[syslinux] simple message under BIOS/CSM/LEGACY

[Pascal]

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