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Index > OS Construction > VBE (vesa 3)

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Japheth



Joined: 26 Oct 2004
Posts: 151
Japheth
Stabia wrote:

Code:
        mov     edi, ADR_VAR_BIOS
        xor     eax, eax
        mov     ecx, 0x600/4
        rep     stosd                   ; mettre à 0 la zone des variables du BIOS

        mov     esp, eax
        add     eax, 100
        mov     ax, 0x28                ; la pile 16 bits de VBE
        mov     ss, ax
        movsx   eax, word [ADR_VAR_SYS+VBE_adrInit]
        call    pword [eax]
    


the "call pword [eax] dont work an PC reboot.


A brief look at your code tells that you're setting ESP to 0.

That's not forbidden in protected mode, but strange and possibly an error.
Post 18 Jan 2008, 16:43
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Stabia



Joined: 15 Jan 2008
Posts: 9
Location: Toulouse (France)
Stabia
in the image file extract of page 24 VBE official documentation ! (copying not allowed)

I add 100 because I think is strange !


Description:
Filesize: 16.4 KB
Viewed: 940 Time(s)

vbe.GIF


Post 18 Jan 2008, 18:27
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DOS386



Joined: 08 Dec 2006
Posts: 1901
DOS386
> in real mode this card dont share more than 64 k.

YES, but it's a very known issue of RM Laughing

> the "call pword [eax] dont work an PC reboot.

Code:
      xor     eax, eax
      mov     esp, eax
      call    blahblah ; CALL anything, this done in Ring0 WILL TripleFault Laughing
    


Your code is buggy Laughing

And you don't need all the stupid descriptors at all if you have an unpaged ZERO-based 4 GiB memory model Idea

Japheth wrote:

> That's not forbidden in protected mode, but strange and possibly an error.

It's perfectly legal and safe until you attempt to push anything Laughing

_________________
Bug Nr.: 12345

Title: Hello World program compiles to 100 KB !!!

Status: Closed: NOT a Bug
Post 20 Jan 2008, 02:06
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