -3
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jmp e820_fail
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e820_fail:
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stc
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popa
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ret
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