[syslinux] simple message under BIOS/CSM/LEGACY

[Frederic Pasteleurs]

Hello,

Here is how i would customize your code:

; nasm nobioscsm.asm -f bin -o nobioscsm

bits 16
org 0x7C00

start:
     sti ; no need to clear interrupts here: since we're going to crash anyway, leave them on
     cld ; Make sure we go forward
     mov si, msg
     mov ah, 0x0E
     .loop lodsb
     or al, al
     jz halt
     int 0x10
     jmp .loop

halt:
     hlt
     jmp halt ; The  hlt instruction sometimes behaves like a NOP. Just run in an infinite loop. CTRL-ALT-DEL should still continue to work to restart the machine

msg:
     db 0x0D, 0x0A, '** Boot with BIOS/CSM no longer supported : reboot with
EFI/UEFI **', 0

;times 510 - ($-$$) db 0
;dw 0xAA55


On 1/08/22 09:51, Pascal via Syslinux wrote:
> hi,
>
> I have a live system with only UEFI boot supported.
>
> to indicate this to users who have not yet switched to UEFI, I have below
> this simple little piece of code (partly found on the internet) that I
> compile with nasm and I push onto the MBR.
>
> it runs perfectly on some PCs and in virtual machine with Qemu, but refuses
> to run on other PCs by displaying either a kind of smiley logo or a simple
> blinking cursor.
>
> does anyone have any idea or clue about this?
>
> regards, lacsaP.
>
> 8<--------------------------------
> ; nasm nobioscsm.asm -f bin -o nobioscsm
>
> bits 16
> org 0x7C00
>
> start:
>      cli
>      mov si, msg
>      mov ah, 0x0E
>      .loop lodsb
>      or al, al
>      jz halt
>      int 0x10
>      jmp .loop
>
> halt:
>      hlt
>
> msg:
>      db 0x0D, 0x0A, '** Boot with BIOS/CSM no longer supported : reboot with
> EFI/UEFI **', 0
>
> ;times 510 - ($-$$) db 0
> ;dw 0xAA55
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