Re: [Nasm-users] very strange behaviour indeed

[Frank K. <fbk...@ve...>]

Martin Knappe wrote:
> hi
> 
> i just came across some very strange behaviour of the nasm compiler
> take a look at this piece of code:
> 
> 
>    BITS 16
> 
>    ;some 16-Bit code
> 
>    cli
>  
>    lgdt [gdt_desc]
> 
>    mov eax, cr0   ;Enable
> 
>    or eax, 1   ;protected
> 
>    mov cr0, eax   ;mode
> 
>    jmp 20h:enter_32 ;where 20h is selector for this very segment
> 
> 
> 
> 
>    BITS 32
> 
> enter_32:
> 
>    hlt    
> 
> 
> if i execute this, the screen completely blanks upon the jump to enter_32
> 
> now if i leave out the line "BITS 32" (i.e. if i compile for 16 BITS), 
> the screen stays as it is!
> 
> is there a sensible explanation for this??

I see absolutely *no* difference between binaries with or without the 
"BITS 32". What strange behavior of the Nasm compiler are you referring to?

Unless you *do* see a difference in binaries, the strangeness originates 
elsewhere. What's your environment? Real boot? Dos? Emulator?

Best,
Frank