[ros-kernel] RE: RE: RE: Re: RE: Re: RE: Re: Old reactos

[Brian P. <br...@sg...>]

One more thing -- after this jump is made you have to make sure you're not
trying to run 16-bit code in a 32-bit code segment.

Brian

-----Original Message-----
From: Brian Palmer [mailto:br...@sg...]
Sent: Sunday, October 14, 2001 1:19 AM
To: ros...@re...
Subject: [ros-kernel] RE: RE: Re: RE: Re: RE: Re: Old reactos


You might try changing the jump instruction into a jump far instruction.
This would both clear the prefetch queue and set the CS register to it's
correct selector. You also might try removing jump instructions altogether
because if I remember correctly there are only a few instructions between
the time pmode is initialized and control is transferred to ReactOS. So
clearing the prefetch queue is really not neccesary. The more I think about
it however the more I dislike the idea of any jump instructions being there
at all because if you did do a far jump you would need to calculate the
32-bit offset from the selector's base which makes it overly complex (just
like this huge run-on sentence). Hope this helps.

Brian

-----Original Message-----
From: Jurgen Van Gael [mailto:jur...@st...]
Sent: Wednesday, October 10, 2001 1:08 PM
To: ros...@re...
Subject: [ros-kernel] RE: Re: RE: Re: RE: Re: Old reactos


Sorry, I tried this but the system still reboots. This is getting a very
anoying problem because I can't test the work I have done for reactos
(ole32). Has anybody got freeloader, and would that work loading reactos
on my system. The thing is I don't know enough assembler to solve the
problem on my own. Hoping for a quick solution.

Jurgen

-----Original Message-----
From: rene Tournois @free.fr [mailto:be...@fr...]
Sent: Wednesday, October 10, 2001 19:36
To: ros...@re...
Subject: [ros-kernel] Re: RE: Re: RE: Re: Old reactos



Try to insert a couple of NOP between the Label declaration and the jump
instruction. If i remember well, there a little bug in NASM about
this... (unsure, but no relationship with the prefetch anyway).

Betov.


>I am very sorry, I also had to change the .exit to exit because
>otherwise nasm wouldn't build loadros.
>
>And still the system reboots, but I can now put the loop after next:
>	mov	eax,cr0
>	or	eax,0x10001
>	mov	cr0,eax
>	jmp	next
>next:
>break:
>	jmp break
>	;;
>	;; NOTE: This must be position independant (no references to
>	;; non absolute variables)
>	;;
>
>	;;
>	;; Initalize segment registers
>	;;
>	mov	ax,KERNEL_DS
>	mov	ds,ax
>	mov	ss,ax
>	mov	es,ax
>	mov	fs,ax
>	mov	gs,ax
>
>
>If I put the break after mov gs, ax though, the system reboots.
>
>
>Jurgen
>
>-----Original Message-----
>From: Casper Hornstrup [mailto:ch...@us...]
>Sent: Wednesday, October 10, 2001 15:56
>To: ros...@re...
>Subject: [ros-kernel] Re: RE: Re: Old reactos
>
>
>On Wednesday 10 October 2001 00:40, Jurgen Van Gael wrote:
>> When I use the loop in loadros.asm, I get these results:
>>
>> If I put the break here:
>>
>> 		;;
>> 		;; Enter pmode and clear prefetch queue
>> 		;;
>> 		mov	eax,cr0
>> 		or	eax,0x10001
>> 		mov	cr0,eax
>> 	.break:
>> 		jmp .break
>> 		jmp	.next
>> 	.next:
>>
>> Then the system freezes with a blue screen
>>
>> When I put the loop after jmp .next, the system reboots.
>>
>> Am I right we are talking pmode right now. Could it be that the gdt
>> or
>
>> idt is not setup properly?
>
>Try changing:
>
>jmp	.next
>.next:
>
>
>to:
>
>jmp	next
>next:
>
>IIRC, it should be a far jump to clear the prefetch queue.
>
>- Casper
>
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