如何检测启动加载器上的文本模式或图形模式？

Question

我想在运行bootloader的时候检测我现在只用BIOS intXX的模式。 如何检测现在是文本模式还是图形模式？ 我应该使用哪个中断函数？ 谢谢〜

---

我不明白，为什么当我运行INT 10，AL的值不会改变。

(0) Breakpoint 1, 0x00007c00 in ??() 
    Next at t=12943079 
    (0) [0x00007c00] 0000:7c00 (unk. ctxt): mov ah, 0x0f    ; b40f 
    <bochs:3> reg 
    eax: 0x0000aa55 43605 
    ecx: 0x00090000 589824 
    edx: 0x00000000 0 
    ebx: 0x00000000 0 
    esp: 0x0000ffd6 65494 
    ebp: 0x00000000 0 
    esi: 0x000e476c 935788 
    edi: 0x0000ffac 65452 
    eip: 0x00007c00 
    eflags 0x00000082: id vip vif ac vm rf nt IOPL=0 of df if tf SF zf af pf cf 
    <bochs:4> n 
    Next at t=12943080 
    (0) [0x00007c02] 0000:7c02 (unk. ctxt): mov al, 0xaa    ; b0aa 
    <bochs:5> reg 
    eax: 0x00000f55 3925 
    ecx: 0x00090000 589824 
    edx: 0x00000000 0 
    ebx: 0x00000000 0 
    esp: 0x0000ffd6 65494 
    ebp: 0x00000000 0 
    esi: 0x000e476c 935788 
    edi: 0x0000ffac 65452 
    eip: 0x00007c02 
    eflags 0x00000082: id vip vif ac vm rf nt IOPL=0 of df if tf SF zf af pf cf 
    <bochs:6> n 
    Next at t=12943081 
    (0) [0x00007c04] 0000:7c04 (unk. ctxt): int 0x0a     ; cd0a 
    <bochs:7> reg 
    eax: 0x00000faa 4010 
    ecx: 0x00090000 589824 
    edx: 0x00000000 0 
    ebx: 0x00000000 0 
    esp: 0x0000ffd6 65494 
    ebp: 0x00000000 0 
    esi: 0x000e476c 935788 
    edi: 0x0000ffac 65452 
    eip: 0x00007c04 
    eflags 0x00000082: id vip vif ac vm rf nt IOPL=0 of df if tf SF zf af pf cf 
    <bochs:8> n 
    Next at t=12943083 
    (0) [0x00007c06] 0000:7c06 (unk. ctxt): mov dl, al    ; 88c2 
    <bochs:9> reg 
    eax: 0x00000faa 4010 
    ecx: 0x00090000 589824 
    edx: 0x00000000 0 
    ebx: 0x00000000 0 
    esp: 0x0000ffd6 65494 
    ebp: 0x00000000 0 
    esi: 0x000e476c 935788 
    edi: 0x0000ffac 65452 
    eip: 0x00007c06 
    eflags 0x00000082: id vip vif ac vm rf nt IOPL=0 of df if tf SF zf af pf cf 
    <bochs:10> 

Answer 1

INT10, F 
AH = 0F 
on return: 
AL = mode currently set(page mode) 
BH = current display page 
Page mode: 
     AL = 00 40x25 B/W text (CGA,EGA,MCGA,VGA) 
     = 01 40x25 16 color text (CGA,EGA,MCGA,VGA) 
     = 02 80x25 16 shades of gray text (CGA,EGA,MCGA,VGA) 
     = 03 80x25 16 color text (CGA,EGA,MCGA,VGA) 
     = 04 320x200 4 color graphics (CGA,EGA,MCGA,VGA) 
     = 05 320x200 4 color graphics (CGA,EGA,MCGA,VGA) 
     = 06 640x200 B/W graphics (CGA,EGA,MCGA,VGA) 
     = 07 80x25 Monochrome text (MDA,HERC,EGA,VGA) 
     = 08 160x200 16 color graphics (PCjr) 
     = 09 320x200 16 color graphics (PCjr) 
     = 0A 640x200 4 color graphics (PCjr) 
     = 0B Reserved (EGA BIOS function 11) 
     = 0C Reserved (EGA BIOS function 11) 
     = 0D 320x200 16 color graphics (EGA,VGA) 
     = 0E 640x200 16 color graphics (EGA,VGA) 
     = 0F 640x350 Monochrome graphics (EGA,VGA) 
     = 10 640x350 16 color graphics (EGA or VGA with 128K) 
     640x350 4 color graphics (64K EGA) 
     = 11 640x480 B/W graphics (MCGA,VGA) 
     = 12 640x480 16 color graphics (VGA) 
     = 13 320x200 256 color graphics (MCGA,VGA) 
     = 8x EGA, MCGA or VGA ignore bit 7, see below 
     = 9x EGA, MCGA or VGA ignore bit 7, see below