From mboxrd@z Thu Jan  1 00:00:00 1970
From: Miguel Bolanos <mike@linuxlabs.com>
Subject: Re: Experimental fix for my memcpy_{to,from}fs problem
Date: Tue, 01 Jun 2004 20:57:06 -0600
Sender: linux-8086-owner@vger.kernel.org
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To: Eduardo Pereira Habkost <ehabkost@conectiva.com.br>
Cc: linux-8086@vger.kernel.org

Greetings,

On Tue, 2004-06-01 at 16:30, Eduardo Pereira Habkost wrote:
> Interesting:
> 
> The diff between dev86-0.16.0 and 0.16.15 shows:
> 
> @@ -664,8 +693,34 @@
>         if( main_flag > 2 )
>            globl("environ");
>      }
> +#ifdef I8088
> +    regfuse = 0;
> +#endif
>      lbrace();
>      compound();
> +#ifdef I8088
> +    if (regfuse & callee1mask) {
> +        outstr("! Register");
> +        if (regfuse & INDREG0 & callee1mask) outstr(" BX");
> +        if (regfuse & INDREG1 & callee1mask) outstr(" SI");
> +       if (regfuse & INDREG2 & callee1mask) outstr(" DI");
> +       outstr(" used in function ");
> +       outnstr(funcname);
> +       if (optimise && !callersaves) {
> +           outstr(funcname);
> +           outnstr(".off = 0");
> +       }
> +    } else
> +       if (optimise && !callersaves) {
> +           outstr(funcname);
> +           outstr(".off = ");
> +#ifndef I80386
> +           outnhex(4);
> +#else
> +           outnhex(i386_32?12:4);
> +#endif
> +       }
> +#endif
>      clearfunclabels();
>  }
> 
> This register-saving optmization was added after 0.16.0. The fix is valid,
> but probably it will break systems using dev86 <= 0.16.0.
> 

Yes the fix is ok.. but it will break dev86 <= 0.16.0 versions... this
fact makes me hesitate a bit because Bruce does warn that 0.16.15 can
behave a bit unstable.
But we will see.

best wishes

Mike

> On Tue, Jun 01, 2004 at 07:02:35PM -0300, Eduardo Pereira Habkost wrote:
> > 
> > The following patch fixes the problem on my system. Probably
> > with some versions of bcc the patch will break something.
> > 
> > I've added code to save the contents of SI and DI, I don't know if the
> > callers of these functions assume that SI and DI are touched, but just
> > in case.
> > 
> > Now the system booted and ran flawlessly.
> > 
> > --- elks/arch/i86/mm/user.c	3 Jun 2002 22:22:58 -0000	1.15
> > +++ elks/arch/i86/mm/user.c	1 Jun 2004 20:44:51 -0000
> > @@ -34,10 +34,12 @@
> >  
> >  #ifndef S_SPLINT_S
> >  #asm
> > +	push	si
> > +	push	di
> >  	mov	dx,es
> >  	mov	bx,ds
> >  	mov	es,bx
> > -	mov	ax,[bp-6]	! source segment (local variable)
> > +	mov	ax,[bp-2]	! source segment (local variable)
> >  	mov	ds,ax
> >  	mov	di,[bp+4]	! destination address
> >  	mov	si,[bp+6]	! source address
> > @@ -47,8 +49,11 @@
> >  	movsb
> >  	mov	ds,bx
> >  	mov	es,dx
> > +	pop	di
> > +	pop	si
> >  #endasm
> >  #endif
> > +
> >  }
> >  
> >  int verified_memcpy_fromfs(void *daddr, void *saddr, size_t len)
> > @@ -69,8 +74,10 @@
> >  
> >  #ifndef S_SPLINT_S
> >  #asm
> > +	push	si
> > +	push	di
> >  	mov	dx,es
> > -	mov	ax,[bp-6]	! source segment (local variable)
> > +	mov	ax,[bp-2]	! source segment (local variable)
> >  	mov	es,ax
> >  	mov	di,[bp+4]	! destination address
> >  	mov	si,[bp+6]	! source address
> > @@ -79,6 +86,8 @@
> >  	rep
> >  	movsb
> >  	mov	es,dx
> > +	pop	di
> > +	pop	si
> >  #endasm
> >  #endif
> >  }
> > 
> > -- 
> > Eduardo
> 
>