[syslinux] simple message under BIOS/CSM/LEGACY

[Pascal]

hi,

I'm coming back to you on this subject (eg. display a short message
inviting the user to switch the PC to EFI/UEFI) after some field feedback.

here is the code now used :

; nasm nobioscsm.asm -f bin -o nobioscsm
bits 16
org 0x7C00
start:
    sti
    cld
    mov si, msg
    mov ah, 0x0E
    .loop lodsb
    or al, al
    jz halt
    int 0x10
    jmp .loop
halt:
    hlt
    jmp halt
msg:
    db 0x0D, 0x0A, 'Boot with BIOS/CSM/LEGACY no longer supported : reboot
with EFI/UEFI', 0

and here is what appears on the screen (Lenovo Thinkcenter M720) instead of
the expected message :

[image: clover.jpg]

the problem occurs mainly with the Lenovo brand (Thinkcentre M70
<https://www.google.com/search?q=Lenovo+Thinkcenter+M70>, Thinkcentre M720
<https://www.google.com/search?q=Lenovo+Thinkcenter+M720>), but not only
according to my information.

changing the partitioning to BIOS/Intel/MBR (instead of GPT) does not
change the problem : this last point makes me strongly believe that the
problem comes from the code...

regards, lacsaP.

Le mer. 12 oct. 2022 à 11:22, Frederic Pasteleurs <lists at askarel.be> a
écrit :

> 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
> > _______________________________________________
> > Syslinux mailing list
> > Submissions to Syslinux at syslinux.org
> > Unsubscribe or set options at:
> > https://lists.syslinux.org/syslinux
>
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